Ecosystem Services and Tropical Soils of India [1st ed. 2019] 978-3-030-22710-4, 978-3-030-22711-1

Table of contents :
Front Matter ....Pages i-xii
Soil Properties and Ecosystem Services: Overview and Introduction (D. K. Pal)....Pages 1-5
Agro-ecological Regions for Better Crop Planning and Ecosystem Services (D. K. Pal)....Pages 7-27
Organic Carbon Sequestration and Ecosystem Service of Indian Tropical Soils (D. K. Pal)....Pages 29-52
Is Soil Inorganic Carbon (CaCO3, SIC) Sequestration a Bane or a Hidden Treasure in Soil Ecosystem Services? (D. K. Pal)....Pages 53-64
Soil Modifiers (Ca-Zeolite and Gypsum) as Ecosystem Engineers in Soils of Humid and Semi-arid Tropical Climates (D. K. Pal)....Pages 65-84
Degradation in Indian Tropical Soils: A Commentary (D. K. Pal)....Pages 85-103
Summary and Concluding Remarks (D. K. Pal)....Pages 105-113

Citation preview

D. K. Pal

Ecosystem Services and Tropical Soils of India

Ecosystem Services and Tropical Soils of India

D. K. Pal

Ecosystem Services and Tropical Soils of India

D. K. Pal Division of Soil Resource Studies ICAR-NBSS&LUP Nagpur, Maharashtra, India

ISBN 978-3-030-22710-4    ISBN 978-3-030-22711-1 (eBook) https://doi.org/10.1007/978-3-030-22711-1 © Springer Nature Switzerland AG 2019 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Switzerland AG. The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

I dedicate this book to my parents and parents-in-law

Preface

Tropical soils have been traditionally considered as either agriculturally poor or virtually useless by many. To remove these misgivings, Indian soil scientists developed the state-of-the-art information in the last decade on tropical soils of India wherein they have presented scientific facts that would render soil as one of the important determinants of India’s economic status. Tropical soils are the most complex and important biomaterials but have an outstanding role in providing ecosystem services to mankind. Despite concerted efforts, this has not received adequate recognition. It is, hence, necessary to highlight the significance of soil and its effect on the global environment in an appropriate manner by including soil in the framework of ecosystem services and scientific policyand decision-making. This is the only way that soil science can be appreciated as a ‘progressive and innovative field of science’. Continuous research attempt in this direction is the need of the hour because earlier attempts to evaluate the ecosystem services did not give adequate attention to soil component and, when given, it is poorly defined. In studies made so far to link soil properties to ecosystem services, soil scientists often refrained from using ‘ecosystem service’ even though their research is devoted to linking soils to the ecosystem. Although much valuable work has been done on Indian tropical soils, it has been always difficult to manage these soils to sustain their productivity because some unique soil properties were hardly linked explicitly to soil ecosystem services. Therefore, soil care needs to be a constant research endeavour in Indian tropical environment as new soil knowledge base becomes critical when attempts are made to fill the gap between food production and future population growth. Realizing this urgency, research endeavours during the last few decades on benchmark and identified soil series by the Indian pedologists and earth scientists were made to provide insights into several aspects of five pedogenetically important soil orders like Alfisols, Mollisols, Ultisols, Vertisols and Inceptisols of tropical Indian environments. The global distribution of tropical soils and the recent advances in knowledge by researching on them in the Indian sub-­ continent now await a link between soil properties and ecosystem services for enhancing crop productivity and maintaining soil health in the twenty-first century. To establish the unique role of soil properties in ecosystem services of Indian vii

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t­ropical soils, some important lower level ecosystem services were chosen such as (1) agro-ecological regions as a tool for ecosystem services, (2) organic carbon sequestration and ecosystem service, (3) soil inorganic carbon sequestration in soil ecosystem services, (4) soil modifiers as ecosystem engineers and (5) degradation in Indian tropical soils. The author would like to acknowledge the valuable contributions of mentors and peers who have helped along the tenuous path of research. He will remain ever grateful to late Prof. S.K. Mukherjee and late Prof. B. B. Roy, who held the coveted position of Acharya P. C. Ray, Professor of Agricultural Chemistry at the University of Calcutta, for drawing him to soil research that offered more than a lifetime of fascinating problems to unravel. Soil property-driven ecosystem services of Indian tropical soils as presented in this book have been possible due to the significant research contributions made through a joint endeavour by the author along with his esteemed colleagues. They are Drs. T. Bhattacharyya, P. Chandran, S. K. Ray and Pramod Tiwari of ICAR-NBSS&LUP, Nagpur; Prof. Pankaj Srivastava of Geology Department, Delhi University; and also several M.Sc. and Ph.D. students at ICAR-­ NBSS&LUP.  Unstinted technical support and assistance received from Mrs. S.L.  Durge, G.K.  Kamble and L.M.  Kharbikar helped the author enormously in bringing the task to a successful fruition. The author duly acknowledges the sources of the diagrams and tables that have been adapted mostly from his publications. Furthermore, the author is grateful to his wife, Banani; his daughters, Deedhiti and Deepanwita; his brother-in-law, Dhrubajyoti; and his sons-in-law, Jai and Nachiket, for their patience, understanding, encouragement and above all unwavering moral support. Nagpur, Maharashtra, India  D. K. Pal 

Contents

1 Soil Properties and Ecosystem Services: Overview and Introduction����������������������������������������������������������������������������������������    1 References ��������������������������������������������������������������������������������������������������    4 2 Agro-ecological Regions for Better Crop Planning and Ecosystem Services ����������������������������������������������������������������������������    7 2.1 Introduction����������������������������������������������������������������������������������������    9 2.2 Refinement of Agro-ecological Zones Based on Soil Properties��������   10 2.3 Usefulness and Revision Needs of AESR������������������������������������������   12 2.3.1 Example 1 from SAT Non-zeolitic Vertisols��������������������������   12 2.3.2 Example 2 from SAT Zeolitic Vertisols����������������������������������   13 2.3.3 Example 3 from BSR and IGP Areas on Wheat Productivity������������������������������������������������������������   13 2.4 Generation of New Data for AESR Revision��������������������������������������   14 2.5 Computation of Length of Growing Period (LGP) Based on sHC��������������������������������������������������������������������������������������   16 2.5.1 Estimation of sHC������������������������������������������������������������������   16 2.6 Modification of AESR Boundaries ����������������������������������������������������   17 2.6.1 The Indo-Gangetic Plains ������������������������������������������������������   17 2.6.2 Black Soils Region������������������������������������������������������������������   20 2.7 Usefulness of Modified AESRs in BSR Observed in Better Compatibility Between Revised LGP and Cotton Yield: A Case Study����������������������������������������������������������   22 References ��������������������������������������������������������������������������������������������������   26 3 Organic Carbon Sequestration and Ecosystem Service of Indian Tropical Soils������������������������������������������������������������������������������   29 3.1 Introduction����������������������������������������������������������������������������������������   31 3.2 Other Factors of SOC Sequestration��������������������������������������������������   35 3.3 ‘4 per mille’ Concept and Enhancement of SOC Sequestration��������   45 3.4 Possible Ways to Enhance the SOC Sequestration ����������������������������   46 References ��������������������������������������������������������������������������������������������������   48

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4 Is Soil Inorganic Carbon (CaCO3, SIC) Sequestration a Bane or a Hidden Treasure in Soil Ecosystem Services? ��������������������������������   53 4.1 Introduction����������������������������������������������������������������������������������������   55 4.2 Formation of CaCO3 in SAT Soils: A Regressive Pedogenesis����������   57 4.3 SIC (CaCO3) as Soil Modifier: Its Soil Ecosystem Services��������������   60 4.4 SIC’s Ecosystem Services and Sustainability of SAT Soils���������������   61 References ��������������������������������������������������������������������������������������������������   63 5 Soil Modifiers (Ca-Zeolite and Gypsum) as Ecosystem Engineers in Soils of Humid and Semi-arid Tropical Climates ������������   65 5.1 Introduction����������������������������������������������������������������������������������������   66 5.2 Ca-Zeolites as Prolonged Ecosystem Engineer in Inceptisols, Alfisols and Mollisols of the Humid Tropical WG and KR Areas������������������������������������������������������������������������������   67 5.3 Ca-Zeolites as Transitory Ecosystem Engineer in Soils of SAT Marathwada Region of Central Peninsular India��������������������������������   74 5.4 Gypsum: A Better Ecosystem Engineer than Ca-Zeolites in Vertisols of SAT Environment��������������������������������������������������������   77 5.5 Zeolites Sustain Rice Cultivation in SAT Vertisols����������������������������   78 5.6 Ca-Zeolites in Adsorption and Desorption of Major Nutrients in SAT Vertisols������������������������������������������������������������������   79 5.6.1 Organic Carbon����������������������������������������������������������������������   79 5.6.2 Nitrogen����������������������������������������������������������������������������������   80 5.6.3 Phosphorus������������������������������������������������������������������������������   81 5.6.4 Potassium��������������������������������������������������������������������������������   81 References ��������������������������������������������������������������������������������������������������   82 6 Degradation in Indian Tropical Soils: A Commentary��������������������������   85 6.1 Introduction����������������������������������������������������������������������������������������   87 6.2 Physical Degradation Due to Water Erosion in Indian HT and SAT Soils��������������������������������������������������������������������������������������   89 6.2.1 HT Soils����������������������������������������������������������������������������������   89 6.2.2 SAT Soils��������������������������������������������������������������������������������   91 6.3 Chemical Degradation in Indian HT and SAT Soils ��������������������������   93 6.3.1 HT Soils����������������������������������������������������������������������������������   93 6.3.2 SAT Soils��������������������������������������������������������������������������������   95 References ��������������������������������������������������������������������������������������������������  100 7 Summary and Concluding Remarks��������������������������������������������������������  105 7.1 Agro-ecological Regions as a Tool for Ecosystem Services��������������  106 7.2 Organic Carbon Sequestration and Ecosystem Service����������������������  107 7.3 Soil Inorganic Carbon Sequestration in Soil Ecosystem Services������  109 7.4 Soil Modifiers as Ecosystem Engineers����������������������������������������������  111 7.5 Degradation in Indian Tropical Soils��������������������������������������������������  112

About the Author

D. K. Pal obtained his M.Sc. (Ag) degree in Agricultural Chemistry with specialization in Soil Science in 1970 and was awarded his Ph.D. degree in Agricultural Chemistry in 1976 from the University of Calcutta. He continued his training as a DAAD Postdoctoral Fellow at the Institute of Soil Science, University of Hannover, West Germany, in 1980–1981. He has had an illustrious research career spanning more than three and a half decades. The focus of this work has been the alluvial (Indo-Gangetic Alluvial Plains, IGP), red ferruginous and shrink-swell soils of the tropical environments of India. His research has expanded the basic knowledge in pedology, paleopedology, soil taxonomy, soil mineralogy, soil micromorphology and edaphology. He also pioneered new ideas on the development and management of the Indian tropical soils as evidenced by significant publications in several peer-reviewed leading international journals in soil, clay and earth sciences. Throughout his career, he has trained budding scientists in mineralogy, micromorphology, pedology and paleopedology. Under his stewardship, his team members have carved out a niche for themselves in soil research at national and international levels. He has mentored several M.Sc. and Ph.D. students of land resource management (LRM) of the Indian Council of Agricultural Research, National Bureau of Soil Survey and Land Use Planning (ICAR-NBSS&LUP), under the academic programme at Dr. Panjabrao Deshmukh Krishi Vidyapeeth (Dr. PDKV), Akola. He has been an Invited Speaker at multiple national and international conferences. He also continues to serve as a Reviewer for many journals of national and international repute and has contributed reviews and book chapters for national and international publishers. Recently, he has authored two books published by Springer International Publishing AG, Cham, Switzerland: (1) A Treatise of Indian and Tropical Soils published in 2017 and (2) Simple Methods to Study Pedology and Edaphology of Indian Tropical Soils published in 2019. In addition, he has been Coeditor of several books, proceedings and journals. He is the Life Member of many professional national societies in soil and earth science. He has been an Awardee of several prestigious awards (the Platinum Jubilee Commemoration xi

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Award of the Indian Society of Soil Science, New Delhi, for the year 2012; ICAR Award for Outstanding Interdisciplinary Team Research in Agriculture and Allied Sciences, Biennium, 2005–2006; and the 12th International Congress Commemoration Award, Indian Society of Soil Science, 1997) and fellowships (Honorary Member, the Clay Minerals Society of India, New Delhi, 2016; West Bengal Academy of Science and Technology, 2014; National Academy of Agricultural Sciences, New Delhi, 2010; Indian Society of Soil Science, New Delhi, 2001; and Maharashtra Academy of Sciences, Pune, 1996). He served as the Principal Scientist and Head, Division of Soil Resource Studies, ICAR-NBSS&LUP, Nagpur, and as a Visiting Scientist at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Telangana.

Chapter 1

Soil Properties and Ecosystem Services: Overview and Introduction

Abstract  Soils being the most complex and important biomaterials have a rightful place in the pedosphere, wherein lithosphere, atmosphere, hydrosphere and biosphere interact in an intimate manner. Although soils have a tremendous role in providing ecosystem services to mankind, adequate recognition of this fact is seldom highlighted in an appropriate manner. This has been the main reason why soil science still appears be an inward-looking field of science. To remove this misunderstanding, soil scientists need to argue in a manner that is readily understood by all and with both scientific and economic rigours so that they become able to establish the fact that soils are one of the important determinants of a nation’s economic status and, thus, inclusion of soils in the ecosystem services framework, policy and decision-making is indispensable. It is noticed that most studies attempted so far on the valuation of ecosystem services overlooked the need of a soil component, and in some studies such evaluation remained too generalized or poorly defined. In addition, in studies that were conducted to link soil properties to ecosystem services, soil scientists refrained from being bold to use ‘ecosystem service’ even though their research was devoted to linking soils to the ecosystem. Millennium Ecosystem Assessment, Economics and Ecosystems and Biodiversity and the Common International Classification Services have categorized ecosystem services, which are defined and classified differently, and they are often context specific. Ecosystem services are divided into lower-level services such as food, fibre, water supply and aesthetic values. It has been always difficult to manage Indian tropical soils to sustain their productivity because some unique soil properties are yet to be linked explicitly to soil ecosystem services even when Indian pedologists and earth scientists have provided insights into several aspects of pedogenetically important soil orders, for enhancing crop productivity and maintaining soil health in the twenty-first century. To establish the crucial role of soil properties in ecosystem services of Indian tropical soils, some pertinent lower-level ecosystem services are chosen such as (1) agro-ecological regions as a tool for ecosystem services, (2) organic carbon sequestration and ecosystem service, (3) soil inorganic carbon sequestration and soil ecosystem services, (4) soil modifiers as ecosystem engineers and (5) degradation in Indian tropical soils.

© Springer Nature Switzerland AG 2019 D. K. Pal, Ecosystem Services and Tropical Soils of India, https://doi.org/10.1007/978-3-030-22711-1_1

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1  Soil Properties and Ecosystem Services: Overview and Introduction

Keywords  Indian tropical soils · Ecosystem services · Agro-ecological zones · Soil organic and inorganic carbon · Soil modifiers · Soil degradation Soil is one of the most complex biomaterials on earth and might be described as border-like phenomenon of the earth’s surface. Soils belong to the pedosphere, wherein lithosphere, atmosphere, hydrosphere and biosphere interact with each other. While describing ecosystem for the services such as provisioning, supporting, regulating and cultural services, little emphasis on soil was given by most studies although soils are important component of the ecosystem (Adhikari and Hartemink 2016). Despite our expansive knowledge about soils regarding their formation and spatial distribution in different agro-ecological regions, a comprehensive insight on their functions that could be related to the ecosystem services is still inadequate. As a result, soil science represents a somewhat inward-looking field of science (Hartemink and McBratney 2008; Bouma 2014). In addition, the advice offered by soil scientists is couched in terms more easily understood by other colleagues than by politicians and economists who control the disposition of land. Therefore, it is essential that its arguments are presented in terms readily understood by all and with both scientific and economic rigour so that they are not easily refuted (Greenland 1991). This is probably an effective way to convince the fact that soils are one of the important determinants of a nation’s economic status. Thus, inclusion of soils in ecosystem services frameworks and policy is essential (Daily et al. 1997). In order to highlight soil as a natural capital or stock yielding a sustainable flow of useful goods and services, Dominati et al. (2010) suggested a framework to quantify soil natural capital in which soil properties, soil processes, and drivers were linked. However, most studies on the valuation of ecosystem services did not include soil as an important component, and when it was taken, it was poorly defined or remained as a generalized view (Liu et al. 2010; Winkler 2006). In view of recent scientific documentation, it appears that only a few studies made attempts to link soil properties to ecosystem services, but this may not be a reality because soil scientists might have hesitated to use ‘ecosystem service’ even though their research is devoted to linking soils to ecosystem services (Adhikari and Hartemink 2016). The majority of the studies attempted to relate soils to the defined soil functions that ultimately determined the delivery of ecosystem services. The organic link that exists between soil carbon, soil biota, soil nutrient cycling and moisture retention to ecosystem services is well highlighted by many researchers. In addition, the spatial aspects and dynamics of soil properties to ecosystem services are also studied through mapping or scenario modeling of future changes, not by using soil information directly but using environmental variables such as the land use and land cover (LULC) data as a proxy to soil (see the review by Adhikari and Hartemink 2016). It is observed that whenever soil variables are included in assessing ecosystem services and mapping, reliability of the model as well as mapping ended with more precision (Guo et al. 2001; Schägner et al. 2013). Since soil use and management soil properties are often modified, the soil ecosystem services depend on such modifications. Landslides, erosion, decline in soil

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carbon and biodiversity lead to soil degradation, which is often conceived to be of anthropogenic origin, poses a serious global challenge for food security and ecosystem sustainability (Godfray et  al. 2010; Montgomery 2010; Oldeman 1998). In addition to the contribution of soil to support food production for human welfare, it has multitude functions, which await appreciation (McBratney et al. 2014). They can be addressed by incorporating soils to ecosystem services framework and linking it to the multitude of functions it provides (Daily et al. 1997; Dominati et al. 2010, 2014). Ecosystem services are categorized by the Millennium Ecosystem Assessment (MEA 2005), the Economics and Ecosystems and Biodiversity (TEEB 2010) and the Common International Classification Services (CICES 2011). However, ecosystem services are defined and classified differently, and they are often context specific (Fisher et  al. 2009). In all three systems, four major groups of services are distinguished: provisional, regulating, cultural and supporting services. They were divided into lower-level services such as food, fibre, water supply and aesthetic values (Adhikari and Hartemink 2016). But it would be interesting to follow how the lower-level services (e.g., food production, moisture retention and gas emissions) are linked to the tropical soils of the Indian sub-continent. The major part of the land area in India is in the region lying between the Tropic of Cancer and Tropic of Capricorn, and the soils therein are termed ‘tropical soils’. Many, however, think of tropical soils as the soils of the hot and humid tropics only. Such soils are generally conceived to be deep red and highly weathered soils that are often thought improperly to be either agriculturally poor or virtually useless (Sanchez 1976; Eswaran et al. 1992). On the contrary, India has five distinct bioclimatic systems (Bhattacharjee et al. 1982) with varying mean annual rainfall (MAR), and the major soils of India are Vertisols, Mollisols, Alfisols, Ultisols, Aridisols, Inceptisols and Entisols covering 8.1%, 0.5%, 12.8%, 2.6%, 4.1%, 39.4% and 23.9%, respectively, of the total geographical area (TGA) of the country (Bhattacharyya et al. 2009). These soils are not confined to a single production system and contribute substantially to India’s growing self-sufficiency in food production and food stocks (Pal et al. 2015; Bhattacharyya et al. 2014). This has been made possible because of favourable natural endowment of soils that remained highly responsive to management interventions made mainly by farming communities with the support from national and international institutions. Since India is primarily an agrarian society, soil care through recommended practices has been the engine of economic development, thereby eliminating large portion of poverty and considerable transformation of rural communities (Pal et al. 2012, 2014, 2015; Srivastava et  al. 2015). This suggests that although much valuable research under National Agricultural Research Systems (NARS) is done on the Indian tropical soil, their soil properties are yet to be linked to ecosystem services in view of continuous use and management practices. As soil plays a crucial role in ecosystem functioning, such linking needs to be a constant research agenda in national development in the Indian context. This is imperative since soil ecosystem services become critical amidst the modifications of soil properties due to land uses, Holocene climate change, ­endowment of soil modifiers and degradation processes. In addition, this will espe-

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cially facilitate in bridging the gap between food production and future population growth. More than one-third of the soils of the world are tropical soils. Global distribution of these soils and the recent advances in knowledge on Entisols, Inceptisols, Mollisols, Alfisols, Vertisols and Ultisols in the Indian sub-continent (Pal 2017, 2019) now await a link between soil properties and ecosystem services in this part of the tropical world for enhancing crop productivity and maintaining soil health in the twenty-first century. In the present book, some pertinent lower-level ecosystem services are chosen such as (1) agro-ecological regions for better crop planning and ecosystem services, (2) organic carbon sequestration and ecosystem service of Indian tropical soils, (3) soil inorganic carbon (CaCO3, SIC) sequestration and soil ecosystem services (4) soil modifiers (Ca-zeolite and gypsum) as ecosystem engineers in humid and semi-arid tropical soils and (5) degradation in Indian tropical soils.

References Adhikari K, Hartemink AE (2016) Linking soils to ecosystem services-a global review. Geoderma 262:101–111 Bhattacharjee JC, Roychaudhury C, Landey RJ, Pandey S (1982) Bioclimatic analysis of India. NBSSLUP Bull 7. National bureau of soil survey and land use planning (ICAR), Nagpur, India, p 21+map Bhattacharyya T, Sarkar D, Sehgal J, Velayutham M, Gajbhiye KS, Nagar AP, Nimkhedkar SS (2009) Soil taxonomic database of India and the states (1:250,000 scale). NBSS&LUP Publication 143, 266 pp Bhattacharyya T, Chandran P, Ray SK, Mandal C, Tiwary P, Pal DK, Wani SP, Sahrawat KL (2014) Processes determining the sequestration and maintenance of carbon in soils: a synthesis of research from tropical India. Soil Horiz:1–16. https://doi.org/10.2136/sh14-01-0001 Bouma J (2014) Soil science contributions towards sustainable development goals and their implementation: linking soil functions with ecosystem services. J Plant Nutr Soil Sci 177:111–120 CICES (2011) Common international classification of ecosystem services (CICES). Update European Environment Agency, Nottingham Daily GC, Matson PA, Vitousek PM (1997) Ecosystem services supplied by soil. In: Daily GC (ed) Nature services: societal dependence on natural ecosystems. Island Press, Washington DC, pp 113–132 Dominati E, Patterson M, Mackay A (2010) A framework for classifying and quantifying the natural capital and ecosystem services of soils. Ecol Econ 69:1858–1868 Dominati E, Mackay A, Green S, Patterson M (2014) A soil change-based methodology for the quantification and valuation of ecosystem services from agro-ecosystems: a case study of pastoral agriculture in New Zealand. Ecol Econ 100:119–129 Eswaran H, Kimble J, Cook T, Beinroth FH (1992) Soil diversity in the tropics: implications for agricultural development. In: Lal R, Sanchez PA (eds) Myths and science of soils of the tropics, SSSA special publication number 29. SSSA, Inc and ACA, Madison, pp 1–16 Fisher B, Turner RK, Morling P (2009) Defining and classifying ecosystem services for decision making. Ecol Econ 68:643–653 Godfray HCJ, Beddington JR, Crute IR, Haddad L, Lawrence D, Muir JF, Pretty J, Robinson S, Thomas SM, Toulmin C (2010) Food security: the challenge of feeding 9 billion people. Science 327:812–818

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Greenland DJ (1991) The contributions of soil science to society-past, present, and future. Soil Sci 151:19–23 Guo Z, Xiao X, Gan Y, Zheng Y (2001) Ecosystem functions, services and their values-a case study in Xingshan County of China. Ecol Econ 38:141–154 Hartemink AE, McBratney A (2008) A soil science renaissance. Geoderma 148:123–129 Liu S, Costanza R, Farber S, Troy A (2010) Valuing ecosystem services. Theory, practice, and the need for a transdisciplinary synthesis. In: Limburg K, Costanza R (eds) Ecological economics reviews. Annals of the New York Academic Sciences, pp 54–78 McBratney AB, Field DJ, Koch A (2014) The dimensions of soil security. Geoderma 213:203–213 MEA (2005) Millennium ecosystem assessment: ecosystems and human well-being 5. Island Press, Washington, DC Montgomery HL (2010) How is soil made. Crabtree Publishing, New York Oldeman LR (1998) Soil degradation: a threat to food security. International Soil Reference and Information Center, Wageningen Pal DK (2017) A treatise of Indian and tropical soils. Springer, Cham Pal DK (2019) Simple methods to study pedology and edaphology of Indian tropical soils. Springer, Cham Pal DK, Wani SP, Sahrawat KL (2012) Vertisols of tropical Indian environments: pedology and edaphology. Geoderma 189–190:28–49 Pal DK, Wani SP, Sahrawat KL, Srivastava P (2014) Red ferruginous soils of tropical Indian environments: a review of the pedogenic processes and its implications for edaphology. Catena 121:260–278. https://doi.org/10.1016/j.catena2014.05.023 Pal DK, Wani SP, Sahrawat KL (2015) Carbon sequestration in Indian soils: present status and the potential. Proc Natl Acad Sci Biol Sci (NASB), India 85:337–358. https://doi.org/10.1007/ s40011-014-0351-6 Sanchez PA (1976) Properties and management of soils in the tropics. Wiley, New York Schägner JP, Brander L, Maes J, Hartje V (2013) Mapping ecosystem services' values: current practice and future prospects. Ecosyst Serv 4:33–46 Srivastava P, Pal DK, Aruche KM, Wani SP, Sahrawat KL (2015) Soils of the indo-Gangetic Plains: a pedogenic response to landscape stability, climatic variability and anthropogenic activity during the Holocene. Earth-Sci Rev 140:54–71. https://doi.org/10.1016/j.earscirev.2014.10.010 TEEB (2010) The economics of ecosystems and biodiversity: ecological and economic foundations. UNEP/Earthprint Winkler R (2006) Valuation of ecosystem goods and services part 1: an integrated dynamic approach. Ecol Econ 59:82–93

Chapter 2

Agro-ecological Regions for Better Crop Planning and Ecosystem Services

Abstract  Food and nutritional security on sustainable basis will remain the major challenge for Indian agriculture like in many tropical countries of the world in the twenty-first century. Through irrigation, an increased crop production may be possible, but the speed of the expansion of irrigation potential in 140 m ha of Indian arable land is not taking place at the expected speed at present. On the other hand, an improvement of the water productivity of rainfed situation holds, particularly in the semi-arid tropical (SAT) region, a promise to increase the crop productivity due to a large gap between farmers’ yield and achievable yield. This gap can be filled considerably by adopting a sustainable management approach of natural resources, and in order to achieve this goal, an assessment of land/water and climate resources to create an integrated system needs to be given the highest priority. To make it happen, the task is to create near-homogeneous soil climatic regions that are compatible for sustenance of a particular group of crops and cultivars. A near-homogenous area having similar soil, bioclimate and moisture availability related to crop production is known as agro-ecological regions (AER). The AER made following the creation of broad crop feasibility zone based on length of moisture availability period, which was superimposed on FAO/UNESCO global soil and terrain map of 1:5000, 000 scales by Indian researchers as ecosystem service providers, is very broad and thus fraught with difficulty for crop planning both at state and district levels. Thereafter, several attempts were made in the recent past including the refinement of agro-­ ecological regions by the ICAR-NBSS &LUP to divide 20 agro-ecological regions (AER) into 60 agro-ecological subregions (AESRs) in 1999. The usefulness of 60 AESRs as ecosystem services was realized while estimating the stocks of soil carbon and available potassium of the Indo-Gangetic Plains (IGP) and black soil regions (BSR) and in prioritizing areas of carbon sequestration. But further research is warranted to refine the AESR boundaries in SAT climate, which can match rainfall with crop water requirement. Therefore, collection of antecedent soil moisture, after the cessation of rains when rainfall (P) falls short of 0.5 potential evapotranspiration (PE), becomes an essential requirement. In absence of such essential data, the present AESR boundaries vis-à-vis crop performance exhibit scenarios a little away from reality in SAT areas. The soil moisture dynamics is greatly influenced by saturated hydraulic conductivity (sHC), which in turn is affected by exchangeable sodium percentage (ESP). Besides, gypsum, Ca-rich zeolites and palygorskite also © Springer Nature Switzerland AG 2019 D. K. Pal, Ecosystem Services and Tropical Soils of India, https://doi.org/10.1007/978-3-030-22711-1_2

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influence soil moisture. In the FAO method, the length of growing period (LGP) is computed from monthly/decadal precipitation (P) and potential evapotranspiration (PET). Available water holding capacity (AWC) of shrink-swell soils was computed considering the available water of all the soil layers to a depth of 1 m or up to least permeable layer (sHC  210 days). At a later date, the importance of narrower LGP interval of 30 days for diverse crop suitability and the need of further subdivisions of bioclimate and some important soil quality parameters like soil depth and available water capacity (AWC) were realized. This led ICARNBSS&LUP (Velayutham et  al. 1999) to divide 20 AER into 60 agro-­ecological subregions (AESRs) (Fig. 2.1).

Fig. 2.1  Original AESR map of India, 1999. (Adapted from Velayutham et al. 1999)

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2  Agro-ecological Regions for Better Crop Planning and Ecosystem Services

2.3  Usefulness and Revision Needs of AESR Although the usefulness of 60 AESRs as ecosystem services has been demonstrated in estimating the stocks of soil carbon and available potassium of the Indo-Gangetic Plains (IGP) and black soil regions (BSR) and also in prioritizing areas for carbon sequestration (Bhattacharyya et al. 2007, 2008), further refinement of AESR boundaries in semi-arid tropical (SAT) climate to match rainfall with crop water requirement has been felt to be necessary for quite some time. To address this critical issue, there is a need to gather antecedent soil moisture after the cessation of rains when rainfall (P) falls short of 0.5 potential evapotranspiration (PE). In absence of such essential data, the present AESR boundaries vis-à-vis crop performance exhibit scenarios a little away from reality under SAT climatic environments (Pal et al. 2009a). This incompatibility is explicitly demonstrated through following few examples.

2.3.1  Example 1 from SAT Non-zeolitic Vertisols Nagpur, Amravati and Akola districts of Central India in the state of Maharashtra occur in subhumid dry to semi-arid moist bioclimatic zones and belong to contiguous AESRs 10.2 and 6.3. The water balance from these districts, based on a 30-year climatic data, indicates that the humid and length of growing periods of Nagpur (FAO 1976) are 103  days and 183  days, respectively. Both Amravati and Akola districts have shorter humid periods and length of growing periods than Nagpur. There is a difference of 6 days in humid periods between Amravati and Akola (Kadu et al. 2003), but their growing periods are comparable (152 versus 150 days). It was observed that occurring in the ustic soil moisture regime and hyperthermic temperature regime and under similar soil management by farmers in 32 deep cracking clay soils (Vertisols) areas, yields of cotton (seed plus lint) were better in soils of Nagpur (1000–1800 kg ha−1) than those of Amravati (600–1700 kg ha−1) and Akola (600– 1000 kg ha−1) (Kadu et al. 2003; Pal et al. 2009a, b; Deshmukh et al. 2014). Due to regressive pedogenesis (Pal et al. 2013), the subsoils in the western part of Amravati and Akola districts are becoming sodic due to accelerated rate of formation and accumulation of pedogenic CaCO3 (Pal et al. 2009b). This impairs hydraulic conductivity (sHC) of Vertisols and reduces crop yield as evidenced by a significant positive correlation between yield of cotton and sHC (Kadu et al. 2003) even when both the soils possess considerable amounts of available water capacity (AWC) (Kadu et al. 2003; Deshmukh et al. 2014). This clearly demonstrates that analytical protocols adopted for calculating LGP so far for soils of BSR of SAT climate need some revision to reach real soil water situation in the profile to make it a more worthwhile and robust crop-linked soil climate parameter.

2.3  Usefulness and Revision Needs of AESR

13

2.3.2  Example 2 from SAT Zeolitic Vertisols Cotton is cultivated in Vertisols in arid (dry) and semi-arid (dry) bioclimatic zones at Sokhda and Semla benchmark sites of Gujarat, which belong to AESRs 2.4 and 5.1, respectively. Despite climatic aridity-related soil degradation observed in concomitant development of pedogenic CaCO3 and sodicity (Pal et al. 2000, 2016), cotton yields are 1800 kg ha−1 to 2000 kg ha−1 in Sokhda and Semla Vertisols and resemble similar crop performance in wetter parts of the country, namely, AESRs 10.2 and 6.3. Also, the yields are comparable to those obtained in Vertisols of Nagpur district of Central India under subhumid dry bioclimatic zone (AESR 10.2). This is a paradoxical situation. The fact is the presence of Ca-zeolites in these Vertisols act as natural soil modifiers to ward off the adverse effects of Na+ ions and enhance the soil drainage. Improved soil water storage mediated through the improvement of drainage helps to produce crop yield similar to wetter climate (Pal et  al. 2006). This shows that different AESRs can capture similar performance of cotton in Vertisols provided adequate soil moisture during the crop growth is available. It is known how the management practices (irrigation, crop variety) can overshadow the boundaries of AESRs. But the present example shows how a natural modifier can help to cut across the boundaries of AESR if crop performance is considered as an important parameter. It is now understood that soil moisture stored after rains in sodic and nonzeolitic, sodic and zeolitic and non-sodic and non-­zeolitic shrink-swell soils under SAT environment does not remain in equal amounts for crop growth. Therefore, under such circumstances, methods to calculate the length of growing period (LGP) (FAO 1976; NBSS&LUP 1994) by assuming 100 mm as stored soil moisture are not appropriate and need a revision (Pal et al. 2009b).

2.3.3  E  xample 3 from BSR and IGP Areas on Wheat Productivity Wheat productivity (Fig. 2.2) in the IGP soils indicates that states like Punjab and Haryana (AESR 9.1) produces nearly 4500  kg  ha−1 of wheat under irrigation, whereas Bhojpur district of Bihar representing AESR 9.2 produces only 1600 kg ha−1 (DES 2015) mostly as rainfed crop. The soils (Haplustepts) of Punjab and Haryana do not experience waterlogging like Bhojpur soils of Bihar. In Rajasthan, some Vertisols (Jhalipura, Kota district) of semi-arid (dry) bioclimatic region are grown for wheat under very limited irrigation, and its yields (4500 kg ha−1) are comparable to those of Punjab and Haryana despite the fact that the texture of Vertisols are clayey and believed to have poor drainage conditions. However, Vertisols of Jhalipura area contain Ca-zeolites, which help in improving the sHC >10 mm hr−1 (Pal et  al. 2006). This unique situation warrants a re-examination of the AESR boundaries, and the computation of LGP definitely needs some modification based on the index soil properties that can help relating to antecedent soil moisture

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5000 4500

Productivity (kgha-1)

4000 3500 3000 2500 2000 1500 1000 500 0

State

Fig. 2.2  Wheat productivity in different states of India. (Adapted from DES 2015)

between the rains during the crop growth in these SAT areas (Pal et  al. 2009a). Under rainfed conditions, the yield of deep-rooted crops in cracking clay soils (Vertisols) depends primarily on the amount of rain entered and stored at depth in soil profile and the extent to which this soil water is released during the crop growth. Previous data obtained at ICAR-NBSS&LUP (Kadu et  al. 2003; Pal et  al. 2006, 2009b) indicates that both retention and release of soil water are governed by the nature and content of clay minerals and also by the nature of exchangeable cations. In arid and semi-arid environment, the subsoils become sodic due to accelerated rate of formation and accumulation of pedogenic CaCO3. This process impairs the sHC. Therefore, it has become imperative to revise the AESR boundaries incorporating revised LGP estimates based on soil properties like sHC.

2.4  Generation of New Data for AESR Revision Despite having excellent national repository of various soil maps at both large and small scales, geo-referenced information to their spatial domain for researchers engaged in natural resource management, crop and environment modeling has not been forthcoming (Bhattacharyya et al. 2014a). Thus, the flowing gaps have existed for long.

2.4  Generation of New Data for AESR Revision

15

• Benchmark database at national scale of biophysical factors was not linked with GIS. • Complete datasets on biophysical parameters are not available for the preparation of a soil information system under SOTER environment, compatible to the global soil database. • Quantitative land evaluation for suggesting alternate land use options was not attempted due to non-availability of comprehensive biophysical datasets, and land quality parameters influencing production system were not adequately addressed. In view of immediate concern about the use of soil map information for agricultural land use planning, ICAR assisted and World Bank funded a National Agricultural Innovative Project (NAIP) ‘Geo referenced Soil Information System for Land Use Planning and Monitoring Soil and Land Quality for Agriculture’ which was executed during 2009–2014 by ICAR-NBSS&LUP as the Consortium Leader (Bhattacharyya et al. 2014a, b; Bhattacharyya and Pal 2014). One of the three primary objectives of this NAIP was ‘To prepare modified AESR Map for agricultural land use planning’. The outcome from this project was hoped to serve as a soil information system for the natural resource managers of the country and would represent a robust platform that would facilitate future monitoring of the changes in soil properties. This assumes added importance to agricultural land use planning in view of the declining trends in factor productivity. In this NAIP, two major food production zones of the country, viz. the Indo-Gangetic Plains (IGP) and the black soil regions (BSR), were selected for the study. Since irrigation potential is limited and expansion of irrigated area is tardy, rainfed agriculture holds promise to satisfy future food needs. The spatio-temporal information on sHC and soil water retention-release behaviour are essential for rainfed agriculture in SAT areas (Bhattacharyya and Pal 2014). The sHC greatly influences the drainage process, soil water retention and release behaviour that affects the crop performance. However, the sHC and water retention are not measured in a routine soil survey but can be estimated from easily measurable soil parameters through pedotransfer functions (PTFs). In the NAIP, PTFs for sHC and water retention were developed separately for the soils of IGP and BSR (Tiwary et al. 2014). For the IGP soils, the sHC is affected by the increased subsoil bulk density due to intensive cultivation. In the BSR, the presence of Na+ and Mg++ ions affects the drainage and water retention and release behaviour of the soils. Therefore, these soil parameters were considered while developing the PTFs. The IGP with an area of 52.01  m  ha is represented by 417 soil pedons (data point), and the BSR, on the other hand, is represented by 425 pedons covering an area of 76.4  m  ha (for details please refer to Figs.  2 and 5, Bhattacharyya et  al. 2014a, and Figs. 1 and 2, Bhattacharyya et al. 2014b). Most of the pedons represent the benchmark (BM) soils of the IGP and BSR. The other pedons’ data were collected from district and watershed/village reports on 1:50,000 scale or larger ones surveyed by ICAR-NBSS&LUP from time to time (Bhattacharyya et al.2014a, b; Mandal et al. 2014).

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2.5  C  omputation of Length of Growing Period (LGP) Based on sHC In the FAO method, the LGP is computed from monthly/decadal precipitation (P) and potential evapotranspiration (PET) (FAO 1983). Reassessment of LGP values in the BSR is necessary due to various reasons which shall be explained here. It is already mentioned that the soil water retention-release behaviour is greatly influenced by the sHC and significant reduction in cotton yield was observed in the soils with sHC 581 267–389 250–300

Red loamy well-drained 300–400 soils Black soils (calcareous), 500 Deep well-drained calcareous clay soils with occasional flooding at places. Deep well-drained clayey soils Mixed red and black 250–400 soils

8.2 (120–150)

–

150–180

8.3 (120–150)

8.3a

180–210

8.3b

150–180

10.1 (150–180) –

180–210

10.2 (150–180) –

180–210

10.3 (150–180) 10.3a 10.3b

180–210 150–180

10.4 (180–210) –

180

Deep well-drained clayey soils with moderate to severe erosion, at places imperfectly drained calcareous soils Black soils of Cauvery Delta Red loamy soils

>200

>300 No cultivation of cotton No cultivation of cotton >200

No. of modifications made and justificationsb Old polygon boundary modified AESR is divided in to two Please see b

Old polygon boundary modified Please see b

AESR is divided in to two

Boundary modification based on soils Dominantly black soils Old polygon boundary modified Old polygon Black soils, well drained No cultivation of boundary Red loamy soils modified cotton 425 Please see b Deep to very deep, well-drained to moderately well-drained clay soils with moderate to slight erosion, at places calcareous and cracking clay soils Dominantly black soils, well drained

(continued)

2.7  Usefulness of Modified AESRs in BSR Observed in Better Compatibility…

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Table 2.1 (continued)

Modified Original AESR,1999 Modified (LGP, days) Soils (LGP, Days) AESR 11.0 (150–180) 11.1 210 + Black, red and yellow sandy loam 11.2 180–210 Black soils, at places imperfectly to poorly drained 12.1 (180–210) 12.1a 150–180 Dominantly black soils of Mahanadi basin, poorly to imperfectly drained 12.1b 210 + Mixed red loamy and black soils 12.1c 180–210 Red sandy loam soils 12.2 (180–210) – 180 + Deep, poorly to imperfectly drained loamy to clay soils with occasional to severe flooding. At places moderate deep, well-drained loamy soils 18.1 (90–120) – Deep, well-drained calcareous clayey to loamy soils, at places imperfectly drained calcareous soils 18.4 (180–210) – Deep, poorly to imperfectly drained clayey soils with moderate flooding and slight to strong salinity. At places, deep, well-drained soils 19.1 (180–210) 19.1a 180–210 Red loamy soils, well-drained, severe erosion and moderate salinity 19.1b 180–210 Calcareous, well-­ drained black soils, slight to moderate salinity

Average cotton yield (Lint, kg ha−1) (2007–2013) 200 >250

No. of modifications made and justificationsb AESR is divided in to two

AESR is No cultivation of divided in to three cotton

Please see b No cultivation of cotton

100–400

Please see b

>400

Please see b

AESR is No cultivation of divided in to two cotton >300

(continued)

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Table 2.1 (continued) Average cotton yield (Lint, kg Modified Original ha−1) AESR,1999 Modified (LGP, days) Soils (LGP, Days) AESR (2007–2013) 19.3 (240–270) – – Moderately deep to deep No cultivation of poorly drained cotton calcareous clay soils with slight to strong salinity. At places imperfectly drained clay soils with moderate flooding and salinity

No. of modifications made and justificationsb Please seeb

Adapted from Mandal et al. (2014), Bhattacharya et al. (2014a) These AESRs were not further sub-divided (Mandal et al. 2014) due to lack of relevant soil data. Boundaries of the polygons were revised keeping in view the administrative boundaries and at places physiography only

a

b

References Bhattacharyya T, Pal DK (2014) Special Section on ‘Geo referenced soil information system for land use planning and monitoring soil and land quality for agriculture. Curr Sci 107 Bhattacharyya T, Mandal C, Mandal DK, Prasad J, Tiwary P, Venugopalan MV, Pal DK (2015) Agro-eco sub-region based crop planning in the black soil regions and Indo-Gangetic Plains -Application of soil information system. Proc Indian Nat Sci Acad 81:1151–1170. https://doi. org/10.16943/ptinsa/2015/v81i5/48335 Bhattacharyya T, Pal DK, Chandran P, Ray SK, Durge SL, Mandal C, Telpande B (2007) Available K reserve of two major crop growing regions (alluvial and shrink–swell soils). Indian J Fertil 3:41–52 Bhattacharyya T, Pal DK, Chandran P, Ray SK, Mandal C, Telpande B (2008) Soil carbon storage capacity as a tool to prioritise areas for carbon sequestration. Curr Sci 95:482–494 Bhattacharyya T, Sarkar D, Ray SK, Chandran P, Pal DK et al. (2014a) Final project report: Geo referenced soil information system for land use planning and monitoring soil and land quality for agriculture (NAIP, C-4), NBSS Publication no. 1074, NBSS&LUP (ICAR), Nagpur, p 92 Bhattacharyya T, Sarkar D, Ray SK, Chandran P, Pal DK et al (2014b) Geo referenced soil information system: assessment of database. Curr Sci 107:1400–1419 DES (2015) Crop production statistics. Directorate of Economics and Statistics (DES), Department of Agriculture, Cooperation and Farmers Welfare, Ministry of Agriculture and Farmers Welfare, Government of India, New Delhi. https://aps.dac.gov.in/APY/Public_Report1.aspx Deshmukh HV, Chandran P, Pal DK, Ray SK, Bhattacharyya T, Potdar SS (2014) A pragmatic method to estimate plant available water capacity (PAWC) of rainfed cracking clay soils (Vertisols) of Maharashtra, Central India. Clay Res 33:1–14 FAO (1976) Frame work of land evaluation. Soils Bulletin 32. FAO, Rome, p 72 FAO (1978–1981) Report on agro-ecological zones project. World soil resources report, 48. FAO, Rome FAO (1983) Guidelines: land evaluation for rainfed agriculture. FAO Soils Bulletin 52. FAO, Rome 52:237 FAO (1995) Planning for sustainable use of land resources: towards a new approach. FAO Land and Water Bulletin no. 2, Land and Water Development Division, FAO, Rome FAO (2002) Global agro-ecological assessment for agriculture in the 21st century: methodologies and results, pp 1–5

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FAO/UNESCO (1974) Soil map of world, Vol. II (Asia). UNESCO, Paris Kadu PR, Vaidya PH, Balpande SS, Satyavathi PLA, Pal DK (2003) Use of hydraulic conductivity to evaluate the suitability of Vertisols for deep rooted crops in semi-arid parts of central India. Soil Use Manag 19:208–216 Khanna SS (1989) The Agro-climatic approach. In: Survey of Indian agriculture, The Hindu, Madras, India, pp 28–35 Krishnan A, Singh M (1968) Soil climatic zones in relation to cropping patterns. In: Proceedings of the symposium on cropping patterns, Indian Council of Agricultural Research, New Delhi, pp 172–185 Mandal C, Mandal DK, Bhattacharyya T, Sarkar D, Pal DK et al (2014) Revisiting agro-ecological sub-regions of India- a case study of two major food production zones. Curr Sci 107:1519–1536 Murthy RS, Pandey S (1978) Delineations of agro-ecological regions of India. Paper presented in Commission V, 11th Congress of ISSS, Edmonton, Canada, 19–27 June, 1978 NAAS (2009) Agriculture sector: status and performance in states of Indian agriculture. National Academy of Agricultural Sciences, New Delhi, pp 2–34 NBSS&LUP (1994) Proceedings of national meeting on soil-site suitability criteria for different crops. Feb. 7–8, Nagpur, India, p 20 Pal DK, Dasog GS, Vadivelu S, Ahuja RL, Bhattacharyya T (2000) Secondary calcium carbonate in soils of arid and semi-arid regions of India. In: Lal R, Kimble JM, Eswaran H, Stewart BA (eds) Global climate change and pedogenic carbonates. Lewis Publishers, Boca Raton, pp 149–185 Pal DK, Bhattacharyya T, Ray SK, Bhuse SR (2003) Developing a model on the formation and resilience of naturally degraded black soils of the peninsular India as a decision support system for better land use planning. NRDMS, Department of Science and Technology (Govt. of India) Project Report. NBSSLUP (ICAR), Nagpur, p 144 Pal DK, Bhattacharyya T, Ray SK, Chandran P, Srivastava P, Durge SL, Bhuse SR (2006) Significance of soil modifiers (Ca-zeolites and gypsum) in naturally degraded Vertisols of the peninsular India in redefining the sodic soils. Geoderma 136:210–228 Pal DK, Mandal DK, Bhattacharyya T, Mandal C, Sarkar D (2009a) Revisiting the agro-ecological zones for map evaluation. Indian J Genet Plant Breed 69:315–318 Pal DK, Bhattacharyya T, Chandran P, Ray SK (2009b) Tectonics–climate linked natural soil degradation and its impact in rainfed agriculture: Indian experience. In: Wani SP et al (eds) Rainfed agriculture: unlocking the potentials. CABI International, Oxfordshire, pp 54–72 Pal DK, Bhattacharyya T, Chandran P, Ray SK, Satyavathi PLA, Durge SL, Raja P, Maurya UK (2009c) Vertisols (cracking clay soils) in a climosequence of peninsular India: evidence for Holocene climate changes. Quat Int 209:6–21 Pal DK, Sarkar D, Bhattacharyya T, Datta SC, Chandran P, Ray SK (2013) Impact of climate change in soils of semi-arid tropics (SAT). In: Bhattacharyya et al (eds) Climate change and agriculture. Studium Press, New Delhi, pp 113–121 Pal DK, Bhattacharyya T, Sahrawat KL, Wani SP (2016) Natural chemical degradation of soils in the Indian semi-arid tropics and remedial measures. Curr Sci 110:1675–1682 Sehgal J, Mandal DK, Mandal C, Vadivelu S (1992) Agro ecological regions of India, 2nd edn. NBSS&LUP publication no. 24. National Bureau of Soil Survey and Land Use Planning, Nagpur, p 130 Smyth AJ, Dumanski J (1993) An international frame work for evaluating sustainable land management. World soil resource report 73, FAO, Rome Subramaniam AR (1983) Agro-ecological zones of India. Arch Met Geophys Bioclim Ser Bull 32:329–333 Tiwary P, Patil NG, Bhattacharyya T, Chandran P, Ray SK, Karthikeyan K, Sarkar D, Pal DK et al (2014) Pedotransfer functions: a tool for estimating hydraulic properties of two major soil types of India. Curr Sci 107:1431–1439 Velayutham M, Mandal DK, Mandal C, Sehgal J (1999) Agro ecological sub regions of India for planning and development, NBSS&LUP publication no. 35. National Bureau of Soil Survey and Land Use Planning, Nagpur, p 372

Chapter 3

Organic Carbon Sequestration and Ecosystem Service of Indian Tropical Soils

Abstract  To meet the great challenge of feeding the global population in the coming centuries by keeping soil health intact, global scientists are busy to find suitable ways to maintain soil organic carbon (SOC) in general and in tropical soils in particular. Both SOC and soil inorganic carbon (SIC) are the most important components of soil as they determine ecosystem and agroecosystem functions by influencing soil fertility, soil water, environment, microbial activity and other soil parameters. SOC also has a role in the global carbon cycle and in the mitigation of atmospheric levels of greenhouse gases (GHGs). SOC and SIC stock estimates of soils reported all over the world show their important roles for atmospheric CO2 sequestration. SOC stock (in the first 0–150 cm) of Indian soils is less (29.92 Pg) than that of SIC (33.98 Pg). Impoverishment in SOC in Indian soils is largely due to less accumulation of organic C (< 1%) in soils of the arid and semi-arid and dry subhumid climatic regions, which cover nearly 50 % of the total geographical area of India. But soils of humid tropical (HT) climates have >1% OC content. Factors responsible for organic carbon sequestration of Indian soils are identified to be (i) profuse vegetation under HT climate with adequate rainfall (>> 1000 mm) under cooler temperature for a period of a few months,(ii) presence of Ca-zeolites that ensure adequate soil moisture in both HT and semi-arid tropical (SAT) climate by preventing the total transformation of smectite to kaolinite, (iii) active inorganic part of soil as a substrate to build the SOC through clay-organic matter complex formation, and (iv) presence of smectites and vermiculites, which have the largest specific surface area and are capable of accumulating greater amounts of OC than the non-expanding minerals. Recent review on the impact of phyllosilicate mineralogy on SOC protection emphasizes that introducing a ‘phyllosilicate mineralogy’ parameter in SOC models appears premature. Alongside the phyllosilicates, clay fractions can also contain short range order minerals, metallic oxides and hydroxides and carbonates, which may have importance for SOC protection and their possible interaction with phyllosilicates. Major soil types of India contain a variety of clay minerals of expanding and non-expanding nature alongside interstratified or mixed layer ones. A revisit is necessary to highlight the nature and properties of crystalline expanding clay minerals and mixed clay minerals and also of associated non-crystalline ones that are likely to influence SOC sequestration in major soil orders. The ability of these types of minerals in SOC sequestration would enable © Springer Nature Switzerland AG 2019 D. K. Pal, Ecosystem Services and Tropical Soils of India, https://doi.org/10.1007/978-3-030-22711-1_3

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3  Organic Carbon Sequestration and Ecosystem Service of Indian Tropical Soils

soils for ecosystem services. Despite being a 0.7  nm mineral interstratified with hydroxy-interlayered smectite, HIS (kaolin), it shows a remarkable capacity to sequester more organic carbon (OC) than SAT Vertisols dominated by fairly well crystalline smectite. Research clearly points out the superior role of interstratified clay minerals such as kaolin than discrete smectite in OC sequestration. This unique example expands the basic knowledge on the role of kaolin in stabilization of SOC, which happens only under acidic pedochemical environment induced by profuse vegetation under HT climate. Therefore, both acidity and interstratified clay minerals appear to be more important factors of OC sequestration in HT soils. In addition, Ca-zeolite is an important factor in OC sequestration as it has high CEC and a large surface area and helped in forming kaolin by preventing complete transformation of smectite to kaolinite by maintaining relatively high base saturation level in acidic Vertisols, Mollisols and Alfisols but fails to enhance their clay CEC values beyond 50 cmol (p+) kg-1. The million years old Inceptisols, Alfisols, Mollisols and Ultisols of HT climate have considerable amount of SOC in the 0–30 cm depth that ranges from ~ 1% to 3.1%, which signifies a quasi-equilibrium value under natural forest. Long-term experiments (LTEs) in temperate humid region of UK indicated the SOC increase >7‰ year−1 and OC content in the 0–23 cm soil depth increased from ~1% to 2.14%, which is comparable to OC content of the HT soils of India and thus suggests that for HT soils, there is no immediate need to achieve the ‘4 per 1000’ goal. However, it may be necessary in SAT soils in view of high possibility of CO2 release from these soils under hostile SAT climatic conditions. In the Indian sub-continent, Andisols, Mollisols, Alfisols and Inceptisols of the HT climate under forest cover have sequestered maximum amount of OC, which may suggest that introduction of forestry by removing land from agricultural land uses may lead to large accumulations of SOC. Observations however indicate that even under natural forest in Indian SAT climate, red ferruginous Alfisols and Vertic Inceptisols over a century’s time could sequester high OC concentration of 1.78% and 0.81% in the 0–30 cm soil depth, respectively. But the conversion of agricultural lands to forestry has severe limitations if food security goals of the Indian sub-continent are to be met. Cropping systems involving crop rotation, agroforestry and mulching are better strategies for farmers in the tropic. Few studies on SAT ferruginous Alfisols and Vertisols indicate that horticultural system shows a better quasi-­equilibrium value of OC of 0.81% and 0.75% against 0.68% and 0.50% under agriculture system in the first 30 cm soil depth, respectively. Economic analysis on SOC sequestration reported that in majority of LTEs, the NPK plus FYM (10t ha−1) treatment showed higher SOC and also higher net return than that under NPK treatment, suggesting that application of FYM with NPK is a cost-effective, win-win technology for the Indian farmers. Paradoxically, the SOC content (0–30  cm depth) of an LTE of 28 years on SAT Vertisols using sorghum-wheat cropping system with recommended doses of NPK fertilizers plus FYM (10t ha−1) shows a value of 0.73% only. On the other hand, small but significant enhancement of OC content under horticultural system as compared to agricultural land uses is observed, which suggests that horticulture is a better option for SOC sequestration if forestry is not feasible in SAT red ferruginous Alfisols and Vertisols. It was noticed that the ­agricultural management practices

3.1 Introduction

31

advocated through the national agricultural research system (NARS) for the last several decades did not cause any decline in SOC in the major crop growing zones of the country under SAT climate. The increase in OC in agricultural soils (maximum up to ≤ 1% in 0–30 cm depth) observed in SAT areas through NARS interventions appears enough to provide ecosystem services in growing self-sufficiency in food production and food stock since independence. In fact, such interventions since post-Green Revolution period helped in increased OC sequestration in all soil types without leading to increased emissions of greenhouse gases (GHGs) to any alarming proportion. Among other ways to enhance the SOC stock of Indian SAT soils, conversion of soils with low productivity or that are fragile and prone to erosion, from agriculture to forest or grassland, may be a good strategy. Sodic soils are impoverished with OC but exhibit good potential to sequester OC when ameliorative management practices are implemented. Through the implementation of specific management practices for Typic Natrustalfs of IGP and Sodic Haplusterts of southern India, an increase in OC stock was observed for both soil types. Therefore, to include sodic soils as a potential option for C sequestration, additional financial support through incentives may be a viable option as soil C sequestration has proved to be the most cost-effective option as compared to geological sequestration. Further enhancement in SOC stock could be possible if the selected agricultural crops with more root volume are engineered by plant breeders. Greater release of carbonaceous acidic exudates from such crop roots would act as source of carbon. In addition, more soil acidity would also influence OC sequestration by breaking the crystalline clay structure to form short range order (SRO) minerals and hydroxy-interlayered clay minerals, which have high carbon sequestering potential. Keywords  Soil organic carbon · Factors of SOC sequestration · SOC quasi-­ equilibrium in humid tropical soils · Hydroxy-interlayered clay minerals and short range order minerals in SOC sequestration · Options to enhance SOC in SAT soils

3.1  Introduction Soils are well-known ecosystem service providers at local as well as global levels as they support forestry, agricultural and horticultural crops. At present a great challenge is to feed a global population in coming centuries, and to meet this demand, it is essential to maintain the health and productivity of soils under various land use practices even amidst climate change events. Soil carbon (both soil organic carbon, SOC, and soil inorganic carbon, SIC) being the most soil important component determines ecosystem and agroecosystem functions by influencing soil fertility, soil water, environment, microbial activity and other soil parameters. It has also a role in the global carbon cycle and the part it plays in the mitigation of atmospheric levels of greenhouse gases (GHGs), with special reference to C02 (Pal et  al. 2015; Bhattacharyya et al. 2017). SOC and SIC stock estimates of soils reported all over the world clearly brings out a fact that soil plays an important role for atmospheric CO2 sequestration (Batjes 2011; Powlson et  al. 2011; Banwart et  al. 2013;

32

3  Organic Carbon Sequestration and Ecosystem Service of Indian Tropical Soils

Bhattacharyya et al. 2014) and can thus act both as sources and sinks for carbon (Bhattacharyya et al. 2008). Serious research attempts are being made by the global scientists to find suitable ways to maintain and, wherever necessary, to increase the soil organic carbon, especially in tropical soils. Soils in the Asia/pacific region and sub-Saharan Africa are often reported to be impoverished in SOC and nutrient reserves and severely degraded (Lal 2011), which make about 90% of the 1020 million people food-insecure (FAO 2009a, b). Due to the climate change from wetter to dry climate, the increase in temperature and decrease in mean annual rainfall (MAR) is expected to cause further food insecurity in these regions. The crisis of both climate change and food insecurity can, however, be overcome by restoring the SOC pool and the concomitant improvement in soil quality. Among the several options to mitigate climate change (Jacobson 2009), the sequestration of C in agricultural soil is an important one (Lal 2011; Srinivasarao et al. 2013). A major part of the land area in India lies between the Tropic of Cancer and Tropic of Capricorn, and the soil therein is termed ‘tropical soil’. For a long time, tropical soils were perceived to be deep red and highly weathered soils of the hot and humid tropics only. In addition, they are often thought improperly to be either agriculturally poor or virtually useless (Sanchez 1976; Eswaran et al. 1992). India has five distinct bioclimatic systems (Bhattacharjee et al. 1982) with varying mean annual rainfall (MAR). The major soils of India are Vertisols, Mollisols, Alfisols, Ultisols, Aridisols, Inceptisols and Entisols covering 8.1%, 0.5%, 12.8%, 2.6%, 4.1%, 39.4% and 23.9%, respectively, of the total geographical area (TGA) of the country (Bhattacharyya et al. 2009). A recent review of Indian soils and their capacity to sequester organic and inorganic carbon in seven soil orders and the factors favouring C sequestration amidst nuances of pedogenesis and polygenesis due to tectonic, climatic and geomorphic episodes during the Holocene indicated the factors for the variability in SOC and SIC stocks of Indian soils vis-a-vis various land uses and productivity (Pal et al. 2015). The SOC, SIC and the total carbon (TC) stocks in seven soil orders indicate that the SOC stock (in the first 0–150 cm) of Indian soils is less (29.92 Pg) than that of SIC (33.98 Pg) (Table 3.1). The SOC and SIC stocks in the 0–30 cm depth in five bioclimatic zones of India (Table 3.2), however, indicate that SOC stocks are two times more than SIC stocks. Although the presence of CaCO3 (as SIC) in the humid and per-humid region is due to its inheritance from strongly calcareous parent material (Velayutham et al. 2000), the SIC stock in dry climate is relatively large (Bhattacharyya et al. 2000). In all soil orders, except the Ultisols, the SIC stock increases with soil depth (Table 3.1), indicating that most of the soil orders in India are affected by dry climatic conditions that cause more calcareousness in the subsoil (Pal et al. 2000a). The SOC stock of Indian soils stored in the upper 30 and 150  cm depths (Table 3.1) when compared to the stock for tropical regions and the world (Batjes 1996) shows that the share of Indian soils is not substantial (Table 3.3). The main reason is that there are very few OM-rich soils in India like Histosols, Spodosols, Andosols and Gelisols, and the area under Mollisols is relatively small, and Andosols are not mappable in 1:250,000 (Pal 2017). Moreover, the Indian soils cover only

33

3.1 Introduction Table 3.1  Carbon stock (in Pg = 1015 g) distribution by order in Indian soilsa Soil order Entisols Vertisols Inceptisols Aridisols Mollisols Alfisols Ultisols Total

Soil depth Range (cm) 0–30 0-150 0–30 0–150 0–30 0–150 0–30 0–150 0–30 0–150 0–30 0–150 0–30 0–150 0–30 0–150

Carbon stock (Pg) SOC SIC 0.62(6) 0.89(21) 2.56(8) 2.86(8) 2.59(27) 1.07(26) 8.77(29) 6.14(18) 2.17(23) 0.62(15) 5.81(19) 7.04(21) 0.74(8) 1.40(34) 2.02(7) 13.40(39) 0.09(1) 0.00 0.49(2) 0.07(0.2) 3.14(33) 0.16(4) 9.72(32) 4.48(13) 0.20(2) 0.00 0.55(2) 0.00 9.55 4.14 29.92 33.98

TC 1.51(11)b 5.42(8) 3.66(27) 14.90(23) 2.79(20) 12.85(20) 2.14(16) 15.42(24) 0.09(1) 0.56(1) 3.30(24) 14.20(22) 0.20(1) 0.55(1) 13.69 63.90

Adapted from Bhattacharyya et al. (2000) Parentheses show percentage of total SOC (soil organic carbon), SIC (soil inorganic carbon) and TC (total carbon, summation of SOC and SIC) a

b

Table 3.2  Soil organic and inorganic carbon stock (Pg, 0–30 cm) in different bioclimatic zones in Indiaa

Bioclimatic zone Cold arid Hot arid Semi-arid Subhumid Humid to per humid Coastal a

Area coverage (mha) 15.2 36.8 116.4 105.0 34.9 20.4

% of TGA 4.6 11.2 35.4 31.9 10.6 6.2

SOC

SIC

% of SOC Stock stock 0.6 6 0.4 4 2.8 30 2.4 26 2.0 21

Stock 0.7 1.0 2.0 0.33 0.04

1.3

0.07

13

TC % of SIC stock 17 25 47 8 1 2

Stock 1.3 1.4 4.8 2.73 2.04

% of TC stock 10 10 35 20 15

1.37

10

Adapted from Bhattacharyya et al. (2000, 2008)

11% of the total area of the world. Even under unfavourable environmental conditions for OC-rich soils, the SOC stocks of Indian soils demonstrate enough potential to sequester organic C. Impoverishment in SOC in Indian soils is largely due to less accumulation of organic C (< 1%) in soils of the arid and semi-arid and dry subhumid climatic regions (Velayutham et a. 2000), which cover nearly 50% of the TGA of India (Pal et al. 2000a). On the other hand, soils of humid tropical (HT) climates show their OC > 1% (Velayutham et al. 2000). These soils are not confined to a

34

3  Organic Carbon Sequestration and Ecosystem Service of Indian Tropical Soils

Table 3.3  Total SOC stock in India, tropical regions and the world (Pg)

SOC Soil organic Carbon (India)a Tropical regionsa Worldb SOC, India % of Tropical region Stock SOC stock % of World stock

0–30 cm

0–150 cm

9.55 201–203 684–724 4.72

29.92 616–640 2376–2456 4.77

1.4

1.2

Adapted from Bhattacharyya et al. (2000) Adapted from Batjes (1996), average values were taken

a

b

single production system and contribute substantially to India’s growing self-­ sufficiency in food production and food stock (Pal et al. 2015; Bhattacharyya et al. 2014). This has been made possible because of favourable natural endowment of soils that remained highly responsive to management interventions made mainly by farming communities with the support from national and international institutions. Factors responsible for organic carbon sequestration of Indian soils were recently identified (Pal et al. 2015) to be (a) profuse vegetation under HT climate with adequate rainfall (> > 1000 mm) and cooler temperature for a period of a few months (November–February), (b) presence of Ca-zeolites that ensures adequate soil moisture in both HT and semi-arid tropical (SAT) climate by preventing the total transformation of smectite to kaolinite, (c) active inorganic part of soil as a substrate to build the SOC through clay-organic matter complex formation and (d) presence of smectites and vermiculites that have the largest specific surface area and are capable of accumulating greater amounts of OC than the non-expanding minerals. And the main factor of inorganic carbon (SIC) sequestration in arid and SAT soils is the rapid calcification, which is the dominant pedogenic process that captures atmospheric CO2 for the formation of pedogenic CaCO3 in soils (Pal et al.2000a), and this aspect of C sequestration is dealt in details in Chap. 4. A recent review by Barre et al. (2014) on the impact of phyllosilicate mineralogy on SOC protection emphasizes that the different soil phyllosilicates have different properties that could lead to different ability to protect C, and the quality of phyllosilicate plays an important role for SOC protection (Lutfalle et al. 2018), but this has not been clearly established by more mechanistic studies. Barre et al. (2014), therefore, indicated that introducing a ‘phyllosilicate mineralogy’ parameter in SOC models appears premature. Moreover, their review suggests that alongside the phyllosilicates, clay fractions can contain also short range order minerals, metallic oxides and hydroxides and carbonates, which may have importance for SOC protection and their possible interaction with phyllosilicates, and thus it is a topic for further research.

3.2  Other Factors of SOC Sequestration

35

Sequestration of OC is considered to be a boon but the same for IC is a bane for soil health because the formation of SIC concomitantly induces sodicity and lowering of hydraulic properties of soils (Pal et al. 2000a). However, under improved management for SAT soils, the dissolution of CaCO3 makes soils more permeable to air and water and help in substantial gain in SOC (Wani et al. 2003; Pal et al. 2012a, b). Major soil types of India contain a variety of clay minerals of expanding and non-expanding nature alongside interstratified or mixed layer ones (Pal et al. 2000b; Pal 2017). This chapter revisits the nature and properties of crystalline expanding clay minerals, mixed clay minerals and also of associated non-crystalline ones, which, if present, are likely to influence SOC sequestration in major soil orders and their ability in SOC sequestration and ecosystem services.

3.2  Other Factors of SOC Sequestration Although the soil substrate quality in terms of quality and quantity of expanding clay minerals is conceived to be of fundamental importance in OC sequestration alongside dominating effect of HT climate with winter months aided by profuse vegetation, higher buildup of OC is not observed in smectitic SAT soils, in general (Pal et  al. 2015). This fact is explicit in smectitic Vertisols of India (developed in the alluvium of weathering Deccan basalt, Pal 2017) of the arid and SAT climates; they are actually impoverished in OC content ( 1%) (Table 3.4) (Bhattacharyya et al. 2005; Lal 2000). It is worth mentioning here that HT Vertisols, Mollisols and Alfisols are acidic, and their clay CEC values are   35    2 through the soil depth (Table.  5.1). These unique soil and mineralogical properties provide us novel insights as to how Ca-zeolites help in the formation and persistence of acidic Alfisols and Mollisols in HT climate for millions of years and discounted the hypothesis of Chesworth (1973, 1980) for the formation of Ultisols/Oxisols by nullifying the effect of parent material composition. Such examples of the formation of Alfisols and Mollisols under HT climate provide a deductive check on the inductive reasoning on the formation of tropical soils and also establish the validity of Jenny’s state factor equation in the formation of soils under intense weathering of humid tropical climate. The formation and persistence of Alfisols and Mollisols remain as a unique example of a steady state in soils developed over millions of years (Bhattacharyya et al. 1993; Chandran et al. 2005). These soils are in equilibrium with the present HT climate of the WG and KR areas until the climate changes further (Pal et al. 2012b; Pal 2017). Both WG and KR soils possess favourable soil properties, which are reflected in the enrichment of OC, adequate moisture, high BS and exchangeable Ca on soil exchange complex and moderately smectite-rich clays and also a better soil drainage. In these acidic soils especially those of Ratnagiri district of the Konkan region,

AWCb pH Organic Soil-CEC Depth Clay (1:2) carbon (%)c cmol(p+)kg−1 Horizon (cm) (%) COLEa (%) Pedon 6: Typic Argiudoll: Bhor, Pune, Western Ghats A 0–20 58 0.13 15 6.1 1.2 29 BW1 20–45 57 0.13 15 6.4 1.3 31 BW2 45–64 61 0.15 13 6.2 1.3 30 Bt 64–80 67 0.13 13 6.2 0.9 27 BC 80–110 65 ND6 13 6.2 0.6 27 Pedon 8: Rhodic Paleudalfs: Mahabaleshwar, Satara, Western Ghats A 0–25 53 0.08 12 5.5 2.0 16 Bt1 25–50 63 0.07 11 5.3 1.0 15 Bt2 50–90 67 0.07 11 5.1 1.2 16 BC1 90–128 65 0.09 10 5.4 0.8 16 BC2 128–161 65 0.10 10 5.6 0.9 15 BC3 161–190 63 0.10 10 5.5 0.3 14 Pedon 17: Typic Rhodudalfs: Udgiri, Kolhapur, Western Ghats A 0–20 49 0.11 12 5.4 2.2 14 BW1 20–47 48 0.09 13 5.1 0.9 12 BW2 47–72 46 0.08 11 5.0 0.7 12 BW3 72–100 48 0.09 10 5.0 0.6 12 Bt1 100–122 56 0.09 10 4.9 0.6 12 Bt2 122–140 57 0.09 10 4.9 0.4 12 Pedon 11: Typic Hapludalfs: Dapoli, Ratnagiri, Konkan Region A 0–15 47 0.08 11 5.3 2.0 13 Bt1 15–30 55 0.09 12 5.3 1.5 11 Sm/K

Sm/K

Sm/K

Sm/Kd

1.1 1.2 1.5 1.7 2.0 1.8

0.7 0.4 0.2 0.8 0.3 0.2

4.4 5.0

0.3 0.3 0.3 0.3 0.3 0.6

0.3 0.2 0.2 0.2 0.2 0.2

0.5 0.3 0.3 0.2 0.3 0.2 5.6 4.8 3.7 3.5 3.9 3.3

0.4 0.3 0.3 0.3 0.4 0.4

1.0 1.1 1.7 3.1 3.1 3.4

0.4 0.2 0.2 0.3 0.3

4.4 3.6 4.2 6.4 6.5 6.7

0.5 0.4 0.5 0.5 0.6

8.5 8.8 8.9 7.7 7.5

17.8 19.3 18.7 16.9 17.7

Dominant clay Extractable bases cmol(p+)kg−1 mineral by XRD method Ca Mg Na K

6.3 6.3

5.1 4.0 2.5 2.1 2.0 1.8

4.4 3.3 2.5 2.1 2.1 2.0

2.1 2.2 2.1 2.2 2.4

45 55

51 52 49 49 52 49

40 35 41 64 70 75

91 92 92 92 95

Exchangeable Base Ca/Mg saturation (%)

Table 5.1  Physical, chemical and mineralogical properties of representative acid red ferruginous soils of Western Ghats and Konkan Regions

70 5  Soil Modifiers (Ca-Zeolite and Gypsum) as Ecosystem Engineers in Soils of Humid…

11 13 14 14 13 11 Sm/K

b

a

4.4 5.3 5.0 6.1 6.7 5.8

0.7 1.0 1.6 2.5 2.5 2.2

2.2 2.4 2.5 2.4 1.8 1.8 0.3 0.3 0.3 0.3 0.4 0.4

0.5 0.4 0.4 0.4 0.4 0.9 0.2 0.2 0.2 0.2 0.2 0.2

0.2 0.2 0.2 0.2 0.2 0.2

7.5 7.1 7.0 8.1 8.3 7.2

13 14 14 14 13 13 Sm/K

Extractable bases cmol(p+)kg−1 Ca Mg Na K 5.6 1.6 0.3 0.2 4.8 2.5 0.3 0.2 4.6 2.3 0.3 0.2

Dominant clay mineral by Soil-CEC cmol(p+)kg−1 XRD method 11 11 9

COLE coefficient of linear expansion AWC available water content c Organic carbon values revised following Bhattacharyya et al. (2015b) d Sm/K = 0.7 nm mineral interstratified with hydroxy-interlayered smectite. (Adapted from Lal 2000)

AWCb pH Organic Depth Clay (1:2) carbon (%)c Horizon (cm) (%) COLEa (%) Bt2 30–58 55 0–11 11 5.5 0.9 BC1 58–90 46 0.09 11 5.6 0.8 BC2 90–120 38 0.09 10 5.9 0.6 Pedon 20: Dystric Eutrudept: Lanja, Ratnagiri, Konkan Region A 0–15 66 0.08 11 5.5 1.7 BW1 15–35 67 0.14 10 5.6 1.4 BW2 35–59 69 0.12 10 5.4 1.4 BC1 59–82 70 0.15 11 5.6 1.3 BC2 82–118 69 0.14 11 5.4 1.0 BC3 118–150 66 0.12 10 5.5 1.1 Pedon 21: Rhodic Paleudalfs: Lanja, Ratnagiri, Konkan Region A 0–13 46 0.09 13 5.6 2.4 Bt1 13–40 61 0.08 12 5.6 1.0 Bt2 40–68 68 0.12 13 5.0 0.7 Bt3 68–97 70 0.12 12 5.2 0.7 BC 97–126 68 0.14 12 5.5 0.7 Ccn 126–140 65 0.12 10 5.8 0.4 6.3 5.3 3.1 2.4 2.7 2.6

3.4 3.0 2.8 3.4 4.6 4.0

Exchangeable Ca/Mg 3.5 1.9 2.0

50 50 51 65 74 75

77 73 72 79 79 78

Base saturation (%) 67 71 78 5.2  Ca-Zeolites as Prolonged Ecosystem Engineer in Inceptisols, Alfisols… 71

72

5  Soil Modifiers (Ca-Zeolite and Gypsum) as Ecosystem Engineers in Soils of Humid…

Fig. 5.2  Representative scanning electron microscope photographs of (a) unweathered heulandite (Ca-zeolites) and (b) moderately weathered heulandite of red ferruginous soils of the Western Ghats and Konkan Region. (Adapted from Lal 2000)

crops do not show response to liming (Kadrekar 1979), and thus, lime is very rarely used in agricultural crops and also in mango orchards (Joshi et  al. 2015, 2016; Puranik et  al. 2016, 2017). Like most other fruit crops, mango prefers a slightly acidic soil. Lime is used as an amendment to raise the Ca2+ ions level in acid soils of India (Saadat and Gupta 2016) and elsewhere (Almeida et  al. 2012). However, acidic Inceptisols, Alfisols and Mollisols of the humid tropical WG and KR areas are deep, are clayey but are well drained and have enough Ca2+ ions level to defy the immediate need of lime addition. Ca2+ ion is the building block of plant cells and keeps the cell walls elastic and allows cells to expand as they grow, and it also improves fruit retention and produces weight and also increases shelf life. Therefore, the acidic Inceptisols, Alfisols and Mollisols of WG and KR areas do satisfy the above-mentioned mandatory soil parameters for profitable quality mango cultivation. In reality, these soils have significant ecosystem services as they have long supported the luxuriant forest vegetation, horticultural, cereal crops and spices (Sehgal 1998; Bhattacharyya et al. 2006; Pal et al. 2014). Thus, it would be imprudent to designate the acidic soils of WG and KR as chemically degraded soils as commonly conceived (ICAR-NAAS 2010). In view of the above discussion, it would be worthwhile to find an answer for how long the zeolitic acid soils are able to sustain such varied land uses without amending their acidity and when liming would be necessary on a time scale. It is difficult to envisage when such necessity would arise after the stocks of zeolites are depleted completely under continuing HT climate with concomitant phasing of acidic Alfisols and Mollisols towards the base-poor and OC-rich Ultisols (Pal et al. 2012b, 2014; Pal 2017). In addition, with the current knowledge, it is difficult to assign a time scale for when acidic Alfisols and Mollisols would phase towards Ultisols because of lack of selective method to quantify the heulandite (Ca-rich zeolite) content in soils which carry other clay minerals (Pal et al. 2013a). However, specific chemical methods were chosen by Bhattacharyya et al. (1999) to determine the CEC and extractable bases that sufficiently suggest the possible presence of zeolites in soils when the BS is in excess of 50 for acidic Alfisols/Mollisols/ Inceptisols and 100 for calcareous and slight to moderate alkaline Vertisols.

5.2  Ca-Zeolites as Prolonged Ecosystem Engineer in Inceptisols, Alfisols…

73

Fig. 5.3  Representative X-ray diffractogram (XRD) of fine clay (50% in general (Table 5.1), which suggests that acid soils at present are far from phasing towards Ultisols where BS 15 stands for reconsideration because soil degradation takes place even at low ESP in dilute solutions. Serious structural degradation of some Australian soils at an ESP as low as 6 was reported by Northcote and Skene (1972).Thereafter, many Australian soil researchers (Sumner 1995; Naidu et al. 1995) and from other countries such as Italy (Crescimanno et al. 1995) and India (Balpande et al. 1996; Pal et al. 2006) advocated that an ESP

96

6  Degradation in Indian Tropical Soils: A Commentary

much lower than 15 needs be used to denote the value above which a noticeable reduction in crop yields is observed due to the deterioration of physical properties of soils. Sodicity tolerance ratings of crops in loamy-textured soils of the IGP indicate that 50% reduction in relative rice yields was observed when ESP was above 50 and for wheat it was around 40 (Abrol and Fireman 1977). Since the reason for these apparently contrasting findings lay in the different values of solution concentration of the soils, Sumner (1995) opined that the establishment of a critical ESP threshold may be very arbitrary because properties exhibited by the so-called classic sodic soils are simply the upper end of a continuum of behaviour that extends across the full range of sodium saturations. The sodium saturations are increasingly dependent on reduced solution concentration. Sumner (1995) finally made a strong case to develop criteria based on dispersibility to characterize and predict the behaviour of soils with respect to infiltration, hydraulic conductivity and hard setting which will indicate the mechanisms of swelling and dispersion (Quirk and Schofield 1955; Shainberg et al. 1981). Naidu et  al. (1995) reported that the dispersibility of soils is the result of the interactive effects of clay content, nature of clay, cation suite, nature of soil solution compositions and organic matter. Gupta and Abrol (1990) highlighted the importance and contribution of swelling and dispersion to hydraulic properties of soils in terms of clay mineralogy at the species level, the ESP of the soil, the electrolyte concentration and nature of electrolytes in the soil solution. Although soils containing all other clays swell with changes in moisture content, changes are particularly extreme in smectite (Borchardt 1989). Through swelling and dispersion, the importance of smectite in impairing the hydraulic properties of soils was also highlighted when Vertisols (ESP  15 (Soil Survey Staff 1999) for sodic soils may have no practical relevance to their use and management. Under rainfed conditions, the yield of deep-rooted crops in Vertisols depends primarily on the amount of rain stored at depth in the soil profile and the extent to

6.3  Chemical Degradation in Indian HT and SAT Soils

97

which this soil water is released during crop growth between the rains. Moreover, both retention and release of soil water are governed by the nature and content of clay minerals and exchangeable cations. A significant positive correlation between available water content (AWC) and ESP (Pal et al. 2006) in sodic Vertisols without modifier indicates that although the soils can hold sufficient water, they do not support rainfed crops. In contrast, a non-significant correlation between AWC and ESP in sodic Vertisols with zeolites as modifiers indicates that despite having high ESP, these soils support rainfed crops (Pal et al. 2006, 2012). Therefore, fixing a lower limit for sodic subgroup of Vertisols either at ESP 5–15 or at ESP >15 may not reflect the impairment of drainage of soils. Characterizing such soils as sodic only on the basis of ESP may also mislead the end users of these soils. In view of the pedogenetic processes that ultimately impair the drainage of soils, evaluation of Vertisols for deep-rooted crops on the basis of sHC alone (Kadu et al. 2003) brought out a fact that an optimum yield of cotton in Vertisols of SAT part of Central India can be obtained when the soils are non-sodic (ESP   5) soils and with HC  > 1.30 ≤ 2.0, Tiwary et al. 2014 (Fig. 6.5) need to be kept out.

98

6  Degradation in Indian Tropical Soils: A Commentary

Fig. 6.3  Saturated hydraulic conductivity (sHC) map for the Indo-Gangetic Plains. (Adapted from Chandran et al. 2014)

6.3  Chemical Degradation in Indian HT and SAT Soils

99

Fig. 6.4  Saturated hydraulic conductivity map for the black soil region. (Adapted from Chandran et al. 2014)

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Fig. 6.5  Soil bulk density (0–30 cm) map developed for the Indo-Gangetic Plains. (Adapted from Chandran et al. 2014)

References Abrol IP (1982a) Reclamation of waste lands and world food prospects. In: Whither soil research, panel discussion papers, 12th International congress soil science, New Delhi, pp 317–337 Abrol IP (1982b) Reclamation and management of salt-affected soils. In: Review of soil research in India. Part 11, 12th International congress soil science, New Delhi, pp 635–654 Abrol IP, Fireman M (1977) Alkali and saline soils: identification and improvement for crop production, Bulletin no. 4. Central Soil Salinity Research Institute, Karnal Balpande SS, Deshpande SB, Pal DK (1996) Factors and processes of soil degradation in Vertisols of the Purna valley, Maharashtra, India. Land Degrad Dev 7:313–324 Balpande SS, Deshpande SB, Pal DK (1997) Plasmic fabric of Vertisols of the Purna Valley of India in relation to their cracking. J Indian Soc Soil Sci 45:553–562 Bhattacharyya T, Mukhopadhyay S, Baruah U, Chamuah GS (1998) Need for soil study to determine degradation and landscape stability. Curr Sci 74:42–47 Bhattacharyya T, Pal DK, Srivastava P (1999) Role of zeolites in persistence of high altitude ferruginous Alfisols of the Western Ghats, India. Geoderma 90:263–276 Bhattacharyya T, Pal DK, Srivastava P (2000) Formation of gibbsite in presence of 2:1 minerals: an example from Ultisols of Northeast India. Clay Miner 35:827–840 Bhattacharyya T, Pal DK, Lal S, Chandran P, Ray SK (2006) Formation and persistence of Mollisols on zeolitic Deccan basalt of humid tropical India. Geoderma 136:609–620 Bhattacharyya T, Babu Ram, Sarkar D, Mandal C, Dhyani BL, Nagar AP (2007) Soil loss and crop productivity model in humid tropical India. Curr Sci 93:1397–1403 Bhattacharyya T, Sarkar D, Sehgal JL, Velayutham M, Gajbhiye KS, Nagar AP, Nimkhedkar SS (2009) Soil taxonomic database of India and the states (1:250, 000 scale), NBSSLUP Publication no. 143. NBSS&LUP, Nagpur, India, 266 pp

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Bhattacharyya T, Ray SK, Chandran P, Karthikeyan K, Pal DK (2018) Soil quality and fibrous mineral in black soils of Maharashtra. Curr Sci 115:482–492 Borchardt G (1989) Smectites. In: Dixon JB, Weed SB (eds) Minerals in soil environments. Soil Science Society of America, Madison, pp 675–727 Buurman P, Van Lagen B, Velthorst EJ (1996) Manual of soil and water analysis. Backhuys Publishers, Leiden Chandran P, Ray SK, Bhattacharyya T, Dubey PN, Pal DK, Krishnan P (2004) Chemical and mineralogical characteristics of ferruginous soils of Goa. Clay Res 23:51–64 Chandran P, Ray SK, Bhattacharyya T, Srivastava P, Krishnan P, Pal DK (2005) Lateritic soils of Kerala, India: their mineralogy, genesis and taxonomy. Aust J Soil Res 43:839–852 Chandran P, Ray SK, Bhattacharyya T, Tiwari P, Sarkar D, Pal DK, Mandal C, Nimkar A, Maurya UK, Anantwar SG, Karthikeyan K, Dongare VT (2013) Calcareousness and subsoil sodicity in ferruginous Alfisols of southern India: an evidence of climate shift. Clay Res 32:114–126 Chandran P, Tiwary P, Mandal C, Prasad J, Ray SK, Sarkar D, Pal DK et al (2014) Development of soil and terrain digital database for major food-growing regions of India for resource planning. Curr Sci 107:1420–1430 Crescimanno G, Iovino M, Provenzano G (1995) Influence of salinity and sodicity on soil structural and hydraulic characteristics. Soil Sci Soc Am J 59:1701–1708 FAO (Food and Agriculture Organization of the United Nations) (1994) Land degradation in South Asia: its severity, causes and effects upon the people. World soil resources reports 78. FAO, Rome, Italy Gupta RK, Abrol IP (1990) Salt-affected soils: their reclamation and management for crop production. In: Stewart BA (ed) Advances in soil science, vol 11. Springer, Berlin, pp 223–288 Hall GF, Daniels RB, Foss JE (1982) Rates of soil formation and renewal in the USA. In: Schmidt BL (ed) Determinants of soil loss tolerance. ASA Publication No 45. American Society of Agronomy, Madison, pp 23–29 Harindranath CS, Venugopal KR, Raghu Mohan NG, Sehgal J, Velayutham MV (1999) Soils of Goa for optimising land use. NBSS Publication no. 74b (Soils of India Series), National Bureau of Soil Survey and Land Use Planning, Nagpur, India, 131 pp + 2 sheets of soil map on 1:500,000 scale Hilgard EW (1906) Soils: their formation, properties, composition and relation to climate and plant growth in the humid and arid regions. Macmillan, New York, 593 pp ICAR-NAAS (Indian Council of Agricultural Research- National Academy of Agricultural Sciences) (2010) Degraded and waste lands of India-status and spatial distribution. ICAR-­ NAAS. Published by the Indian Council of Agricultural Research, New Delhi, 56pp Jangra R, Gupta SR, Singh N (2015) Plant biomass, productivity, and carbon storage in ecologically restored grassland on a sodic soil in North-Western India. Indian J Sci 20:85–96 Jones RC, Hundall WH, Sakai WS (1982) Some highly weathered soils of Puerto Rico, 3. Mineralogy. Geoderma 27:75–137. https://doi.org/10.1016/0016-7061(82)90048-9 Kadu PR, Vaidya PH, Balpande SS, Satyavathi PLA, Pal DK (2003) Use of hydraulic conductivity to evaluate the suitability of Vertisols for deep-rooted crops in semi-arid parts of Central India. Soil Use Manag 19:208–216 Kassam AH, van Velthuizen GW, Fischer GW, Shah MM (1992) Agro-ecological land resource assessment for agricultural development planning: a case study of Kenya resources data base and land productivity. Land and Water Development Division, Food and Agriculture Organisation of the United Nations and International Institute for Applied System Analysis, Rome Krishnan P, Venugopal KR, Sehgal J (1996) Soil Resources of Kerala for land use planning. NBSS Publication no. 48b (Soils of India Series 10). National Bureau of Soil Survey and Land Use Planning, Nagpur, India, 54 pp + 2 sheets of soil map on 1:500,000 scale Lal R, Hall GF, Miller FP (1989) Soil degradation. I.  Basic processes. Land Degrad Rehabil 1:51–69 Lin H (2011) Three principles of soil change and pedogenesis in time and space. Soil Sci Soc Am J 75:2049–2070

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Mandal C, Mandal DK, Bhattacharyya T, Sarkar D, Pal DK et al (2014) Revisiting agro-ecological sub-regions of India-a case study of two major food production zones. Curr Sci 107:1519–1536 Millot G (1970) Geology of clays. Springer, New York Mohr ECJ, Van Baren FA, van Schuylenborgh J (1972) Tropical soils-a comprehensive study of their genesis. Mouton, The Hague Muggler CC (1998) Polygenetic Oxisols on tertiary surfaces, Minas Gerais, Brazil: soil genesis and landscape development (PhD thesis). Wageningen Agricultural University, The Netherlands Naidu R, Sumner ME, Rengasamy P (1995) National conference on sodic soils: summary and conclusions. In: Naidu R, Sumner ME, Rengasamy P (eds) Australian sodic soils: distribution, properties and management. CSIRO Publications, East Melbourne, pp 343–346 Natarajan A, Reddy PSA, Sehgal J, Velayutham M (1997) Soil Resources of Tamil Nadu for land use planning. NBSS Publication no. 46b (Soils of India Series). National Bureau of Soil Survey and Land Use Planning, Nagpur, India, 88 pp + 4 sheets of soil map on 1:500,000 scale Nayak DC, Sen TK, Chamuah GS, Sehgal JL (1996) Nature of soil acidity in some soils of Manipur. J Indian Soc Soil Sci 44:209–214 Northcote KH, Skene JKM (1972) Australian soils with saline and sodic properties, Soil publication no. 27. CSIRO, Melbourne Oldeman LR (ed) (1988) Global assessment of soil degradation (GLASOD). Guidelines for general assessment of status of human-induced soil degradation. ISRIC, Wageningen Pal DK (2017a) Degradation of red ferruginous soils of humid and semi-arid tropical climate - a critique. Adv Agric Res Technol J 1:14–18 Pal DK (2017b) A treatise of Indian and tropical soils. Springer, Cham Pal DK (2019) Simple methods to study pedology and edaphology of Indian tropical soils. Springer, Cham Pal DK, Deshpande SB, Venugopal KR, Kalbande AR (1989) Formation of di and trioctahedral smectite as an evidence for paleoclimatic changes in southern and central Peninsular India. Geoderma 45:175–184 Pal DK, Dasog GS, Vadivelu S, Ahuja RL, Bhattacharyya T (2000) Secondary calcium carbonate in soils of arid and semi-arid regions of India. In: Lal R et al (eds) Global climate change and pedogenic carbonates. Lewis Publishers, Boca Raton, pp 149–185 Pal DK, Balpande SS, Srivastava P (2001) Polygenetic Vertisols of the Purna Valley of Central India. Catena 43:231–249 Pal DK, Srivastava P, Bhattacharyya T (2003) Clay illuviation in calcareous soils of the semi-arid part of the Indo-Gangetic Plains, India. Geoderma 115:177–192 Pal DK, Bhattacharyya T, Ray SK, Chandran P, Srivastava P, Durge SL, Bhuse SR (2006) Significance of soil modifiers (Ca-zeolites and gypsum) in naturally degraded Vertisols of the Peninsular India in redefining the sodic soils. Geoderma 136:210–228 Pal DK, Bhattacharyya T, Chandran P, Ray SK (2009) Tectonics-climate-linked natural soil degradation and its impact in rainfed agriculture: Indian experience. In: Wani SP, Rockström J, Oweis T (eds) Rainfed agriculture: unlocking the potential. CABI International, Oxfordshire, pp 54–72 Pal DK, Wani SP, Sahrawat KL (2012) Vertisols of tropical Indian environments: pedology and edaphology. Geoderma 189–190:28–49 Pal DK, Sarkar D, Bhattacharyya T, Datta SC, Chandran P, Ray SK (2013) Impact of climate change in soils of semi-arid tropics (SAT). In: Bhattacharyya et al (eds) Climate change and agriculture. Studium Press, New Delhi, pp 113–121 Pal DK, Wani SP, Sahrawat KL, Srivastava P (2014) Red ferruginous soils of tropical Indian environments: a review of the pedogenic processes and its implications for edaphology. Catena 121:260–278. https://doi.org/10.1016/j.catena.2014.05.023 Pal DK, Bhattacharyya T, Sahrawat KL, Wani SP (2016) Natural chemical degradation of soils in the Indian semi-arid tropics and remedial measures. Curr Sci 110:1675–1682 Pathak P, Singh S, Sudi R (1987) Soil and water management alternatives for increased productivity on SAT Alfisols. Soil conservation and productivity. In: Proceedings IV International conference on soil conservation, Maracay-Venezuela, November 3–9, 1985, pp 533–550

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Pathak P, Sudi R, Wani SP, Sahrawat KL (2013) Hydrological behaviour of Alfisols and Vertisols in the semi-arid zone: implications for soil and water management. Agric Water Manag 118:12–21 Quirk JP, Schofield RK (1955) The effect of electrolyte concentration on soil permeability. J Soil Sci 6:163–178 Rao DLN, Ghai SK (1985) Urease and dehydrogenase activity of alkali and reclaimed soils. Aust J Soil Res 23:661–665 Reza SK, Baruah U, Nayak DC, Dutta D, Singh SK (2018) Effect of land use on soil physical, chemical and microbial properties in humid subtropical northeastern India. Natl Acad Sci Lett. https://doi.org/10.1007/s40009-018-0634-1 Sehgal JL (1998) Red and lateritic soils: an overview. In: Sehgal J, Blum WE, Gajbhiye KS (eds) Red and lateritic soils. Managing red and lateritic soils for sustainable agriculture 1. Oxford and IBH Publishing, New Delhi, pp 3–10 Sehgal JL, Abrol IP (1992) Land degradation status: India. Desertification Control Bull 21:24–31 Sehgal JL, Abrol IP (1994) Soil degradation in India: status and impact. Oxford & IBH Publishing, New Delhi Sen TK, Nayak DC, Singh RS, Dubey PN, Maji AK, Chamuah GS, Sehgal JL (1997) Pedology and edaphology of benchmark acid soils of North-Eastern India. J Indian Soc Soil Sci 45:782–790 Shainberg I, Rhoades JD, Prather RJ (1981) Effect of low electrolyte concentration on clay dispersion and hydraulic conductivity of a sodic soil. Soil Sci Soc Am J 45:273–277 Shiva Prasad CR, Reddy PSA, Sehgal J, Velayutham M (1998) Soils of Karnataka for optimising land use. NBSS Publication no. 47b (Soils of India Series), National Bureau of Soil Survey and Land Use Planning, Nagpur, India, 111 pp + 4 sheets of soil map on 1: 500,000 scale Sidhu GS, Bhattacharyya T, Sarkar D, Chandran P, Pal DK et al (2014) Impact of management levels and land-use changes on soil properties in rice-wheat cropping system of the Indo-Gangetic Plains. Curr Sci 107:1487–1501 Smeck NE, Runge ECA, Mackintosh EE (1983) Dynamics and genetic modelling of soil system. In: Wilding LP, Smeck NE, Hall GF (eds) Pedogenesis and soil taxonomy-concepts and interactions. Developments in Soil Science II-A. Elsevier, Amsterdam, pp 51–81 Smith GD (1986) The Guy Smith interviews: rationale for concept in Soil Taxonomy. SMSS Technical Monograph 11. SMSS, SCS, USDA, USA Soil Survey Staff (1999) Soil taxonomy: a basic system of soil classification for making and interpreting soil surveys. United States Department of Agriculture, Natural Resource Conservation Service, Agriculture Handbook No. 436, U.S. Government Printing Office, Washington, DC Srivastava P, Pal DK, Aruche KM, Wani SP, Sahrawat KL (2015) Soils of the Indo-Gangetic Plains: a pedogenic response to landscape stability, climatic variability and anthropogenic activity during the Holocene. Earth-Sci Rev 140:54–71. https://doi.org/10.1016/j.earscirev.2014.10.010 Sumner ME (1995) Sodic soils: new perspectives. In: Naidu R, Sumner ME, Rengasamy P (eds) Australian sodic soils: distribution, properties and management. CSIRO Publications, East Melbourne, pp 1–34 Tiwary P, Patil NG, Bhattacharyya T, Chandran P, Ray SK, Karthikeyan K, Sarkar D, Pal DK et al (2014) Pedotransfer functions: a tool for estimating hydraulic properties of two major soil types of India. Curr Sci 107:1431–1439 UNEP (1992) World atlas of desertification. Edward Arnold, London Vaidya PH, Pal DK (2002) Micro topography as a factor in the degradation of Vertisols in Central India. Land Degrad Dev 13:429–445 Varghese T, Byju G (1993) Laterite soils, Technical monograph no. 1. State Committee on Science, Technology and Environment. Government of Kerala, Kerala, India Velayutham MV, Pal DK (2016) Soil resilience and sustainability of semi-arid and humid tropical soils of India: a commentary. Agropedology 26:1–9 Wani SP, Pathak P, Jangawad LS, Eswaran H, Singh P (2003) Improved management of Vertisols in the semi-arid tropics for increased productivity and soil carbon sequestration. Soil Use Manag 19:217–222 Zade SP, Chandran P, Pal DK (2017) Role of calcium carbonate and palygorskite in enhancing exchangeable magnesium to impair drainage of Vertisols of semi-arid western India. Clay Res 36:33–45

Chapter 7

Summary and Concluding Remarks

Abstract  Soils have a remarkable role in providing ecosystem services which are very often overlooked by the soil scientists. Indian soil scientists developed state-of-­ the-art information in the last decade on tropical soils of India and argued with both scientific and economic rigour that soils have a paramount role to play in ecosystem services. Although such valuable work has been done on Indian tropical soils, it has always been difficult to manage these soils to sustain their productivity because some unique soil properties are yet to be linked explicitly to soil ecosystem services. The inclusion of soils in ecosystem services frameworks and policy- and decision-­ making needs to happen effectively so that soil science emerges as a ‘forward-­ looking field of science’. Soil care needs to be a constant research endeavour in Indian tropical environment so that gaps between food production and future population growth can be filled. Therefore, it would be interesting to follow how lower-­ level ecosystem services could be linked to soil properties of Indian tropical soils. This chapter highlights some important soil property-driven ecosystem services of Indian tropical soils (as discussed in Chaps. 2, 3, 4, 5 and 6) that aim at facilitating a re-evaluation of the soil ecosystem services with adequate attention and care. Keywords  Indian tropical soils · Key soil properties · Ecosystem services Soils are the most complex and important biomaterials and have an outstanding role in providing ecosystem services to mankind. But adequate recognition of this fact is seldom highlighted in an appropriate manner, and this is probably the main reason why soil science still appears be an inward-looking field of science. For the last several decades, many thought the tropical soils to be deep and highly weathered soils, which are either agriculturally poor or practically useless. A formidable research effort by Indian soil scientists in the last decade has focused on delineating novel insights on the properties of tropical soils in India and thereby worked to remove these misunderstandings. Their work has definitively shown that soils are one of the important determinants of India’s economic status. Thus, inclusion of soils in ecosystem services frameworks and policy- and decision-making needs to be highlighted. Renewed research in this direction is warranted because most research attempts so far made to evaluate the ecosystem services did not give © Springer Nature Switzerland AG 2019 D. K. Pal, Ecosystem Services and Tropical Soils of India, https://doi.org/10.1007/978-3-030-22711-1_7

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adequate attention to the soil component. Ecosystem services are defined and classified differently, and they are often observed to be context specific. They are divided into lower-level services such as food, fibre, water supply and aesthetic values. Although much valuable work has been done on Indian tropical soils, it has been always difficult to manage these soils to sustain their productivity because unique soil properties were rarely linked explicitly to soil ecosystem services. Therefore, soil care needs to be a constant research endeavour in the Indian tropical environment as new soil knowledge base becomes critical when attempts are made to fill the gap between food production and future population growth. Realizing this urgency, scientific ventures during the last few decades on benchmark and identified soil series by the Indian pedologists were made to provide insights into several aspects of five pedogenetically important soil orders like Alfisols, Mollisols, Ultisols, Vertisols and Inceptisols of tropical Indian environments. It is now possible to follow how lower-­level services could be linked to the Indian tropical soils. Global distribution of tropical soils and the recent advances in knowledge by studying them in the Indian sub-continent now await a link between soil properties and ecosystem services for enhancing crop productivity and maintaining soil health in the twenty-first century. To establish the unique role of soil properties in ecosystem services of Indian tropical soils, some important lower-level ecosystem services were selected and discussed in the various chapters in this book. Concluding perspectives on each of these topics has been highlighted below.

7.1  Agro-ecological Regions as a Tool for Ecosystem Services The slow progress in irrigation facilities is impeding the crop production in 140 m ha of Indian arable land and not taking place at the expected speed at present. An improvement of the water productivity of rainfed situation holds a promise to increase the crop productivity because the semi-arid tropical (SAT) regions show a large gap between farmers’ yield and achievable yield. The present gap between farmers’ yield and achievable yield can be filled by adopting sustainable natural resource management. In order to achieve this goal, there is a need to create near homogeneous soil-climatic regions in the form of agro-ecological zones (AEZ). The AEZ made on FAO/UNESCO global soil and terrain map of 1:5000,000 scales by Indian researchers as an ecosystem service provider is very broad and poses challenges for crop planning, both at state and district levels. Subsequently, several attempts were made by the ICAR-NBSS &LUP including the refinement of AEZ to divide 20 agro-ecological regions (AER) into 60 agro-ecological subregions (AESRs) in 1999. The usefulness of 60 AESRs as ecosystem services was realized on few occasions, but further research became necessary to refine the AESR boundaries in the SAT climate, where rainfall could be matched with the crop water requirement. Collection of antecedent soil moisture, after the cessation of rains when rainfall (P) falls short of 0.5 potential evapotranspiration (PE), becomes an essential requirement because in its absence, the present AESR boundaries vis-à-vis

7.2  Organic Carbon Sequestration and Ecosystem Service

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crop performance exhibit scenarios a little away from reality in SAT areas. The soil moisture dynamics are greatly influenced by saturated hydraulic conductivity (sHC), which in turn is affected by exchangeable sodium percentage (ESP) besides gypsum, Ca-rich zeolites and palygorskite. Instead of following the FAO method for calculating the length of growing period (LGP) from monthly/decadal precipitation (P) and potential evapotranspiration (PET), available water holding capacity (AWC) of shrink-swell soils (BSR) was computed considering the available water of all the soil layers to a depth of 1 m or up to least permeable layer (sHC < 10 mm h−1). Some of the measured sHC of the pedons indicated that it rapidly decreases with depth, even though the clay content with soil depth is almost uniform. This suggests that there is a need for correcting LGP and in turn AESRs, based on quantitative values of soil drainage, i.e. sHC data of soils. The spatio-temporal information on sHC and soil water retention-release behaviour is essential for crop and land use planning in SAT areas. For the Indo-Gangetic Plains (IGP) soils, the sHC is affected by the increased subsoil bulk density due to intensive cultivation. In the BSR, the presence of Na+ and Mg++ ions affects the drainage, water retention and release behaviour of the soils. Modifications of the AESR maps of the IGP and BSR are based on newly acquired soil resource database and revised LGP class linked with crop performance. Following this unique method, 17 AESRs of IGP and 27 AESRs of BSR were re-delineated into 29 and 45 subregions, respectively. The observed compatibility between revised LGP and cotton yields in shrink-swell soils was observed. In view of their ecosystem capacity building to provide multiple biophysical and crop yield benefits, the modified AESRs stand as an effective ecosystem service provider of SAT soils. The soil property-driven revised AESR delineations thus add a unique value to the soil ecosystem services and can also act as a technology transfer tool for agricultural land use planning at the national and regional level.

7.2  Organic Carbon Sequestration and Ecosystem Service World scientists are engaged in finding suitable ways to maintain or increase soil organic carbon (SOC) in general and in tropical soils, in particular. Both SOC and soil inorganic carbon (SIC) are the most soil important components in ecosystem and agroecosystem functions as they influence soil fertility, soil water, environment and microbial activity. SOC and SIC stock estimates reported all over the world show their importance in atmospheric CO2 sequestration. SOC stock (29.92 Pg in the first 0–150 cm) of Indian soils is less than that of SIC (33.98 Pg), and it is largely due to less accumulation of organic C (< 1%) in soils of the arid and semi-arid and dry subhumid climatic regions, which are of poor OC content. In contrast, the soils of humid tropical (HT) climates show their OC > 1%. Factors for OC sequestration of Indian soils are (i) profuse vegetation under HT climate with adequate rainfall (> > 1000 mm) under cooler temperature for a period of a few months, (ii) presence of Ca-zeolites that ensures adequate soil moisture in both HT and semi-arid tropical (SAT) climates by preventing the total transformation of smectite to kaolinite and

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(iii) active inorganic part of soil as a substrate to build the SOC through clay-organic matter complex formation, and the presence of 2:1 expanding clay minerals. However, a recent review on the function of phyllosilicate minerals on SOC protection suggests that introducing a ‘phyllosilicate mineralogy’ parameter in SOC models appears to be inappropriate because soils contain not only the phyllosilicates but also contain short range order minerals, metallic oxides and hydroxides and carbonates, which may have roles in SOC protection. Major soil types of India contain a variety of expanding to non-expanding clay minerals alongside interstratified or mixed layer ones and non-crystalline clay minerals. The ability of these types of minerals in SOC sequestration would enable soils for ecosystem services. Despite being a 0.7 nm clay mineral interstratified with hydroxy-interlayered smectite, HIS (kaolin) shows a remarkable capacity to sequester more OC in HT soils than SAT Vertisols dominated by discrete smectite, suggesting the superior role of kaolin than discrete 2:1 expanding clay mineral in OC sequestration. The formation of kaolin happens only under acidic pedochemical environment induced by profuse vegetation under HT climate. Therefore, both acidity and interstratified clay minerals appear to be more important factors of OC sequestration in HT soils. In addition, Ca-zeolite is an important factor in OC sequestration as it has high CEC and a large surface area and prevented complete transformation of smectite to kaolinite by maintaining relatively high base saturation level in OC-rich and acidic Vertisols, Mollisols and Alfisols. SOC in the 0–30 cm depth of million-year-old Inceptisols, Alfisols, Mollisols and Ultisols of HT climate ranges from ~ 1% to 3.1%, which has reached a quasi-equilibrium value under natural forestation. Long-term experiments (LTEs) in temperate humid region of the UK indicated the SOC increase >7‰ year−1 and OC content in the 0–23 cm soil depth increased from ~1% to 2.14%, which is comparable to the HT soils of India. The OC enrichment suggests no immediate need to achieve the ‘4 per 1000’ goal in Indian HT soils, but it may be necessary in SAT soils. The favourable OC enrichment in Indian HT soils under forest cover such as Andisols, Mollisols, Alfisols and Inceptisols suggests that introduction of forestry by removing land from agricultural land uses may lead to large accumulations of OC in soil. But the idea of conversion of agricultural lands to forestry is constrained by the fact that the food security goals of the Indian sub-­ continent will not be achieved. Economic analysis on SOC sequestration reported that in majority of LTEs, the NPK plus FYM (10 t ha−1) treatment showed higher SOC and also higher net return than that under NPK treatment, suggesting that application of FYM with NPK is a cost-effective, win-win technology for Indian farmers. But the SOC content (0–30  cm depth) of an LTE of 28 years on SAT Vertisols using sorghum-wheat cropping system with recommended doses of NPK fertilizers plus FYM (10 t ha−1) shows a value of 0.73% only. On the other hand, significant enhancement of OC content under horticultural system as compared to agricultural land uses is observed. This may suggest that horticulture is a better option for SOC sequestration if forestry is not feasible in SAT red and black soils. The management practices advocated through the national agricultural research system (NARS) for the last several decades did not cause any decline in SOC of SAT soils in the major crop growing zones of the country. Interestingly, the OC increase

7.3  Soil Inorganic Carbon Sequestration in Soil Ecosystem Services

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(maximum up to ≤1% in 0–30 cm depth) in agricultural SAT soils appears enough to provide ecosystem services in growing self-sufficiency in food production and food stocks since independence without leading to increased emissions of greenhouse gases to any alarming proportion. Among other ways to enhance the SOC stock of Indian SAT soils, reclamation of 3.7 m ha of sodic soils could be taken up, which exhibit good potential to sequester OC. Therefore, to include sodic soils as a potential option for C sequestration has proved to be the most cost-effective option. Further enhancement in SOC stock could be possible if the selected agricultural crops with more root volume are engineered by plant breeders. Greater release of carbonaceous acidic exudates from such crop roots would act as a source of carbon. In addition, more soil acidity would also influence OC sequestration by breaking the crystalline clay structure to form short range order (SRO) minerals and hydroxy-­ interlayered clay minerals, which have high carbon sequestering potential.

7.3  S  oil Inorganic Carbon Sequestration in Soil Ecosystem Services Various estimates of the world storage of SOC are available, but there is very little effort to estimate the carbon stored in inorganic form, primarily as CaCO3 even though the large quantities of SIC play an important role in global carbon cycle. Calcareous soils of India occupy an area of 228.8 m ha and cover 69.4% of the total geographical area (TGA) and spread over 38 out of 60 agro-ecological subregions, and the SIC stock is around 33.94Pg in the first 0–1.5 m depth. The SIC stock is mainly due to pedogenic formation of CaCO3 (PC) in SAT soils, which have an adverse effect on soil productivity. Higher amount of SOC stock (9.55Pg) than SIC (4.14Pg) in the first 0–0.3  m depth suggests that the shallow-rooted agricultural crops played a unique role in enhancing the OC concentration in the rhizosphere where the formation of PC was slowed down. This is an important factor in rainfed agriculture in SAT environments. Current productivity of farmers’ fields in the rainfed tropics is two- to fourfold lower than the achievable crop yields. The arid and semi-arid environments cover more than 50% of the total geographical area of India, and the soils under such areas are, by and large, used for rainfed agriculture. In dry climates, the primary pedogenic process is calcification, which deprives soils of Ca2+ ions both in solution and on exchange complex. Due to the lack of adequate Ca2+ ions, both physical and chemical properties of soils are modified and cause reduction in crop yield. However, in view of the present soil productivity of calcareous SAT soils as evidenced from their support in India’s growing self-sufficiency in food production, a critical review is warranted to establish the function of SIC in the soil ecosystem services during the cultural practices of agricultural crops. The presence of PC is common in major soil types of semi-arid tropical (SAT) India (alluvial soils of the Indo-Gangetic Plains, IGP, red ferruginous soils and shrink-swell soils), but its formation causes chemical degradation in soils as evidenced from the rise in pH, relative abundance of Na+ ions on soil exchange sites and the solution and

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dispersion of the fine clay particles. Na+-enriched chemical environment creates conditions conducive for the deflocculation of clay particles and their subsequent movement downwards. Thus, the formation of PC and the clay illuviation represent two concurrent and contemporary pedogenetic events, which eventually cause an increase in the sodium adsorption ratio (SAR) and the exchangeable sodium percentage (ESP) and pH values with depth, representing a pedogenic threshold during the dry climates of the Holocene. Although the formation of PC is considered as the basic natural degradation process, exhibiting the regressive pedogenesis, it captures atmospheric CO2 and immobilizes C in unavailable form in soils, which retards the emission of CO2 from SAT soils. Due to regressive pedogenesis in SAT environment, soils become calcareous and sodic and thus lose their productivity. To make such soils resilient, land resource managers are always in search of innovative methods that can restore the required balance between exchangeable and water-soluble Ca2+ ions in these soils. Use of remote sensing technique to map areas under sodic soils in the north-western (NW) parts of the IGP becomes easy as soils show salt-efflorescence in the surface as an evidence of soil sodicity. But such technique is of no help to map the non-zeolitic and non-gypsiferous Vertisols with poor drainage (sHC < 10 mm h−1) even at ESP >5 < 15 and poor crop productivity, because of the absence of salt-efflorescence in the soil surface. According to the criteria of the US Salinity Laboratory, such Vertisols do not qualify as sodic soils. Therefore, the reclamation technology developed by the Indian Council of Agricultural Research-Central Soil Salinity Research Institute (ICAR-CSSRI), Karnal, remained inaccessible to this kind of poorly drained and agriculturally less productive soils. Vertisols, which are impoverished in OC and rich in CaCO3, show enough resilience under improved management (IM) system of the International Crops Research Institute for Semi-Arid Tropics (ICRISAT) that does not include any amendment like gypsum and FYM. Physical, chemical and biological properties of soils were improved after following the IM system to the extent that a poorly drained black soil (Sodic Haplusterts) can now qualify for well-drained soils (Typic Haplusterts). Such remarkable improvement in soil properties was possible through the continuous release of higher amount of Ca2+ ions during the dissolution of CaCO3, compared to slower rate of formation of CaCO3. Dissolution of CaCO3 provided enough soluble Ca2+ ions to replace unfavourable Na+ ions on the soil exchange sites and also caused higher exchangeable Ca/Mg ratio in soils under IM system. Enhanced Ca/Mg ratio improved the sHC for better storage and release of soil water during dry spell between rains and helped in better crop productivity as well as higher OC sequestration. The observed improvement in Vertisols’ sustainability suggests that the IM system is capable of mitigating the adverse effect of climate change. Although the IM system is slow as compared to gypsum-aided one, it is truly a cost-effective and farmer-friendly. This technology makes soil researchers aware of the benefit of the presence of CaCO3 as a hidden treasure or as an ecosystem engineer during the reclamation of sodic soils. Role of SIC as ecosystem engineer is also evidenced during the reclamation processes of IGP sodic soils (Natrustalfs) even in presence of chemical amendment such as gypsum. After their reclamation of Natrustalfs, the morphological, physical and chemi-

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cal properties of soils improved so much that the soils were reclassified as well-drained and OC-rich normal Alfisols (Haplustalfs). The fulfilment of Ca saturation was possible by the dissolution of PC during the growing of the rice crop under submerged conditions. The rate of dissolution of PC was much higher than its rate of formation in the top 1 m soil depth. Resilience of sodic soils of NW parts of the IGP through the dissolution of PC was also realized under protection of naturally occurring grassland system over a long period (1970–2006). Under grasslands, the released acidic root exudates dissolved PC, and the released Ca2+ ions caused a remarkable reduction in pH and ECe and enhanced OC concentration in the surface horizons. Similar improvement in soil properties including the biological activity of the IGP sodic soils under growing trees was also observed at the expense of dissolution of PC. Even after becoming normal soils as Haplustalfs and Haplusterts both IGP and Vertisols still contain moderate amount of CaCO3. It is quite likely that Ca2+ion-enriched chemical environment would not allow Haplustalfs and Haplusterts to transform to any other soil order so long CaCO3 remains as a soil modifier. The unique ecosystem services of SIC show enough potential to cause an enhancement in the present SOC stock of Indian soils beyond 30 Pg.

7.4  Soil Modifiers as Ecosystem Engineers A few decades ago, the unique role of soil modifiers (Ca-zeolites and gypsum) in Indian tropical soils in fine-tuning the exiting soil classification scheme and the management practices to enhance and sustain the soils’ productivity was reported by the researchers of the Indian Council of Agricultural Research-National Bureau of Soil Survey and Land Use Planning (ICAR-NBSS&LUP), Nagpur. But their roles in ecosystem services as both sustained and temporary ecosystem engineers did not get the required attention. A hypothesis on the unique role of Ca-zeolites (heulandite) was proposed in early 1990 on the formation and persistence of several million-year-old acidic and OC-rich ferruginous Inceptisols, Alfisols and Mollisols in intense leaching environment of humid tropical (HT) climate on the Deccan basalt rock system in two selected districts of the Western Ghats of Maharashtra and in the Satpura ranges of Madhya Pradesh. The formation and persistence of million-­ year-­old acid soils then led soil researchers to hypothesize that the favourable release of Ca2+ ions from heulandite (Ca-zeolites) prevented the progressive pedogenesis towards the formation of kaolinitic/gibbsitic Ultisols/Oxisols, arrested the soils from losing their productivity and also indicated the ability of Ca-zeolites as prolonged ecosystem engineers. This hypothesis has recently been validated by observing their presence in similar soils of other districts of the Western Ghats (WG) and the Konkan Region (KR) where Ca-zeolites are providing a sustained ecosystem services to agriculture, horticulture and forestry enterprises in other districts of WG and KR, representing the Deccan basalt geology. In semi-arid tropical (SAT) environment, Ca-zeolites exhibit their ecosystem services by creating a favourable drainage even amidst sodicity in Vertisols and help in redefining sodic

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7  Summary and Concluding Remarks

soils. In addition, they support good agricultural practices by retaining NH4+ions in their crystal structure and releasing K ions into soil solution and not by fixing solution P. But in some SAT Vertisols, Ca-zeolites behaved like transitory ecosystem engineers as they could not prevent the rigourousness of regressive pedogenesis, which caused more calcareousness and sodicity. In contrast, gypsum as a soil modifier could arrest the development of sodicity in SAT Vertisols by providing enough soluble Ca2+ ions which helped to overcome the ill effects of regressive pedogenesis and also made soils more productive for agriculture. The present sustainability of crop productivity in SAT Vertisols will continue further as gypsum becomes available as a better ecosystem engineer than Ca-zeolites.

7.5  Degradation in Indian Tropical Soils Land and soil degradation are often projected to be an effect of only anthropogenic processes although both land and soil degradation are caused by natural and human-­ induced processes. It has always been a national endeavour to record the area of the severity and extent of soil degradation in the country. The earliest assessment of the area under land degradation was made by the National Commission on Agriculture at 148 mha, followed by 175 m ha by the Ministry of Agriculture. The ICAR-NBSS &LUP projected an area of 187 m ha as degraded lands in 1994. It was revised in 2004, and the area was re-estimated at 147 m ha in contrast to the estimate of 123 m ha by the National Wasteland Development Board. In view of different estimates, the National Academy of Agricultural Sciences (NAAS) took a leadership role to bring all the concerned agencies together to achieve a harmonized classification system comprising wasteland classes and soil degradation. A map was prepared, and the total area under degraded and wastelands in the country was estimated to be at 114.01  mha, projecting the areas under water erosion, wind erosion, chemical degradation (salinization/alkalinization and acidification), salt-affected soils and acid soils. It is paradoxical how the area (114.01 mha) under soil degradation and the area of ~141 m ha under arable land can fulfil the country’s relentless endeavour to sustain food stock and self-sufficiency in food grain production. This strongly suggests that the estimates on different forms of soil degradation are not entirely based on sound science. Water erosion is the most widespread form of soil degradation in India especially in the red ferruginous (RF) soils of both humid tropical (HT) and SAT climates, and its estimates appear that it was done without assigning due weightage to the rate of top soil formation HT soils of north-eastern hills (NEH) and western, central and southern peninsular areas. The operative pedogenic processes that are linked to soil/crop productivity need to be assessed prior to an estimation of the land areas under water erosion and chemical degradation. In view of remarkable anomalies observed between the observed potential of soil productivity and the projection on the extent of soil erosion hazards in soils of both SAT and HT climates, and also designating productive acid soils as degraded soils, a critical appraisal is necessary to confirm their degradation status. Similarly, sodic soils show enough

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resilience even under prolonged natural vegetative cover and also after typical shortterm management interventions, suggesting that sodification is not an irreversible pedogenic process to cause a permanent senility in soils. It would be prudent to keep these soils out of degraded class so that the present projected area under degradation status can be reduced and made compatible with the nation’s aspiration of food stock and food grain production. Formation of matured soils in HT climate justifies well the existence of Ultisols, Alfisols, Mollisols and clay-enriched Inceptisols on a stable landscape in some states of NEH areas, Goa, Maharashtra, Madhya Pradesh, Karnataka and Andaman and Nicobar Islands, which have no major issue of water erosion. This is also supported by their OC concentration ~ 1–3% in the 0–30 cm of the soil depth effected through the addition of C by litter falls and its accumulation as soil organic matter under adequate vegetation and climate. In addition, such soils do not represent nutrient impoverished kaolinitic/gibbsitic soils of most advanced weathering stage. On the contrary, they demonstrate their unique ecosystem services. RF soils occurring under SAT environments in the southern states of Karnataka, Andhra Pradesh and Tamil Nadu are reported to suffer from soil loss due to water erosion at the rate of >10 t ha−1 year−1 as the threshold for soil degradation. But the RF soils of SAT are dominantly matured soils like Alfisols followed by Mollisols. In view of their operative pedogenic processes, such matured soils may not have any major problem of soil loss due to water erosion. The experimental studies on RF soils under successful agricultural production system do not suffer from any major soil loss and are also capable of providing ecosystem services. The threshold value of soil loss by water erosion as a sign of degradation needs to be based on pedogenesis and experimental results. An arbitrary value of >10 t ha−1 year−1 would be an inappropriate approach that is to be wisely avoided to prevent the unnecessary financial burden for the current and future conservation measures.