The Effects of Certain Cultural Treatments on Seed Production of Red Clover, Trifolium pratense, L.

Citation preview

PURDUE UNIVERSITY

THIS IS TO CERTIFY THAT THE THESIS PREPARED UNDER MY SUPERVISION

by

Earl Harold Collister

e n title d

The Effects of Certain Cultural Treatments on

Seed Production of Red Clover, Trifolium Pretense L.

COMPLIES WITH THE UNIVERSITY REGULATIONS ON GRADUATION THESES

AND IS APPROVED BY ME AS FULFILLING THIS PART OF THE REQUIREMENTS

FOR THE DEGREE OF

Doctor of Philosophy

Professor

H

April 4»

eap of

in

Charge

Sc h o o l

is 50

TO THE LIBRARIAN:—

aer THIS THESIS IS NOT TO BE REGARDED AS CONFIDENTIAL,

GRAD. SCHOOL FORM 9—8-49— 1M

or

D

of

T hesis

epartment

THE EFFECTS OF CERTAIN CULTURAL TREATMENTS ON SEED PRODUCTION OF RED CLOVER, TRIFOLIUM PRATENSE L. A Thesis Submitted to the Faculty of Purdue University by Earl Harold Collister In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy June, 1950

ProQuest Number: 27714151

All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is d e p e n d e n t upon the quality of the copy subm itted. In the unlikely e v e n t that the a u thor did not send a c o m p le te m anuscript and there are missing pages, these will be noted. Also, if m aterial had to be rem oved, a n o te will ind ica te the deletion.

uest ProQuest 27714151 Published by ProQuest LLC (2019). C opyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States C o d e M icroform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106 - 1346

ACKNOWLEDGEMENTS To Dr. K. T. Payne and Dr. H. H. Kramer for their encouragement, invaluable assistance, and constructive criticism, this writer wishes to express his sincere thanks. Appreciation is extended to Dr. A. J. Ohlrogge, Dr. R« L. Davis, Mr. W. B. Wilder, and Mr. R. T. Everly for

their invaluableassistance

and suggestions in conductingthis study. Thanks are also extended to the American Seed Trade Association whose funds made this investigation possible. To my wife, for her sacrifices, assistance and inspiration the author shall ever be grateful.

ABSTRACT 1 Collister, E. H., The Effects of Certain Cultural Treatments on Seed Production of Red Clover, Trifolium Pratense L. An experiment was conducted during 1947 and 1948 at the Purdue University Soils and Crops Farm located just east of Lafayette, Indiana to determine the effect of methods and rates of seeding clover alone and with oat companion crops, and insecticide treatments on seed production of red clover • Another investigation was conducted during 1949 at seven farms in northern Indiana to determine the influence of kinds and combin­ ations, rates, and time of application of commercial fertilizers upon seed production of red clover. Methods and rates of seeding red clover alone and with an oat compan­ ion crop did not signifleantly affect the seed production of the clover. Red Clover drilled at the same rate per acre in rows spaced 7 inches apart gave a slightly higher seed yield than clover drilled in rows spaced 14 inches, while both methods were superior to broadcast.

Red clover

drilled at the same rate in rows spaced 7 inches apart also was associated with other stands and forage yields than clover drilled in rows spaced 14 inches or broadcast*

Environmental conditions were probably optimum for

red clover plants growing in rows spaced 7 inches apart. Seed yield and stands of red clover increased with increased rates of seeding at 4, 8, 12, and 16 pounds per acre.

Red clover planted at the low

rate of seeding bloomed earlier and maintained more relative bloom than any of the higher rates of seeding, i.e., bloom in relation to the number of plants.

A greater total bloom at the higher rates of seeding was probably

responsible for the increase in seed yield. Red clover grown in association with either of two oat varieties during

the second, growing season than when grown alone.

Oats growing in assoc­

iation with red. clover probably removed enough nitrogen from the soil during the first growing season to limit the formation of proteins and permit formation of relatively large amounts of carbohydrates that were stored in the roots of the clover plants, thereby creating a high carbohydrate-nitrogen ratio which was conducive to abundant seed production dur­ ing the second growing season. Pre-bloom spray applications of 2 pounds of 50 per cent wettable DDT powder (l,1-bis(p-chlorophenyl) - 2, 2, 2-trichloroethane) per acre, 1 pound of toxaphene (chlorinated camphene with empirical formula Cj q

Gig with

chlorine content of 67-69 per cent) per acre, and one-half pound of 6 per cent gamma isomer of benzene hexachloride (1, 2, 3, 4, 5, 6 - hexachlorocyclohexane) per acre did not significantly affect the seed yield of red clover.

Untreated plots produced as much clover seed as treated plots.

Top dressings of nitrogen, phosphorus, potassium, magnesium, and boron applied alone and together in the spring to second-year stands of red clover significantly affected the seed yield at four of seven experimental locations. Applications of 100 and 300 pounds of phosphorus per acre to soil al­ ready medium to high in available phosphorus increased the forage yield of red clover, and consistently decreased the number of clover heads, seed yield, and seed weight.

The increased applications of phosphorus probably

resulted in an excess of phosphorus in the clover plant due to "luxury ab­ sorption" . This excess of phosphorus in the clover plant probably caused a condition of physiological imbalance which decreased growth and the production of clover heads. Potassium, applied at 50 and 150 pounds per acre to soil already high in exchangeable potassium increased the forage yield of red clover slightly.

iii but had little influence upon the number of heads, seed yield, or seed weight •

In some cases, increased applications of potassium decreased the

number of heads and seed yield of red clover, especially with the 150 pound application.

An excessive amount of potassium in proportion to the

supplies of other required nutrients in the soil probably limited the pro­ duction of clover heads by creating a condition of physiological imbalance in the plant. Phosphorus and potassium, applied together in different combinations slightly increased the forage yield and seed weight of red clover, but de­ creased the number of heads and the seed weight.

The effect cf either

fertilizer on the forage yield, number of heads, seed yield, and seed weight cf red clover was not so great when applied in combination as alone.

The

proportion of available phosphorus to exchangeable potassium in the soil was probably nearer to the optimum, for maximum growth and seed production when applied together than alone# Nitrogen applied in the spring or immediately after the forage harvest in the summerat 40 and 120 pounds per acre to

soil already high in organic

matter consistently decreased the number of heads, seed yield, and seed weight of red clover#

Increased applications of nitrogen slightly increased

the forage yield of red clover#

There was very little difference between the

spring and summer applications of nitrogen with respect to forage yield, number of heads, seed yield, and seed weight of red clover.

The increased

applications of nitrogen probably created a low carbohydrate-nitrogen ratio in the clover

plant which was not conducive toreproduction.

An application of 100 pounds of magnesium to soil already high in ex­ changeable magnesium usually decreased the forage yield, number of heads, seed yield, and seed weight of red clover.

An excessive amount of magnesium

in proportion to the sypplies of other required nutrients in the soil prob­ ably limited growth and seed production by creating a condition of physiolog­ ical imbalance in the red clover plant# An application of 25 pounds of borax per acre to soil which was probably already high in boron slightly decreased the forage yield, number of heads, seed yield, and seed weight of red clover#

An excessive amount of boron in

the soil probably decreased growth and seed production by toxic action, es­ pecially since ohly very small amounts are required for normal growth and metabolism#

TABLE OF CONTENTS Page ABSTRACT ..................................................... i INTRODUCTION................................... Purpose of the S t u d y ......................... REVIEW OF LITERATURE.......................... Effect of Methods and Rates of Seeding Legumes Alone and With Oat Companion Crops on Seed Production ......... Effect of Insecticide Treatments on Seed Production

4

......

Effect of Kinds and Combinations, Rates, and Time of Appli­ cation of Fertilizers on Seed Production........

Ô

10

EXPERIMENTAL PROCEDURE....................................

1?

Methods and Rates cf Seeding Clover Alone and With Oat Companion Crops ......

17

Insecticide Treatments ................

19

..............

19

Fertilizer Treatments

Soils U s e d ................. ........ ..... Application of Fertilizers

............

...........

Field Methods and Harvesting Techniques Laboratory Methods EXPERIMENTAL RESULTS

24 ......

........ *..........

28

The Effect of Methods and Rates of Seeding Clover Alone and With Oat Companion Crops on Seed Production of Red Clover Bloom Ratings Relative to the 1947 Forage Harvest.......

Stand of Clover

28 28

................

3

......

34

Bloom Ratings Relative to the 194# Forage Harvest 1948 Forage Yield of Clover

25 26

......

1947 Forage Yield of Clover

20

......

................

Bloom Ratings Relative to Seed Yield .....................

37 41 42

Seed Yield of Clover

Page 42

..........

The Effect of Insecticide Treatments on Seed Production of Red Clover.......... ........ .....................

48

The Effect of Kinds and Combinations, Rates, and Time of Application of Fertilizers on Seed Production of Red Clover .....

50

Effect of Fertilizationon the Forage Yield

.........

50

Phosphorus and Potassium......

50

Nitrogen............

51

Magnesium and B o r o n .........

52

Effect of Fertilization on the Production of Glover ............. Heads Phosphorus and Potassium

55

.....

55

Nitrogen................

57

Magnesium and B oron................

58

Effect of Fertilization on the Seed Yield ....... Phosphorus and Potassium Nitrogen

60

.....

60

...........

61

Magnesium and B o r o n

•••

62

Effect of Fertilization on Seed Weight «................

63

Phosphorus and Potassium.........................

63

Nitrogen................

63

Magnesium and Bar o n .........

.

DISCUSSION AND CONCLUSIONS.............................. Methods and Rates cf Seeding Clover Alone and With Oat Companion Crops .................. *..... Methods of Seeding Clover

66 68 68

......

68

Rates of Seeding Clover..................

70

Companion Crops ..............

72

/

Insecticide Treatments

......

76

Fertilizer Treatments

........

Page 78

Phosphorus

............................

78

Potassium

......

81

Nitrogen......................

84

Magnesium.

86

B or o n

..... .....

.

• 87

SUMMARY OF RESULTS ...............

89

APPENDIX.......................................

92

BIBLIOGRAPHY AND CITED REFERENCES .............................. 98

List of Tables Table 1

. Bloom Rating

on August 4, 1947 as Influenced by Methods and Rates of Seeding Red Clover Alone and With Oat Companion Crops .......

29

. Bloom Rating

2

3

Page

on August 11, 1947 as Influenced by Methods and Rates of Seeding Red Clover Alone and With Oat ...... Companion Crops ......

30

Rating on August 28, 1947 as Influenced by Methods . Bloom and Rates of Seeding Red Clover Alone and With Oat Companion Crops ........

4.

5.

6* 7.

«....

31

F Values for Methods and Rates of Seeding Clover, Oat Companion Crops, and Replications with 2/l6, 3/54» 2/l6, ..... and 2/16 Degrees of Freedom,respectively

32

The Effect of Methods and Rates of Seeding Clover Alone and With Oat Companion Crops on the Forage Yield of Red Clover, September 2, 1947 ..............

34

Correlation Coefficients for the Relationship between Forage, Stand, Bloom, and Seed Data ofRed Clover .....

35

Total, Partial, and Multiple Correlation Coefficients for the Relationship between Stand, Forage, and Seed Data of Red Clover... ............

35

. Stand Rating of Red Clover on October 20, 1947 as Affected by Methods and Rates of Seeding Clover Alone and With

8

Oat Companion Crops 9.

10

.

.

11

12.

......

36

Stand Rating of Red Clover on April 30, 1948 as Affected by Methods and Rates of Seeding Clover Alone and With Oat Companion Crops ......................

38

Bloom Rating on June 3, 1948 as Influenced by Methods and Rates cf Seeding Red Clover Alone and With Oat Com­ panion Crops .....

39

Bloom Rating on June 8, 1948 as Influenced by Methods and Rates of Seeding Red Clover Alone and With Oat Companion Crops .......

40

The Effect of Methods and Rates of Seeding Clover Alone and With Oat Companion Crops on the Forage Yield of Red Clover, June8, 1948 ..........

43

13.

14®

15.

16.

17. 18.

Bloom. Hating on June 30, 1948 as Influenced by Methods and Rates of Seeding Red Clover Alone and With Oat Com­ panion Crops ...........

44

Bloom Rating on July 13, 1948 as Influenced by Methods and Rates of Seeding Red Clover Alone and With Oat Com­ panion Crops .........

45

Bloom Rqting on July 20, 1948 as Influenced by Methods and Rates of Seeding Red Clover Alone and With Oat Com­ panion Crops .... .. . . ....

46

The Effect of Methods and Rates of Seeding Clover Alone and With Oat Companion Crops on the Seed Yield of Red Clover, August 28, 1948 ..........

47

The Effect cf Insecticide Treatments on the Seed Yield of Red Clover ....................

49

The Influence of Phosphorus and Potassium Fertilization upon .... the Forage Yield of Red Clover

52

19a. F Values for Forage and Seed Yields with 14/42 and 3/42 Degrees of Freedom for Treatments and Replications, respe ctively.....

53

19b. F Values for Head Count and Weight per 100 Seeds with 14/42 and 3/42 Degrees of Freedom for Treatments and Replications, respectively ............... .

53

20. The Influence of Nitrogen Fertilization upon the Forage Yield of Red Clover..........

54

21. The Influence cf Magnesium and Boron Fertilization upon the Forage Yield of Red Clover .......

54

22. The Influence of Phosphorus and Potassium Fertilization upon the Production of Clover Hea d s

57

23. Correlation Coefficients for Forage, Seed, Head Count, and .... Seed Weight Data of Fertilizer Treatments

58

24. The Influence of Rate and Time of Application of Nitrogen upon the Production of Clover Heads .......................

59

25. The Influence of Magnesium and Boron Fertilization upon the Production of Clover Heads ..........................

59

26. The Influence of Phosphorus and Potassium Fertilization upon the Seed Yield of Clover *..............

64

27. The Influence cf Rate and Time of Application of Nitrogen Fertilization upon the Seed Yield of Clover ...............

65

Table 28. 29.

Page The Influence of Magnesium and Boron Fertilization upon the Seed Yield of Clover........

* 65

The Influence of Phosphorus and Potassium Fertilization upon the Seed Weigjht of Clover ........

66

The Influence of Rate and Time of Application cf Nitrogen Fertilization upon the Seed Weight of Clover ...........

67

The Influence of Magnesium and Boron Fertilization upon the Seed Wei^at of Clover ...... .. .... ......

67

32*

The Effect of Methods cf Seeding Clover on Seed Production ...

68

33*

The Effect of Rates of Seeding Clover on Seed Production

71

34»

The Effect of Companion Crops on Seed Production of Red Clover

30. 31*

35* 36. 37. 38.

....

The Effect of Insecticide Treatmait on the Seed Yield cf Red Clover...........

77

The Influence cf Phosphorus Fertilisation upon Factors Affecting Seed Production of Red Clover ....

78

The Influence of Potassium Fertilization upon Factors Affect­ ing Seed Production of Red Clover ...............

81

The Influence cf Phosphorus and Potassium Fertilization upon Factors Affecting Seed Production of Red Clover .....

83

39 * The Influence of Rate and Time of Application of Nitrogen Fertilization upon Factors Affecting Seed Production of Red Clover .... 40. 41.

72

85

The Influence of Magnesium Fertilization upon Factors Affect­ ing Seed Production of Red Clover (......

86

The Influence of Boron Fertilization upon Factors Affecting Seed Productionof Red Clover

88

Tables in Appendix I.

Chemical Analyses of Surface Soil at Seven Experimental Loca­ tions in Northern Indiana »

92

II* Chemical Analyses cf Subsoil at Seven Experimental Locations in Northsm Indiana .................

92

III. Effect of Methods and Rates of Seeding Clover, Oat Companion Crops, and Insecticide Treatments on Seed Production of Red Clover .....

93

Table

Page

IV. Analysis of Variance for Methods and Rates cf Seeding Clover, Oat Companion Crops, and Insecticide Treatments on Seed Product ion cf Red Clover.... ....... V.

Analysis of Variance for the Effect of Methods and Rates of Seeding Clover Alone and With Oat Companion Crops on the Stands and Forage Yields of Red Clover......

94

95

VI. Analysis of Variance for the Effect of Methods and Rates cf Seeding Clover, and Oat Companion Crops on the Bloom of Red Clover ...........

96

VII. Analysis of Variance for the Effect of Methods and Rates of Seeding Clover, and Oat Companion Crops on the Bloom of Red Clover ..........

97

THE EFFECTS OF CERTAIN CULTURAL TREATMENTS ON SEED PRODUCTION OF RED CLOVER, TRIFOLIUM PRATENSE L.

INTRODUCTION Red clover is commonly regarded as one of the most important and most widely known of all cultivated legumes.

For centuries it has been regarded

as a corner stone of a permanent system of agriculture in the Old World, while in this country it has been a leading factor in crop rotation practices which were designed to conserve productivity of the soil.

Thus, the impor­

tant part which red clover has played in maintaining a profitable world agriculture can not be overstated. One of the most serious problems confronting the American farmer in many of the clover sections is the increasing difficulty of successfully es­ tablishing and maintaining stands of red clover which are conducive to high forage and seed yields.

The increasing difficulty of producing red clover

seed has become a problem of major importance during recent years. Low seed yields have been largely responsible for a decline in popularity of red clover among farmers and agricultural workers.

For instance, during the

period 1936-45 the average acreage of red clover harvested for seed in Indiana was 217,700, while acreage harvested for the years 1946, 1947, 1948, and 1949 was 420,000, 126,000, 232,000, and 93,000, respectively (74) *1/

In addition,

the yield per acre has gradually declined from an average of 0.82 bushel dur­ ing the period 1936-45 to 0.70, 0.65, and 0.65 for the years 1946, 1947, 1948, and 1949, respectively, and Indiana now ranks very low with respect to yield of red clover seed per acre. Generally speaking, seed production of red clover has been sufficient 1/ Numbers in parenthesis refer to Bibliography.

2 in most years to meet the needs of farmers in this country with some sur­ plus*

However, seed yields per acre in the region where red clover is most

extensively grown have been relatively low, even in years when environment has favored seed production*

Consequently, the market has had to operate

from year to year on a fluctuating supply of red clover seed with prices de­ pending upon scarcity or abundance of supply*

Therefore, it is extremely

important that cultural methods be developed which would serve to remove much of the uncertainty attached to seed production.

Such methods should help to

overcome the delays usually encountered in the distribution of seed of new strains• Cultural practices employed in securing high seed yields have been quite variable among farmers and agricultural workers*

Consequently, much uncer­

tainty and confusion has been attached to the product ion of seed*

For exam­

ple, in the Middle West it is a common practice to use oats as a companion crop when establishing red clover seedings.

Yet, relatively high seed yields

of red clover are frequently obtained when it is seeded without a companion crop*

It is desirable, therefore, that the effect of oats on the subsequent

red clover seed crop be better understood and also that other cultural practices which will, be beneficial from the standpoint of the clover crop be determined*

It is believed that methods and rates of seeding clover alone

and in combination with an oat companion crop may have a pronounced effect on the subsequent seed yield of red clover*

It is also conceivable that in­

jurious clover insects such as leafhoppers and grasshoppers, may materially affect seed production of red clover*

The effect of application of kinds,

combinations, and rates of fertilizers may also be a contributing factor in seed production cf red clover, since variable seed yields commonly occur under diverse soil condition*

3 A knowledge of the interrelationships of these factors and their relative importance is fundamental to the adoption of the most favorable cultural practices*

For this reason an intensive study of these various

factors was undertaken in the spring of 1947* Purpose of the Study With these viewpoints in mind, experiments were designed to determine the following : (l) whether methods and rates cf seeding red clover alone and in combination with two different oat companion crops materially affect the seed yield of red clover, (2) whether application of insecticides in­ fluences the seed yield of red clover, and (3) whether different kinds and combinations, rates, and time of application of fertilizers exhibit any measurable influence on seed production of red clover.

4 REVIEW OF LITERATURE Early investigations concerning the most desirable cultural practices of producing red clover seed were rather limited.

Little actual data were

recorded and analyzed, but extensive observations were made.

Investigations

with alfalfa and other legumes were quite extensive, but very little work was done with red clover.

Consequently, it has been necessary to depend

upon such investigations with other legumes as a source of information per­ tinent to red clover. Effect of Methods and Rates of Seeding Legumes Alone and With Oat Companion Crops on Seed Production In 1908, Moore and Delwiche (51) conducted an experiment to determine the relative value of medium red clover when sown with and without an oat companion crop.

On May 9* one-half of each experimental plot seeded with

red clover was sown with a companion crop and the other half without.

On

June 24, they noted that there was a better development of the clover plants on the plots where no companion crop was sown than on the other plots. Where no companion crop was used the clover looked much better and the stand was much thicker than where the companion crop was grown in association with the clover.

They observed that the clover growing with oâts suffered

severely during any period of drought.

From these observations, they con­

cluded that it would be better to sow the clover without a companion crop when soil moisture was a limiting factor in plant growth.

They also be­

lieved that 8 to 15 pounds of clover seed per acre was essential for a good stand.

However, no actual data were presented to substantiate either of

these recommendations. Pieters (55) stated that it was necessary to remeaber that the oat companion crop always has an advantage over the clover, since it is a more

5 rapidly growing crop, and that on soils where fertility or moisture is not abundant the weaker plants must suffer.

He believed that the presence of

a companion crop on poor or droughty soil was always a source of danger to the clover, and that many clover failures were probably due to the compe­ tition of the oat crop* In 1933, Virtanen (76) conducted an investigation on the optimum oat/ legume ratio. Results from both pot and field experiments showed that one pea plant was capable of supply sufficient nitrogen for the growth of two oat plants, provided that the acidity of the soil was not higher than pH 6.0 and that the soil either contained vigorous strains of nodule bacteria or that the seed was inoculated.

He noted that the growth of the oats was

markedly impaired as soon as the ratio oats/peas exceeded two.

The growth

of the pea was also weakened, probably owing to a deficiency in nitrogen. It is regretable that no seed data were taken when

this legume wasgrown in

association with the oat companion crop. Madhok (45) conducted a similar sand culture experiment with wheat and chick-peas.

He recorded the average height of the plant top, number of seeds

per plant and total weight of the crop on an oven-dry basis.

The results

showed that chick-peas suffered in plant growth as well as in nitrogen con­ tent by their association with wheat; whereas, the wheat seemed to have benefited slightly.

The percentage of nitrogen found in wheat, wheat plus

chick-pea, and chick-pea was 0.55> 0.67, 1.43; and 1.52, respectively*

The

average number of seeds per plant for wheat, wheat

plus chick-pea, and chick­

pea was 2.7; 2.1, 2.0; and 3.0, respectively.

data indicated that a

His

single chick-pea plant could supply enough nitrogen to support as many as four wheat plants.

However, the chick-peas lost 35 to 40 per cent in size

of tops and 14 to 19 per cent in weight by their association with wheat*

6 Madhok also measured the amount of nitrogen excreted from the roots of the chick-peas • The amount of nitrogen excreted was greater when the legume was grown alone than when it was grown in association with a nonlegume . This was probably due to the fact that the wheat plant took up the excreted nitrogen, Albrecht (l) conducted investigations with vetch when grown with the companion crops rye, wheat, oats, and barley.

Results from small plot tests

indicated that seed production of vetch was greatly increased when grown with a companion crop. As early as 1920, Blinn (7) reported data from studies made in Colorado which indicated that thin stands of alfalfa generally produced higher seed yields than heavy stands, He observed that in thick stands, limited to the tips of the stems, while a thin stand exposed a larger proportion of the plant to light and air, which permitted a greater amount cf bloom on the scattered branches.

He reasoned that the greater amount of bloom on the

thin stand enabled a heavier seed yield to be produced, assuming that all other growth conditions were favorable • Blinn also studied the effect of spacing on the seed yield of alfalfa by planting it in rows spaced at different distances.

He noted that a thin stand was necessary but lack of

space was not the general cause of failure to produce seed.

He was able

to secure unifora, thin stands by seeding in rows 6 to 8 inches apart at 1 to 3 pounds per acre, Carlson (10) studied the effects of different rates of seeding alfalfa and row spacings on the seed yield of alfalfa. rate of 2,

He seeded alfalfa at the

and 9 pounds per acre in rows spaced 21, 28, and 42 inches.

Forage yield data showed that the rate of seeding and the thickness of stand did not influence the amount of vegetative growth, provided weed

7 grovrfch was controlled*

However, the seeding of 9 pounds per acre did pro­

duce hay of finer quality than the 4 or 2 pound seeding*

Results from four

seed crops showed that the different rates of seeding did not produce sig­ nificant differences in seed yield*

Similar results were obtained for the

various row spacings. Wilsie (82) conducted a rather extensive plant-spacing study with legumes in Hawaii.

He grew pigeon peas in rows spaced 5 feet apart in which

hills were spaced 2g,

and 7g feet, respectively.

per hill varied from one to four.

The number of plants

His seed results indicated that the 5

by 7è foot spacing was slightly superior though the statistical analysis showed this difference to be non-significant.

It was also found that there

was very little difference in yield whether there were one or four plants per hill. Tysdal (73) investigated the effect of plant spacing on seed production of alfalfa.

He spaced alfalfa plants 8, 32, and 64 inches apart.

The high­

est forage production was obtained with the close spacing of 8 inches; how­ ever, the very wide spacings usually averaged higher in seed production. Mercer (49) recommended low rates of seeding alfalfa for high seed production, since he found that large individual plants produced more seed than several small plants* The effect of rate of planting red clover on the yield of forage was investigated by HolloweH and Heusinkveld (31) ♦ Red clover was planted at the rates of 5, 10, 15, and 20 pounds per acre in rows 4 inches apart. The data showed that the 5 lbs. rate produces a forage yield significantly lower than the higher seeding rates.

No significant differences were found be­

tween the 10, 15, and 20 pound rates however.

They believed that the 5

pound rate of seeding did not provide sufficient plants for maximum yields.

8 Harper (27) determined the effect of spacing sweet clover in rows 7 and 42 inches apart on the yield of forage. The yield of top growth in the 7 inch rows was much greater than it was in the 42 inch rows. Albrecht (l) recommended seeding 10 to 15 pounds of vetch per acre for high seed production.

His experimental results showed that drilling

vetch 7.5, 10, and 20 pounds per acre produced 133, 184, and 145 pounds of seed per acre, respectively.

Broadcasting at these same rates produced 2,

22, and 0 pounds of seed per acre, respectively. Effect of Insecticide Treatments on Seed Production The importance of controlling deleterious clover insects was realized by Gossard (24) as early as 1915*

He noted that the clover leaf weevil

(Hypera punctatus Fabricius) caused considerable damage to the leaves of red clover every spring.

The larvae fed during mild days in winter and soon

after the leaves unfolded in late March or early April, resulting in a large reduction in forage yield.

Arsenical sprays applied in late fall or

early spring were effective in controlling the clover leaf weevil.

The less

adhesive and more quick-acting arsenicale such as Paris green and arsenite of soda were found to be best suited for use in the spring. Jewett (34) noted that the potato leafhopper (Empoasca fabae Harris) caused considerable injury to clover and alfalfa.

He conducted controlled

tests to determine the extent of injury to red clover plants.

It was found

that the infested clover plants made much less growth than those not infest­ ed with leafhoppers. unifested plants.

The infested plants were weaker and shorter than the

Injury to the plant was manifested by wilting of the

leaves and tips of stems, discoloring of the leaves, and sometimes dwarfing of the plant.

9 Treatment m t h Insecticides was suggested as a possible means of control. Schwardt, Newsom, and Norton (64) attempted to determine the extent of insect injury to red clover in New York.

They used 1, 2, and 3 per cent

DDT 5/dust at 50 pounds per acre and 1, 2, and 3 per cent benzene hexa­ chloride 2/at 50 pounds per acre.

All insecticides were applied at weekly

intervals during May and the first week in June.

The greatest increases in

yield of clover hay were obtained from the plots dusted with 1 or 2 per cent material.

Significant increases in yield were obtained for all treated

plots over the untreated plots. Benzene hexachloride (1%) increased the forage yield 22 per cent over the untreated plots ; whereas, DDT dust (l%) increased the yield 16 per cent. Wilson (85) initiated a study during the summer of 1946 to determine the effect of insect control on alfalfa seed production.

Insecticidal spray

treatments were applied on July 12, in the pre-bloom stage. His data in­ dicated that the application of 2 pounds of DDT per acre increased the seed yield of alfalfa 85 per cent; whereas, 1 pound of DDT plus 8 ounces of chlordan per acre increased the seed yield 102 per cent.

Parathion applied

at the rate of 8 ounces per acre increased the seed yield 79 per cent* Chlordan applied at 1 pound per acre decreased the seed yield by 25 per cent. Davis and Wilson (17) initiated experiments during 1949 to test the efficacy of some organic insecticides in controlling alfalfa insects.

Their

results showed that 2 pounds of DDT emulsion per acre applied on July 11 did not significantly increase the seed yield of alfalfa.

However, 2 pounds

of 50 per cent DDT wettable powder per acre did increase the seed yield to

2/ 1, 1-bis (p-chlorophenyl) - 2, 2, 2 — trichloroethane 2/ 1, 2, 3, 4, 5, 6 - hexachlorocyclohexane

10 more than twice that of the untreated plots*

Toxaphene 4/applied at the

rate of 2 pounds per acre did not increase the seed yield of alfalfa# Wüsie (83) conducted extensive field experiments in an effort to increase alfalfa and red clover seed production by controlling destructive insects#

Applications of 1 and 2 pounds of DDT per acre in the pre-bloom

stage resulted in marked increases of from 400 to 500 per cent in the seed yield of alfalfa#

However, the same treatment did not produce significant

increases in the seed yield of red clover# Effect of Kinds and Combinations, Bates, and Time of Application of Fertilizers on Seed Production It has been found that magnesium or potassium may exert an influence upon the absorption of phosphorus and nitrogen by plants#

Truog et al. (72)

conducted investigations with peas under field conditions and in nutrient culture#

The quantities of phosphorus and magnesium were varied in the soil

and nutrient solution#

Chemical analyses of the pea seeds showed that a

consistent increase in the phosphorus content of the peas accompanied an increased supply of available magnesium in the nutrient solution#

In add­

ition, the phosphorus concentration was increased more by the addition of magnesium than by the addition of phosphorus itself* Knowles et al» (38) found that potassium fertilization significantly lowered the nitrogen and phosphorus concentration of the potato#

Results

from their field experiment showed that the phosphorus and nitrogen contents of all parts of the plant from the nitrogen-phosphorus-potassium treated plots were much lower than those from the nitrogen-phosphorus treated plots* Lucas et al. (44) grew plants on different fertility levels and con—

/j/ Chlorinated camphene with empirical formula C^q h10 Gig with chlorine content of 67 to 69 per cent

11 eluded that a reciprocal relationship of magnesium and calcium to po­ tassium. content existed.

Their work with legumes showed that the sum of

the milliequivalents of these three cations tended to remain constant. The total cation sum remained fairly constant when there were wide varia­ tions in the individual cations. Studies concerning the abilities of the cations to replace each other in plant absorption were made by Van Itallie (75)#

He saturated the soil

complex with various ratios of cations and determined the amounts of cations absorbed, which gave an indication of the "competitive ability11 of the four cations found most abundantly in plants.

He ranked these four cations in

the following order; potassium, sodium, magnesium, and calcium.

In accord­

ance with this finding, the absorption of potassium would be greatly in­ fluenced by its concentration in the soil, to a lesser degree by sodium, while magnesium and calcium soil concentrations would exert very little in­ fluence upon potassium absorption.

The absorption of magnesium would be

influenced markedly by magnesium and potassium, less by sodium and little by calcium concentration in the soil.

Thus, the ratio of calcium to potass­

ium, sodium, and magnesium in the soil would be expected to influence the absorption of calcium. The work of Carolus (ll) is in support of the research of Van Itallie. His results showed that the addition of potassium to a medium composed of one-half washed sand and one-half soil stimulated potassium absorption by bean plants.

Potassium produced such a dominant effect on its absorption

that calcium, magnesium, and sodium had no influence on potassium absorp­ tion.

However, potassium did have a depressing effect upon calcium and mag­

nesium absorption. Prince et al. (60) have stated that the quantity of potassium available

12 to the plant is the most important single factor which influences the absorption of magnesium.

They found that the absorption of magnesium was

low when there was an abundant supply of potassium in the soil. Sommer, Wear, and Baxter (68) studied the effect of magnesium, fertili­ zation on certain crops in Alabama.

They noted that clover gave an increase

in forage growth with the addition of magnesium.

However, certain soils

failed to give any response to magnesium fertilization. Investigations concerning the response of plants to magnesium fertili­ zation were also conducted by Prince et al. (60).

They found that crops

would respond markedly to applications of magnesium, if magnesium originally occupied less than 6 per cent of the exchange complex of the soil.

They

believed that the ideal situation would be for magnesium to occupy 10 per cent of the total exchange capacity of the soil. Mann (46) conducted greenhouse experiments with red clover in an effort to ascertain the effect of mineral manures, potassium nitrate, and large quantities of farmyard manure on clover plant growth.

He treated some pots

with the equivalent of 4*4 tons of calcium carbonate, 175 pounds of phos­ phoric acid, and 120 pounds of potash per acre.

This treatment did not

produce any increase in growth over the untreated pots. pounds of nitrogen per acre was also without effect.

Application of 244

However, an application

of 135 grams of dried farmyard manure, containing 2.22 per cent nitrogen, stimulated growth considerably.

The weight per plant in the treated and un­

treated pots was 11.6 and 0.9 grams, respectively. Albrecht et al. (3) studied the effect of fertilizers on sweet clover in a four-year rotation of corn, oats, wheat, and sweet clover.

The ferti­

lizer treatments consisted of applying 475 pounds of superphosphate per ro­ tation, and 475 pounds of potash; 2 tons of limestone every 8 years.

They

13 calculated forage yields of entire plant, roots, tops, and root/top ratio under all treatments,

A complete chemical analysis was conducted for each

of these plant parts.

They found that the potash along with the calcium

and phosphorus had the most outstanding effect, not only in making more plant bulk, but also in making for more total nitrogai in the plant per acre of tops and per acre of roots.

Potash was also the major factor re­

sponsible for a larger concentration of nitrogen in the tops, while there was a lower concentration in the roots. The effect of nitrogen, phosphorus, potassium, manure, and limestone on the production of field crops was studied by Wright et al, (&7),

The

application of 175 pounds of nitrogen and 100 pounds of potash per acre had little effect on the forage yield of red clover grown in a 4-year crop ro­ tation,

However, the application of 400 pounds of superphosphate per acre

significantly increased the yield of clover. Investigations by Snider (66) in Illinois showed that red clover re­ sponded rather remarkably to potash treatment on land deficient in available potassium.

The application of 400 pounds of muriate of potash to wheat

definitely increased the forage yield of clover, even on soils which were al­ ready relatively high in available potassium, Ladygin (42) obtained the highest forage yields of red clover when it was top dressed with phosphorus and potassium in the spring, Kelley (37) attacked the problem of nitrogen fertilization in respect to legumes.

His results indicated that under certain practical farm con­

ditions, the application of commercial nitrogen might markedly stimulate the growth of legumes, particularly during the seedling stages, Poehlman (57) concluded that when oats are used as a companion crop for clover the use of commercial fertilizer has a double effect in increas-

14 ing the grain yields and improving the stands of the legume* In 1920, Blinn (7) postulated that increased soil nitrate was respon­ sible for decreased seed yields of alfalfa, since alfalfa grown on plots high in nitrates failed to bloom normally* Westgate (78) stated that too much nitrogen in the soil induced an outgrowth of stems and leaves at the expense of the seed crop*

He believed

that soils of medium fertility were desirable for producing large seed yields with crimson clover*

More fertile soils were recommended when for­

age or green manure crops were the main objective. The effect of boron on forage yields of alfalfa was studied by Dawson and Gustafson (16) in New York*

They conducted several hundred field tests

and found that borax applications did not increase alfalfa yields, although boron deficiency symptoms were observed in 17 per cent of the tests* Dmitriev (20) conducted an investigation in Russia and noted that applications of borax to red clover increased the number of flowering heads and seed yield.

Mass flowering began earlier on the borax treated plots*

The effect of boron on the forage yield was far less noticeable • In tests by Grizzard et al, (26) in New Jersey borax applied at the rate of 35 pounds per acre resulted in an increase in forage yield of alfalfa from 289 to 743 pounds per acre*

The seed yield on plots treated with borax

ranged from 82 to 184 pounds ; whereas the plants on the plots receiving no borax failed to set any seed* Hutcheson and Cocke (32) obtained remarkable results in Virginia by treating alfalfa with borax.

When 10 pounds of borax was applied as a top

dressing before growth started in the spring, there was an increased forage yield of 4517 pounds per acre*

Applications of borax also resulted in the

yield of some seed where none was obtained from, the untreated plots.

Sim-

15 liar results were obtained by Midgley (50) in Vermont. Naftel (53) conducted greenhouse cultural experiments to determine the effect of various rates of boron at various levels of liming on plant growth and seed yield of crimson clover.

Where boron was added in concen­

trations from 0 to 1.5 p.p.m to soils at various levels of liming, 0.3 p.p.m. boron were most effective in the development of seed heads and in total plant yields. Similar results were obtained by Piland et al. (56) in North Carolina. The use of boron increased the forage yield of alfalfa as much as 29 per cent. The average seed yield for check plots was 19.1 pounds per acre, while the addition of 0.5, 1.0, and 1.5 p.p.m boron produced an average of 460, 433, and 529 per cent increase, respectively.

Applications of 0 and 15 pounds of

borax per acre to crimson clover produced an average of 270.5 and 390.5 pounds of seed per acre, respectively.

This increase of 120 pounds of seed

per acre was significant. Similar increases in seed yield of crimson clover were obtained by Rogers (63) in Alabama.

Applications of 20 pounds of borax per acre produced

an average increase of 259 pounds of seed per acre.

However, no increase in

plant growth was obtained where the untreated soil contained more than 0.15 p.p.m boron.

He believed that 8 to 10 pounds of borax per acre would not in­

jure any of the legumes which might need additions of borax. Dregne and Powers (19) in Oregon found that boric acid used at the rates of 20, 40, and 60 pounds per acre with red clover gave average forage in­ creases of 95, 82, and 61 per cent, respectively. Reeve and Shive (62) conducted a careful quantitative study to determine the potassium-boron and caleium-boron relationships in plant nutrition. They found that the potassium concentration of the substrate had a definite

16 influence upon the accumulation of boron in the tissues of the tomato plant*

At any given boron level in the substrate there was a progressive

increase in the boron content of the plant as the potassium concentration in the substrate increased*

Boron toxicity was noted to decrease markedly

with increased concentrations of calcium*

In this respect, the influence

of calcium was opposite to the accentuating effect of potassium, Jones and Scarseth (36) stated that each plant has a specific need for calcium and boron, and that normal growth occurs only when a certain balance in the intake of calcium and boron exists.

They found that boron could be

added in larger quantities to alkaline or limed soils than to acid soils without toxic effects.

17 EXPERIMENTAL PROCEDURE The data on red clover were taken from an experiment conducted at the Purdue University Soils and Crops Farm located just east of Lafayette, Indiana, and an investigation conducted at seven farms in northern Indiana* These experiments were designed to determine the effects of methods and rates of seeding clover alone and with oat companion crops, insecticides, and commercial fertilizers on seed production of red clover. Methods and Rates of Seeding Red Clover Alone and With Oat Companion Crops An experimentwas established at the Purdue University Soils and Crops Farm in the spring

of 1947 to test the effect of

methods and rates of seed­

ing clover alone and in combination with oat companion crops on the seed production of red clover » The field plan of this experiment was a split plot design consisting of thirty-six treatments, each replicated three times to make a total ofone-hundred and eight plots. by 16.5 feet or 1/565 acre in size*

These plots were 4*6? feet

Distance between plots was IS inches■

This investigation was conducted on a Brookston-Crosby silt loam soil, high in phosphate and potash. harrowed in the spring of 1947.

The plot area was plowed, double disked, and On May 14, 1947, Kenland red clover was

planted at the rates of 4, 8, 12, and 16 pounds per acre; broadcast or drilled in rows spaced ? and 14 inches apart ; with and without an oat com­ panion crop. and Neosho.

The oat companion crop consisted of two varieties, Benton A small seed drill was used to distribute the seed in rows,

and broadcast plots were seeded by hand.

After the clover had been seeded,

the oat companion crops were broadcast at the rate of 6 pecks per acre crosswise of the plots.

IS It was necessary to spray for leafhoppers on July 21, 1947 with 4 pounds of DDT per acre.

On July 29, the Neosho oats were cut with a hand

sickle just above the clover and removed from, the plots.

The same pro­

cedure was used in removing the Benton oats on August 6. In 1947 and 1948 estimates of bloom were taken at one week intervals two or three weeks prior to the forage or seed harvest.

This consisted of

estimating from 0 to 10 the amount of bloom of a plot in relation to the total number of plants or potential bloom of that plot, i.e., 0 represented no bloom and 10 indicated complete bloom.

For example, a plot estimated

to have one-half of its total number of plants in bloom was ranked 5; where­ as, complete bloom would be given a rating of 10.

The same method was used

for estimating the amount of stand in the fall of 1947 and spring of 1948, i.e., 0 represented no stand and 10 represented a complete stand. On September 2, 1947, and June 8, 1948, the clover plots were harvested between the one-tenth and one-half bloom stage. plots before harvesting.

Weeds were removed from all

A power driven siekle-har mower 38 inches wide was

used to cut the red clover approximately two inches from the surface of the soil.

A 12—inch strip was cut from each end of the plots as border and then

a swath the width of the mower was cut down the center of the plots.

This

gave a border at each end of 21 inches and a border of 27 inches on each side of the plot.

Each plot was cut, raked, and weighed.

Approximately 500 gram

moisture samples were obtained from each plot immediately after cutting. These were weighed and reduced to constant weight in a forced air dryer oper­ ating at approximately 160°F.

The forage yields were calculated at 12 per

cent moisture. All data were subjected to an analysis of variance, and least signifi­ cant differences were calculated when the F values were significant.

19 Correlation coefficients were also calculated* The harvesting technique employed in obtained the seed yields will be discussed under the section of insecticide treatments * Insecticide Treatments In order to determine the effect of insect control on seed production of red clover, each of the aforesaid one-hundred and eight plots was di­ vided into four subplots four feet square and sprayed with 2 pounds of 50 per cent wettable DDT 5/powder per acre, 1 pound of toxaphene A/per acre, and one-half pound 6 per cent gamma isomer of benzene hexachloride 2/per acre*

An estimate of the insect population was obtained by collecting

insects in a sweep net.

These insecticidal sprays were applied on July 6,

1946 when the clover was in the pre-bloom state, care being taken to apply the materials just prior to flowering.

The materials were applied with a

50-gallon Bean sprayer with a delivery rate of 4 gallons per minute.

Con­

trol of insecticide drift was maintained by spraying within a 4 by 4 by 2 ft. frame covered with oilcloth. A hive of honeybees was moved to the experimental plots on July 9 to help promote pollination. On August 20, 1946 each subplot was mowed and clippings were placed in a numbered burlap bag.

The seed was threshed with a mechanical clover huiler.

The seed yield data were calculated in bushels per acre* Fertilizer Treatments An investigation was begun in the spring of 1949 to measure the effect

5/ 1,1—bis (p-chlorophenyl) - 2, 2, 2 - trichloroethane 6/ chlorinated camphene with emperical formula C^q Clg with chlorine content of 67-69 per cent 7/ 1, 2, 3, 4, 5, 6 - hexachlorocyclohexane

20 of nitrogen, phosphorus, potassium, magnesium, and boron on the seed yield of red. clover*

A pseudo-factorial experiment laid out in a randomized

block design was conducted at seven farms in northern Indiana, four in Kosciusko County and three in Noble County*

This experiment consisted of

fifteen treatments, each replicated four times to make a total of sixty plots at each location*

The plots were 6 feet wide by 20 feet long, or

1/363 of an acre* Unifom stands of second-year red clover were selected during the first week of April, 1949*

Several soil types were selected in addition to vari­

ation in fertility level in an effort to obtain considerable latitude of soil conditions*

Suitable soils and stands of clover were obtained at the

Harry Vanator, Jake Widman, Ralph Spangle, Emra Stookey, Emmitt Smith, Edward Kenney, and Carl Graves farms which will be referred to as location numbers 1, 2, 3, 4, 5, 6, and 7* respectively. Two comppsite soil samples, each consisting of 20 borings 8-12 inches deep and three subsoil samples 18 inches deep, were taken at each location before fertilizer treatments were applied in the spring*

These samples were !

air-dried, ground to pass a twenty-mesh sieve and stored in pint fruit jars for chemical analyses • Soils Used

The soil at location 1 was a Fox loam which is usually a

brown loam to a depth of 6 or 8 inches. It grades downward into a somewhat heavier loam or silty loam cf light brown color*

The lower subsoil usually

varies from a reddish-brown to clay loam in which some gravel occurs. Oxidation is usually very uniform throughout the loam material* material rarely occurs within 40 inches of the surface*

Calcareous

This soil type has

good natural drainage, deep aeration, and excellent moisture-holding capaci-

21 ties.

The topography is nearly level.

The pH of the surface soil ran

about 7*2, and the average pH of the subsoil was approximately 6.7*

The

exchangeable potassium of the surface soil was ,34 m.e. per 100 grams of soil, or 318 pounds of potash per acre.

Exchangeable potassium of the sub­

soil was ,23 m.e. per 100 grams, or 216 pounds of potash per acre.

There

were .71 m.e, of magnesium per 100 grams of surface soil, and .67 m*e. mag­ nesium per 100 grams of subsoil.

There were 8.09 m.e. of calcium per 100

grams of surface soil, and 7*35 m.e. of calcium per 100 grams of subsoil. The readily available phosphorus of the surface and subsoil was 34.4 and 186.0 pounds per acre, respectively.

Total per cent nitrogen in the soil

run by the Kjeldahl method was .29, which would indicate an organic matter content of $.80 per cent, A Miami loam soil existed at location 2.

The surface soil has 6 to 8

inches of grayish-brown, friable, rather coarse-textured loam, which has a grayish cast in dry cultivated fields. This surface soil is underlain by 10 or 15 inches of pale-yellowish or light-yellowish brown loam, more silty than the surface soil.

The topography is irregularly rolling.

This soil type will

endure dry weather exceptionally well if properly tilled, since it is retent­ ive of moisture (71).

The pH of the surface soil ran about 6.6, and the

average pH of the subsoil was 6.4*

The exchangeable potassium of the surface

soil was ,36 m.e. per 100 grams, or 336 pounds of potash per acre.

Exchange­

able potassium of the subsoil was .23 m.e. per 100 grams, or 216 pounds of potash per acre.

There were .50 m.e. of magnesium per 100 grams of surface

soil, and .46 m.e. magnesium per 100 grams of subsoil.

There were 4.90 m.e.

of calcium per 100 grams of surface soil, and 6.98 m.e. per 100 grams of sub­ soil.

The readily available phosphorus of the surface and subsoil was 12.6

and 86.0 pounds per acre, respectively.

Total per cent nitrogen in the soil

22 was #17> or 3*40 per cent organic matter• The soil at location 3 was a Brookston silt loam which has a mellow silt loam surface layer.

There is usually but little sand or gravel in the

surface soil, and the silty clay loam subsoil contains no stony material except in the lower part*

This soil furnishes a good supply of moisture,

owing to the presence of a water-bearing substratum a few feet below the surface.

The topography is gently rolling (71)#

The pH of the surface soil

ran about 6,0, and the average pH of the subsoil was 6.0#

The exchangeable

potassium of the surface soil was .72 m.e. per 100 grams, or 660 pounds of potash per acre.

Exchangeable potassium of the subsoil was .31 m.e* per 100

grams, or 288 pounds of potash per acre.

There were #22 m.e. of magnesium

per 100 grams of surface soil, and .29 m.e. of magnesium per 100 grams of sub­ soil*

There were 1*35 m.e. of calcium per 100 grams of surface soil, and 2.11

m.e. per 100 grams of subsoil.

The readily available phosphorus of the sur­

face and subsoil was 39.4 and 180.0 pounds per acre, respectively.

Total per

cent nitrogen in the soilwas .13, or 2.60 per cent organic matter* Experimental plots at location 4 were situated on Warsaw loam.

The sur­

face soil is a dark-brown to brownish-black, friable loam in which there is usually a little coarse sand and some gravel.

At depths of 8 or 10 inches

it grades into a chocolate-brown loam which becomes very sandy. subsoil is a reddish-brown gravelly sandy loam. known as 11the prairie”.

The lower

This soil type is locally

It has excellent productive capacities. Leaching

and oxidation are rather active, owing to the gravelly substratum (71) • The pH of the surface soil ran about 6.3, and the average pH of the subsoil was 5.5

The exchangeable potassium of the surface soil was .29 m.e. per 100

grams, or 276 pounds of potash per acre.

Exchangeable potassium of the sub­

soil was .19 m.e. per 100 grams of soil, or 144 pounds of potash per acre*

23 There were •25 nue. of magnesium per 100 grams of surface soil, and .21 m.e. per 100 grams of subsoil.

There were 2.42 m.e. of calcium per 100

grams of surface soil, and 1.79 m.e. of calcium per 100 grams of subsoil. The readily available phosphorus of the surface and subsoil was 51*5 and 186.0 pounds per acre, respectively.

Total per cent nitrogen in the soil

was .13, or 2.60 per cent organic matter. The soil at location 5 was a Bronson fine sandy loam.

To a depth of

8 inches the surface soil is light yellowish-brown to brownish-gray fine sandy loam.

At a depth of about 18 inches the subsoil is mottled yellowish

and gray sandy gravelly clay loam, sticky when wet and hard when dry. substratum is stratified gravel and coarse sand.

In extremely wet periods

crops may suffer somewhat from too much water.The topography level (71)*

The

is nearly

The pH of the surface soil ran about 6.0, and the average pH

of the subsoil was 6.4*

The exchangeable potassium of the surface soil was

.29 m.e. per 100 grams of soil, or 276 pounds of potash per acre.

Exchange­

able potassium of the subsoil was .13 m.e. per 100 grams of soil, or 120 pounds of potash per acre.

There were .36 m.e. of magnesium per 100 grams

of surface soil, and .25 m.e. per 100 grams of subsoil.

There were 2.25 m.e.

of calcium per 100 grams of surface soil, and 1.49 m.e. per 100 grams of sub­ soil.

The readily available phosphorus of the surface and subsoil was 71.6

and 262.0 pounds per acre, respectively.

Total per cent nitrogen in the soil

was .12, or 2.40 per cent organic matter. A Miami fine sandy loam existed at location 6. yellowish-brown and a fine sandy loam. of sand, silt, and clay.

The subsoil is composed of a mixture

The sandy texture of the surface soil subjects

crops to injury from drought. drainage is good (71).

This soil is light

The relief is undulating to rolling and the

The pH of the surface soil and subsoil was 6.8 and

24 6*0, respectively.

The exchangeable potassium of the surface soil was

.32 m.e. per 100 grams, or 284 pounds of potash per acre.

Exchangeable

potassium of the subsoil was .23 m.e. per 100 grams, or 216 pounds of potash per acre.

The exchangeable magnesium of the surface soil and sub­

soil was .29 and .42 m.e. per 100 grams of soil, respectively.

The ex­

changeable calcium of the surface soil and subsoil was 3.15 and .64 m.e. per 100 grams of soil, respectively.

The readily available phosphorus of

the surface soil and subsoil.was 53.5 and 144.0 pounds per acre, respective­ ly.

Total per cent nitrogen in the soil was .11, or 2.20 per cent organic

matter. The soil at location 7 was a Miami loam.

The surface soil is usually

light yellowish-brown friable loam, much darker when wet. ent and aeration and internal drainage are good. of a mixture of sand, silt, and clay. and the drainage is good (71). 6.1 and 6.3, respectively.

Tilth is excell­

The subsoil is composed

The relief is undulating to rolling

The pH of the surface soil and subsoil was

The exchangeable potassium of the surface soil

was .40 m.e. per 100 grams of soil, or 372 pounds of potash per acre.

Ex­

changeable potassium of the subsoil was .31 m.e. per 100 grams of soil, or 288 pounds of potash per acre.

The exchangeable magnesium of the surface

soil and subsoil was .36 and .42 m.e. per 100 grams of soil, respectively. The exchangeable calcium of the surface soil and subsoil was 3*66 and 5.02 m.e. per 100 grams, respectively.

The readily available phosphorus of the

surface and subsoil was 123.6 and 276.0 pounds per acre, respectively. Total per cent nitrogen in the soil was .17, or 3*40 per cent organic matter. Application of Fertilizers

Phosphorus and potassium fertilizers were

each applied at three rates in all possible combinations.

Nitrogen was

25 applied at three rates ■with a high level of phosphorus and potassium. It was applied in the spring with the other fertilizers, or in summer immediately after the forage harvest*

Magnesium and boron were each

applied at one rate with a high level of phosphorus and potassium. The levels of phosphorus fertilization were 0, 100, and 300 pounds of P205 per acre, applied as superphosphate. The levels of potash were 0, 50, and 150 pounds of IC^O per acre, applied as muriate of potash.

Levels

of nitrogen fertilization were 0, 40, and 120 pounds of nitrogen per acre, applied as ammonium nitrate.

Boron fertilization consisted of applying 25

pounds of borax with 300 pounds of phosphorus and 150 pounds of potassium per acre.

Magnesium fertilization consisted of applying 100 pounds of mag­

nesia (MgO) as MgS0^«7H20 per acre with 300 pounds cf phosphorus and 150 pounds of potassium. Fertilizer treatments were broadcast by hand as a top dressing at lo­ cations 1, 2, 3, 4, 5, 6, and 7 on April 11, 12, 12, 13, 13, 14, and 15, respectively.

Precaution was taken to control drift of fertilizers by broad­

casting very close to the ground when there was very little air movement. The delayed nitrogen treatment was applied immediately after the forage har­ vest at each location. Field Methods and Harvesting Techniques

Clover plots were harvested

for forage between the one-tenth and one-half bloom stage at locations 1, 2, 3, 4, 5, 6, and 7 on June 10, 11, 11, 12, 13, 16, and 17, respectively.

A

power driven sickle-bar mower 38 inches wide was used to cut the clover approximately two inches from the surface of the soil.

A 12-inch strip was

cut from each end of the plots as border then a swath the width of the mower was cut down the center of the plots. This gave a border at each end of 24

26 inches and a border of 34 inches on each side of the plot. cut, raked, and weighed.

Each plot was

In order to reduce the number of moisture samples,

approximately 500 gram samples were obtained immediately after cutting from every sixth plot.

These damples were weighed and reduced to constant

weight in a forced air dryer operating at approximately 160°F.

The mean

moisture percentage obtained by sampling every sixth plot was used for the entire test at any given location.

The forage yields were calculated as

tons per acre at 12 per cent moisture. It was necessary to spray all locations in order to control leafhoppers and grasshoppers.

On July 18 and 19, plots were sprayed with 2 pounds of

DDT and one-half pound of 6 per cent gamma isomer of benzene hexachloride per acre. A seed harvest was taken at locations 1, 2, 3, 4, 5> 6, and 7 on August 18, 19, 20, 21, 22, 29, and 30, respectively.

A sampling technique con­

sisted of placing a 1 by 3 foot rectangular wooden frame, which stood two inches from the surface of the soil, within each plot.

Clover heads within

this 1 by 3 foot area, including those on the ground, were picked, counted and placed in numbered kraft paper bags.

These bags were folded and stapled.

Four such samples were taken through thecenter of each plot. The paper bags were allowed to dry atapproximately seed was threshed with a mechanical cloverhuiler*

Seed

80°F. before the yield data were

calculated as pounds of seed per acre. Laboratory Methods

It was believedthat the different fertilizer

treatments might affect the size and development of the clover seeds, so 100 seeds were counted and weighed on an analytical balance.

These data were

recorded as weight of 100 clover seeds, expressed in milligrams.

27 All data were subjected to an analysis c£ variance, and least signi­ ficant differences were calculated when the F values were significant» Correlation coefficients were also calculated»

28 EXPERIMENTAL RESULTS The Effect of Methods and Rates of Seeding Clover Alone and With Oat Companion Crops on Seed Production of Red Clover The 1947 and 1943 growing seasons were characterized by an adequate supply of moisture throughout most of the spring and summer months. In 1947, June was the only month in which rainfall was below the forty year average (79),

Monthly mean temperatures were slightly below normal for

the entire growing season during 1947,

Favorable temperature conditions

existed during the 1943 growing season* The two oat varieties used in this experiment differed considerably in respect to their growth characteristics*

Benton was taller, heavier-

strawed, and matured about seven days later than Neosho*

Both varieties

were removed from the clover plots when they had reached the dough stage of maturity*

It was noted that the Neosho oats had a tendency to lodge

just after heading* It was observed throughout the summer of 1947 that clover plants were much smaller when grcxra in association with either of these oat varieties than when grown alone.

This condition was quite general throughout the

entire experiment and existed until the clover was cut on September 2, 1947* Bloom Ratings Relative to the 1947 Forage Harvest

The relative bloom

ratings of red clover on August 4, 11, and 28, 1947 are shown in Tables 1, 2, and 3, respectively*

The estimate of bloom on August 4 was taken when

the clover plants were just coming into bloom, thus affording a comparative measure of earliness of bloom for all treatments * As shown in Table 4, the bloom differences for companion crops were highly significant at the 1 per cent point for all dates.

A highly significant variance ratio also was

29

Table 1.

Bloom Rating on August 4» 1947 as Influenced by Methods and Rates of Seeding Red Clover Alone and With Oat Companion Crops*

Mean Bloom Rating^Oat Companion Crop

Rate of Seeding Clover in Pounds/Acre____ 8______ 12_____ 16_____________ Average

Broadcast None Benton Neosho Average

3*33 0.67 0.67 1*56

2.33 0.33 0.33 0.99

2.33 0.67 0.33 1.11

1.67 0.67 0.00 0.78

2.4L 0.58 0.33 1.11

2.00 0.67 0.67 1.11

1.33 0.33 0.33 0.66

2.42 0.58 0.50 1.17

1.67 0.33 0.00 0.67

1.33 0.67 0.00 0.6?

1.83 0.41 0.16 0.80

2.00 0.56 0.33 0.96

1.44 0.56 0.11 0.70

2.22 0.53 0.33 1.02

0*51 0*70 0*34 0*45

0726 0*35 0.17 0*22,

7 inches None Benton Neosho Average

3*67 0*33 0.33 1.44

2.67 1.00 0.67 1.45 14 inches

None Benton Neosho Average

2*67 0.33 0.33 l.H

1.67 0.33 0.33 0.78 Average

3*22 0*44 0*44 1.37

None Benton Neosho Average L«S*D* L.S.D. L*S*D* L.S.D*

for for for for

2.22 0.55 0.44 1.07

companion crop at the 5$ level companion crop at the 1% level rate of seeding at the 5^ level rate of seeding at the 1^ level

-L 0 * no bloom; 10 sr complete bloom (

30

Table 2#

Bloom Eating on August 11, 1947 as Influenced by Methods and Rates of Seeding Red Clover Alone and With Oat Companion Crops •

Mean Bloom Rating^* ------Rate of Seeding Clover in Pounds/Acre________

Oat Companion Crop _________________

4______ 8______ 12_____ 16______________Average Broadcast

None Benton Neosho Average

4.67 1.00 1.00 2.22

3.67 0.67 1.00 1.78

3.33 1.00 1.00 1.78

2.33 0.67 1.00 1.33

3.50 0.83 1.00 1.78

3.00 1.00 1.00 1.67

2.33 0.67 1.00 1.33

3.58 0.92 1.00 1.83

2.33 0.67 1.00 1.33

2.00 ' 1.00 1.00 1.33

2.67 0.83 1.00 1.50

2.89 0.89 1.00 1.59

2.22 0.78 1.00 1.33

3.25 0.86 1.00 1.70

7 inches None Benton Neosho Average

5.33 1.00 1.00 2.44

3.67 1.00 1.00 1.89 14 inches

None Benton Neosho Average

3.67 1.00 1.00 1.89

2.67 0.67 1.00 1.45 Average

None Benton Neosho Average L#S*D. L.S.D. L.S.D. L.S.D.

for for for for

4.56 1.00 1.00 2.18

3.34 0.78 1.00 1.70

companion crop at the 5$ level companion crop at the 1$ level rate of seeding at the 5% level rate of seeding at the 1% level____

0 s no bloom; 10 = complete bloom

0*23 0.32 0.40 0.54_____________

0.12 0.16 0.20 0.27

31

Table 3*

Bloom Rating on August 28, 1947 as Influenced by Methods and Rates of Seeding Red Clover Alone and With Oat Companion Crops •

Mean Bloom Rating^-______ Oat Companion Crop

Rate of Seeding Clover in Pounds/Acre 4______ 8______ 12

16

Average

Broadcast None Benton Neosho Average

8.67 6.00 6.67 7.11

9.00 6.33 6.67 7.33

9.33 6.67 6.33 7.44

7.33 5.33 6.67 6.44

8.58 6.08 6.58 7.08

8.33 7.33 6.33 7.33

7.67 6.67 6.67 7.00

8.25 7.33 6.41 7.33

8.00 5.67 6.67 6.78

7.33 7.00 6.67 7.00

8.08 6.33 6.50 6.97

8.55 6.56 6.44 7.18

7.44 6.33 6.67 6.81

8.30 6.58 6.67 7.13

7 inches None Benton Neosho Average

9.33 8.00 6.33 7.89

7.67 7.33 6.33 7.11 14 inches

None Benton Neosho Average

3.67 6.67 6.33 7.22

8.33 6.00 6.33 6.89 Average

None Benton Neosho Average

8.89 6.89 6.44 7.41

8.33 6.55 6.44 7.H

L*S*D. for companion crop at the 5% level 0*59 0.30 L.S.D. for companion crop at the 1% level 0.81 ' 0.41 L.S.D. for rate of seeding at the 5% level_____ 0.4Q______________ 0*20 0 » no bloom; 10 » complete bloom

32 Table 4«

F Values for Methods and Rates of Seeding Glover, Oat Companion Crops, and Replications with 2/l6, 3/54> 2/l6, and 2/l6 Degrees of Freedom, respectively*

Data Analyzed Date Forage Yield of Clover Forage Yield of Clover Stand Rating of Clover Stand Rating of Clover Seed Yield of Clover Bloom Rating of Clover Bloom Rating of Glover Bloom Rating of Clover Bloom Rating of Clover Bloom Rating of Clover Bloom Rating of Clover Bloom Rating of Clover Bloom Rating of Clover

9-2-47 6-8-48 10-20-47 4-30-48 8—28—48 8—4—47 8—11—47 8—28—47 6—3—48 6—8—48 6—30—48 7-13-48 7—20—48

F Values Rates of Companion Methods Seeding Replications Crop 2.20 5.20* 3.6?* 6*40 1.08 1.31 0.54 0.85 5.00* 1.12 1.75 0.13 2.26

1.77 1.81 4.79** 2.07 1.77 5.85** 6.73 2.93* 2.00 4.63** 1.40 1.04 0.94

72.37** 1.08 0.33 1.47 2.76 37.76** 30.53** 26.75** 2.10 0.83 0.85 2.14 0.05

11.04** 2.04 0.05 0.2? 1.51 8.19** 2.44 2.07 3.48 2.42 0.37 7.00** 7.58**

# Significant at the 5 per cent point* **Significant at the 1 per cent point* obtained for rates of seeding clover*

A nonsignificant variance ratio was

obtained for methods of seeding clover. As shown in Table 1, clover grown alone had an average bloom ratipg of 2.22; while, clover grown with Benton and Neosho had an average bloom rating of 0*52 and 0.33, respectively.

The bloom difference between Benton and

Neosho was not significant, but both varieties differed significantly from the no companion crop treatment.

This relationship also was present in the

bloom ratings taken on August 11 and August 28.

Thus, clover grown alone

produced more bloom than with either oat variety. Rates of seeding clover had s significant effect upon the amount of bloom.

It will be noted that the 4 pound rate of seeding produced more

relative bloom than any of the higher rates of seeding.

Bloom consistently

33 decreased with increased rates of seeding clover. The highly significant variation between replications was probably due to variable soil and environmental conditions. 1947 Forage Yield of Clover 1947 are shown in Table 5»

Forage yield data taken on September 2,

The differences in forage production for com­

panion crops were highly significant.

Clover seeded alone produced more

forage than when grown in association with Benton or Neosho. ences in yield of forage were very pronounced.

These differ­

Clover alone averaged 1.32

tons per acre, and only 0.52 and 0.65 tons per acre when grown with Benton and Neosho, respectively.

It will be noted that the yield difference be­

tween Benton and Neosho was highly significant.

The taller, heavier-strawed,

and later maturing Benton oat was more effective in reducing growth of the clover than Neosho.

This condition is in complete agreement with results

obtained by the author in a previous study (13). Differences in forage yield due to methods of planting the clover were not significant.

The average yield for broadcast, 7 inch row spacing, and

14 inch row spacing was 0.88, 0.88, and 0.74 tons per acre, respectively. The very small differences in forage yield due to rates of seeding also were not statistically significant.

Clover seeded at 4 pounds per acre

produced as much forage as clover seeded at 8, 12, or 16 pounds per acre. The highly significant variation between replications could be attrib­ uted to variable soil and environmental conditions. A highly significant relationship was found to exist between bloom ratings on August 4» 11, and 28 and the forage yield of clover, as may be seen in Table 6.

The correlation coefficient for the relationship between

bloom rating on August 4, 11, and 28 and forage yield of clover was 4-0.8407,

34 f0.8433, and. f0.7033, respectively. Table 5*

The Effect of Methods and Rates of Seeding Clover Alone and with Oat Companion Crops on the Forage Yield of Red Clover, September 2 , 1947

Oat Companion Crop

Mean Forage Yield in Tons/Acre-^Rate of Seeding Clover in Pounds/Acre 8 ______ 12_____ 16_______ ; _____ Average

Broadcast None, Benton Neosho Average

1.15 0.57 0 .7 6 0.83

1.37 0 .6 0 0.79 O .9 2

1.29 0 .6 8 0.67 0 .8 8 .

1.26 0.62 0 .7 6 0 .8 8

1.27 0 .6 2 0.74 0 .8 8

1.31 0 .6 1 0 .7 0 0.87

1.14 0 .7 0 0.75 0*86

1.34 0.59 0.71 0 .8 8

1.28 0.47 0.47 0.74

1.33 0.33 0.54 0.75

1.34 0 .3 6 0.51 0.74

1.29 0.59 0 .6 1 0.83

1 .2 6 0.55 0 .6 8 0.83

1.32 0 .5 2 0.65 0.83

6705 0.06

0*03 QsP?.

7 inches None Benton Neosho Average

1.41 0.45 0.64 0.83

1.52 0 .6 0 0 .7 6 0.96 14 inches

None Benton Néosho Average

1.31 0 .3 0 0.53 0.71

1.39 0.33 0.51 0.74 Average

None Benton Neosho Average

1.29 0.44 0.64 0.79

1.43 0.51 0.69 0.87

L.S.D. for companion crop at the 5$ level LéS.D. for companion crop at the X% level 1 Calculated at 12 per cent moisture

Stand of Clover

The clover stand was estimated on October 20, 1947,

as shown in Table 8 . Stand differences due to methods of planting the clover were significant at the 5 per cent point.

As shown in Table 8 , the

35 Table 6.

Correlation Coefficients for the Relationship between Forage, Stand, Bloom, and Seed Data of Red Clover

Correlation Between Date Bloom Rating Bloom Rating Bloom Rating Ave. Rating Bloom Rating Bloom Rating Ave. Rating Bloom Rating Bloom Rating Bloom Rating Ave. Rating Forage Yield Forage Yield Forage Yield Forage Yield Forage Yield Stand Rating Stand Rating

8—4—47 8-11-47 8-28-47 8-4,11,28 6—3—48 6—8—48 6—3,6—8 6-30-48 7-13-48 7—20—48 6-30,7-13,7-20 9-2-47 9-2-47 9-2-47 9—2—47 6—8—48 4-30-48 4—30—48

Date

Forage Yield Forage Yield Forage Yield Forage Yield Forage Yield Forage Yield Forage Yield Seed Yield Seed Yield Seed Yield Seed Yield Forage Yield Stand Rating Stand Rating Seed Yield Seed Yield Forage Yield Seed Yield

9—2—47 9-2-47 9-2-47 9—2—47 6—8—48 6—8—48 6—8—48 8—28—48 8—28—48 8—28—48 8—28—48 6—8—48 10—20—47 4—30—48 8—28—48 8—28—48 6—8—48 8—28—48

Correlation Coefficient +0.8407** +0.8433** +0.7033** +0.8461 +0.1481 +0.2132 +0.2142 +0.1399 -0.3835* -0.1873 +0.2424 —O.O846 +0.2804 +0.0467 -O.5094** +0.2258 +0.5059** +0.3758*

* Significant at the 5% level ■^Significant at the level Table 7.

Total, Partial, and Multiple Correlation Coefficients for the Relationship between Stand, Forage, and Seed Data of Red Clover

Correlation Between Date

Date

Partial Multiple Total Correlation Correlation Correlation

Forage Yield 9-2-47 Forage Yield 6-8-48 -0,0846 -0.1207 Forage Yield 9-2-47 Stand Rating 4-30-48 +0.0467 +0.2586 Fora g3 Yield 9-2-47 Seed Yield 8-28-48 -0.5094** -0.4647** Forage Yield 6-8-48 Seed Yield 8-28-48 +0.2258 +0.0043 Stand Rating 4-30-48 Forage Yield 6-8-48 +0.5059** +0.4837** Stand Rating 4-30-48 Seed Yield 8-28-48 +0.3758* +0.3673* Stand,1947>1948 Forage Seed Yield 8-28-48 * Significant at the 5% level **Signifi cant at the 1% level

+0.3756

36 Table 8*

Stand Rating of Red Clover on October 20, 1947 as Affected by Methods and Rates of Seeding Clover Alone and With Oat Companion Crops.

Mean Stand Rating^ Oat Companion Crop

Rate of Seeding Clover in Pounds/Acre 4

8

12

16

Average

Broadcast None Benton Neosho Average

10.00 9.33 8.66 9.33

9.33 10.00 10.00 9.73

9.66 10.00 10.00 9.39

10.00 10.00 10.00 10.00

9.75 9.83 9.66 9.75

10.00 10.00 10.00 10.00

10.00 10.00 9.92 9.97

9.66 10.00 10.00 9.39

10.00 9.33 10.00 9.73

9.53 9.58 10.00 9.72

9.77 10.00 10.00 9.92

10.00 9.73 10.00 9.92

9.77 9.80 9.96 9.81

0.21 0.20 0.27

0.11 0.10 0.14

7 inches None Benton Neosho Average

10.00 10.00 10.00 10.00

10.00 10.00 9.66 9.39

10.00 10.00 10.00 10.00

14 inches None Benton Neosho Average

9.00 9.33 10.00 9.44

9.66 9.66 10.00 9.77 Average

None Benton Neosho Average

9.67 9.55 9.55 9.59

9.66 9.39 9.39 9.31

L.S.D. for Method at the 5% level LeS.D. for rate of seeding at the 5% level L.S.D. for rate of seeding at the 1$ level 1 0 — no stand5 10 = complete stand

highest stand rating was obtained when clover was drilled in rows 7 inches apart.

The average stand rating for broadcast, rows spaced 7 inches, and

37 rows spaced 14 inches was 9.75, 9.97, and 9.72, respectively.

Thus,

clover drilled in rows spaced 7 inches was. able to maintain better stands than when broadcast or drilled in rows spaced 14 inches. Rates of seeding clover had a significant effect upon the stand dur­ ing the first growing season.

It will be noted that high stand ratings

were associated with increased rates of seeding.

Stand consistently in­

creased with increased rate c£ seeding. There was no significant difference between the clover stands for clover grown alone, with Benton, or Neosho. Another stand rating was taken in the spring of 1943. These presented in Table 9.

data are

Stand differences for methods were highly significant.

The average stand rating for broadcast, rows spaced 7 inches, and rows spaced 14 inches was 7.73, 3.66, and 7.55, respectively.

These data are in

complete agreement with stand determinations for the fall of 1947. It will be observed that stand progressively increased with increased rate of seeding; however, these differences in stand were not significant. The F value of 2.07 approached the 5 per cent point of significance, which was 2.78. It is of interest to note that companion crops did not differ signif­ icantly with respect to their effects on clover stand.

As may be seen in

Table 9, the average stand rating for clover grown alone, with Benton, and with Neosho was 7.94, 8.30, and 7.75, respectively.

The clover stand was

slightly better when grown with Benton; yet, Benton significantly reduced the forage yield of clover in 1947. Bloom Ratings Relative to the 1943 Forage Harvest

The relative bloom

ratings of red clover on June 3, and 8, 1948 may be seen in Tables 10 and

3d Table 9*

Stand Rating of Red Clover on April 30, 1948 as Affected by Methods and Rates cf Seeding Clover Alone and With Oat Companion Crops

Mean Stand Rating?* Oat Companion Crop

Rate of Seeding Clover in Pounds/Acre 4

8

Average

12

16

8.00 8.00 7.67 7.89

9.00 8.67 8.33 8.67

7.83 7.83 7.67 7.78

8.33 10.00 8.00 8.78

10.00 10.00 9.33 9.78

8.41 9.33 8.25 8.66

7.33 8.33 7.67 7.78

8.67 8.33 8.00 8.33

7.58 7.75 7.33 7.55

7.89 8.78 7*78 8.15

9.22 9.00 8.55 8.92

7.94 8.30 7.75 7.99

Broadcast None Benton Neosho Average

6.33 6.67 6.67 6.56

8.00 8.00 8.00 8.00 7 inches

None Benton Neosho Average

7.33 8.00 7.00 7.44

8.00 9.33 8.67 8.67

14 inches None Benton Neosho Average

6.67 6.33 6.33 6*44

7.67 8.00 7.33 7.67 Average

None Benton Neosho Average

6.78 7.00 6.67 6.81

7.89 8.44 8.00 8.11

L.S.D. for method at the 5% level L.S.D. for method at the 1$ level__________

0.22 0*11 0*3Q______________ 0*3-5

0 = no stand; 10 = complete stand 11, respectively.

Bloom differences for methods of planting clover were

statistically significant.

Clover drilled in rows spaced 14 inches had an

average bloom rating of 2.945 while, clover broadcast or drilled in rows

39 Table 10.

Bloom Rating on June 3» 1948 as Influenced by Methods and Rates of Seeding Red Clover Alone and With Oat Companion Crops

Mean Bloom Rating^Oat Companion Crop

Rate of Seeding Clover in Pounds/Acre 4

12

16

2.33 3.33 2.33 2.66

1.67 2.67 3.00 2.45

2.08 2.75 2.50 2*44

2.67 2.67 2.67 2.67

2.67 2.00 2.67 2.45

2.75 2.42 2.58 2.58

8

Average

Broadcast None Benton Neosho Average

2.33 2.33 2.67 2.44

2.00 2.67 2.00 2.22 7 inches

None Benton Neosho Average

None Benton Neosho Average

3,00 3.00 2.67 2.89

2.67 3.67 3.00 3.H

2.67 2.00 2.33 2.33 14 inches

*

2.67 3.33 2.33 2.78

2.67 3.33 2.67 2.89

2.67 3.00 3.33 3.00

2.67 3.33 2.83 2.94

2.56 3.11 2.56 2.74

2.34 2.56 3.00 2.63

2.50 2.83 2.64 2.65

0.36

0.18

Average None Benton Neosho Average

2.67 3.00 2.78 2.81

2.45 2.67 2.22 2.44

L.S.D. for method at the 5% level 0 — no bloom; 10 = complete bloom

spaced 7 inches had an average rating of 2.44 and 2.58, respectively (Table 10).

It may be seen in Table 11 that this relationship also existed in

the bloom ratings taken on June 8. nificant.

However, the differences were not sig­

Clover planted in rows spaced 14 inches bloomed earlier and

40 Table 11*

Bloom Rating on June 8, 1948 as Influenced by Methods and Rates of Seeding Red Clover Alone and With Oat Companion Crops

1 Mean Bloom Rating Companion Crop

Rate of Seeding Clover in Pounds/Acre 4

8

Average

12

16

6.33 7.00 6.33 6.55

5.33 6.67 6.6? 6.22

5.91 6.50 6.25 6.22

6.33 6.67 6.33 6.44

6.33 5.67 6.67 6.22

6.50 6.08 6.41 6.33

6.33 7.00 6.67 6.66

6.00 7.00 7.33 6.78

6.16 7.08 6.67 6.64

6.33 6.89 6.44 6.55

5.89 6.45 6.89 6.41

6.19 6.55 6.44 6.39

0.40 0.54

0.20 0*27

Broadcast None Benton Neosho Average

6.33 6.33 6.33 6.33

5.6? 6.00 5.67 5.78 7 laches

None Benton Neosho Average

7.00 6.67 6.33 6.66

6.33 5.33 6.33 5.99 14 inches

None Benton Neosho Average

6.33 7.33 7.00 6.88

6.00 7.00 5.67 6.22

x

Average None Benton Neosho Average

6.55 6.78 6.55 6.63

6.00 6.11 5.89 6.00

L.S.D. for rate of seeding atthe 5$ level L.S.D. for rate of seeding atthe 1% level ^ 0

s

no bloom; 10 = complete

bloom

maintained more bloom, throughout the blooming period than either broad­ cast or rows spaced ? inches. Bloom differences due to companion crops were not significant on

41 either date.

It will be noted that clover grown with Benton had a higher

bloom rating than with Neosho or alone. Rates of seeding clover had a highly significant effect upon the amount of bloom on June 8.

The 4 pound rate of seeding produced more rel­

ative bloom than any of the higher rates of seeding.

This relationship also

was present on June 3> however, the differences were not statistically sig­ nificant. 1948 Forage Yield of Clover are shown in Table 12.

Forage yield data taken on June 8, 1948

The differences in yield of forage for methods of

planting clover were significant at the 5 per cent point.

The average yield

for broadcast, rows spaced 7 inches, and rows spaced 14 inches was 2*63, 2.66, and 2*42, respectively.

Thus, clover drilled in rows spaced ? inches

was the most desirable method from the standpoint of forage production. Conversely, clover drilled in rows spaced 14 inches was the least desirable method. The differences in forage yield due to companion crops were not signifi­ cant.

Clover grown alone produced an average yield of 2.51 tons per acre;

whereas, clover grovn with Benton and Neosho produced 2.66 and 2.54 tons per acre, respectively. Rates of seeding did not significantly affect the forage yield.

How­

ever, slightly higher yields usually were obtained with increased rate of seeding. A highly significant correlation coefficient of 10.5059 was obtained for the relationship between stand and yield cf clover forage.

This sig­

nificant relationship between stand and yield indicates that the method of determining stand is probably reliable, since it apparently measured those

42 stand differences which contributed to differences in yield cf forage* Bloom Eatings Relative to Seed Yield

Bloom ratings proceeding the

seed harvest on August 28 are shown in Tables 23 > 14, and 15 • Bloom differ­ ences for methods and rates of seeding clover, and companion crops were not significant on any date* Clover grown with Benton again produced more bloom than with either Neosho or alone.

In addition, clover grown in association with either com­

panion crop oroduced more bloom than alone.

These relationships were con­

sistent for all three dates. Seed Yield of Clover

Seed yield data are presented in Table 16.

It

will be noted that methods of planting the clover slightly influenced the seed yield.

Drilling clover in rows spaced 7 inches was again the most

desirable method.

Yet, these differences were not significant at the 5

per cent point. Differences in seed yield due to companion crops also were not statis­ tically significant*

The F value for companion crops was 2.76 while sig­

nificance at the 5 per cent point was 3*63* desirable companion crop*

Benton was again the most

In addition, clover grown in association with

either companion crop produced more seed than alone. There was a tendency for seed yield to increase ydth increased rate of seeding; however, these differences were not significant* A highly significant correlation coefficient of -0.5094 was obtained for 1947 forage yield and 1948 seed yield. was associated with decreased seed in 1948*

Thus, increased forage in 1947 A significant correlation

coefficient of *0.3758 was obtained for 1948 stand and seed yield.

A non-

43 Table 12»

The Effect of Methods and Rates of Seeding Clover Alone and With Oat Companion Crops on the Forage Yield of Red Clover, June 8, 1948

Mean Forage Yield in Tons/A 6, and ?*

This was probably caused by an excess of phosphorus in

proportion to the supplies of other required nutrients, which could have hastened the maturation processes and reduced vegetative growth. It is believed that phosphorus was available to the clover plants since the pH was above 5.0 at all locations*

It is known that from about pH 5.0

up to the neutral point, soil phosphates have an appreciable solubility due to the basic ions present that maintain the higher pH and at the same time fora some calcium and magnesium phosphates in the soil.

If the soils had

been below pH 5.0, one might normally expect phosphorus to be unavailable since complex phosphates of iron and aluminum would be expected to be formed which have a very low solubility*

80 It will be recalled that increased applications of phosphorus usually decreased the number of clover heads produced and seed yield at all locations* There was a significant positive correlation between the number of clover heads and seed yield at each location.

Phosphorus fertilization markedly

decreased the seed yield because the production of clover heads was decreased. One might normally expect phosphorus fertilization to increase the seed yield, since it is an important constituent of all seeds.

In addition, phosphorus

is known usually to hasten maturity and promote seed development.

However,

an excess of phosphorus in the soil in proportion to the supplies of other required nutrients probably resulted in an excess of phosphorus in the plant due to "luxury absorption".

The excess phosphorus in the clover plant could

have caused a condition of physiological imbalance which decreased growth and the production of clover heads. It is also believed that the excessive amount of phosphorus in propor­ tion to the supplies of other required nutrients in the soil could have minimized the production of clover heads by limiting the absorption of nitro­ gen.

For instance, it has been found that low availability of phosphorus

is often associated with a very high content of nitrogen in plants, aid a high content of phosphorus with a low content of nitrogen (11).

Thus, plants

apparently are capabl;e of absorbing phosphorus at the expense of nitrogen when phosphorus is present in a larger proportion.

This probable decreased

absorption of nitrogen could have been responsible for decreased flowering by creatirg a very high carbohydrat e-nitrogen ratio which was not conducive to reproduction. Seed weight usually was higher with the 100 pound application of phos­ phorus than the 0 or 300 pound application.

This relationship, even though

not significant, suggests that the 100 pound level of phosphorus probably

81 was nearer to the optimum for seed development than ths 0 or 300 pound level* Potassium

The influence of potassium fertilization upon factors

affectirg seed production of clover is summarized in Table 37* Table 37*

Lbs. of Per Acre 0 50 150

The Influence of Potassium Fertilization upon Factors Affecting Seed Production of Red Clover

Average Forage Yield in Tons/Acre 2.07 2.16 2.24

Average No. of Clover Heads Per 12 Sq. Ft. 347.10 347.04 324*64

Average Seed Weight in Milligrams Per 100 Seeds

Average Seed Yield in Pounds Per Acre 27.08 28.63 28.10

155*6 157.3 157.3

All locations gave a slight response to potassium fertilization.

Soil

analyses showed that all locations ranked high in respect to exchangeable potassium.

Thus, one would not expect a marked response to potassium ferti­

lization, since it was not a limiting factor for plant growth*

As shown in

Table 37, potassium fertilization did slightly increase the forage yield and seed weight, but it had relatively little effect on the average production of clover heads cr seed yield.

However, at locations 2, 3» 5, and 6 increased

applications of potassium decreased the number of clover heads and seed yield, especially with the 150 pound application.

This condition was especially

pronounced at location 3, which had a very high analysis of exchangeable po­ tassium. It is believed that the excessive amount of potassium in proportion to the supplies cf other required nutrients in the soil could have limited the production of clover heads by creating a condition of physiological imbalance

82 in the plant*

It has been found that potassium fertilization usually lowers

the phosphorus and nitrogen concentrations of plants (38).

Thus, the rela­

tively high concentration of potassium in the soil could have influenced the production cf clover heads Icy limiting the absorption cf phosphorus and nitrogen*

The relatively low concentration of phosphorus in the clover

plant could have influenced the maturation processes.

In addition, the

relatively low concentration cf nitrogen in the clover plant may have been influential in decreasing the production cf clover heads by creating a very high carbohydrate-nitrogen ratio: which was not conducive to reproduction* Increased applications of potassium at locations 4 and 7 usually in­ creased the number of clover heads and seed yield; yet, these soils were high in exchangeable potassium.

It is believed that the nutrient balance was

more favorable for growth at either of these two locations than at any of the others.

Thus, potassium probably was nob excessive in proportion to the

other required plant nutrients in the soil* Conditions usually were more favorable for seed production when phos­ phorus and potassium were applied together than alone.

It will be noted

that increased applications cf phosphorus with potassium sli^itly increased the average forage yield.

However, increased applications of phosphorus with

potassium usually decreased the number of clover heads, seed yield, and seed weight.

Yet, the effect of phosphorus applied with potassium was not as

pronounced as when phosphorus was applied alone. Potassium fertilization usually increased the forage yield cf clover when applied in combination with phosphorus. Increased applications of po­ tassium usually decreased the number of clover heads and seed yield • There was some variation between locations with respect to the optimum ^0-y©i cf phosphorus and potassium vhen applied together*

It is believed

83 Table 38*

The Influence of Phosphorus and Potassium Fertilization upon Factors Affecting Seed Production of Red Clover

Lbs. of PgO- Per Acre

Lbs. of KpO Per Acre

Average Forage Yield in Tons/Acre

Average No. of Clover Heads/12, Sq.Ft*

Average Seed Yield in Pounds Per Acre

Average Seed Weight in Milligrams Per 100 Seeds

100 100 100

0 50 150

2.84 3.07 2.87

313.54 302.11 302.29

25.57 22.53 23.35

157.5 157.5 159.0

300 300 300

0 50 150

2*71 3.09 3.11

298.00 285.71 292.89

18.91 23.59 20.98

153.7 155.9 156.8

that a balance of required nutrients must exist in the soil for maximum growth and seed production*

Environmental conditions probably are as im­

portant in regulating growth and the maturation processes as the amount of nutrient applied to the soil.

Moisture relations in the soil would be ex­

pected to influence the availability of nutrients and their absorption* Aeration also would be expected to influence the absorption of ions by the roots9 since it is generally recognized that ions accumulate rapidly in plants with increased aeration*

A high rate of aerobic respiration is usually re­

quired for increased accumulation of both cations and anions in the root cells* Thus, factors affecting respiration would be expected to influence the ab­ sorption of plant nutrients in the soil.

It is well established that the

energy of respiration might be the important factor in the accumulation and retention of ions*

Soil temperature also could be influential in determining

the absorption of nutrients, since it is known that temperature is important in the growth and metabolism of plants * The extent of the root systems of the plants probably influences the amount of mineral absorption* The absorption cf solutes by plants is influenced by many factors in the

84 snvironment and is not so simple as applying salts to the soil with the anticipation of obtaining certain results•

The application cf any given

fertilizer cr fertilizers to a particular soil at one location mi^it not give the same response as when applied to another soil at a different lo­ cation, since the plants would probably be growing under different environ­ mental conditions.

It is believed that this diversity in environmental con­

ditions could have been partially responsible for the variation between lo­ cations in response to fertilization. It is interesting to note that potassium fertilization consistently in­ creased the weight of clover seeds*

This might be expected since it has been

found that potassium usually increases plumphess in grains, producing greater test weight per bushel.

It has been suggested that potassium is involved

in the manufacture of protein in the plant cell*

This theoiy is strengthened

by the fact that increased protein reserves in seeds are often associated with an increase in potassium content* Nitrogen

The influence of rate and time of application of nitrogen

fertilization upon factors affecting seed production of clover is summarized in Table 39* Nitrogen fertilization usually increased the forage yield of clover slightly, and decreased the number of clover heads, seed yield, and seed weight. However, at locations 1 and 3 increased applications of nitrogen actually decreased the forage growth of clover*

It is believed that the

increased applications of nitrogen could have created a low carbohydratenitrogen ratio in the clover plant which was not conducive to reproduction. It is known that a very low proportion of available carbohydrates to avail­ able nitrogen will usually produce plants which are weak vegetatively and unfruitful•

It is also known that a low proportion of available carbohy-

85 Table 39#

The Influence of Rate and Time of Application of Nitrogen Fertilization upon Factors Affecting Seed Production of Red Glover

Lbs. cf Nitrogen/Acre Applied Spring Summer 0 IP

120 0 40 120

Average Forage Yield in Tons/Acre

Average Np. of Clover Heads Per 12 So.Ft.

Average Seed Yield in Pounds Per Acre

3.11 2.99 3.23

292.90 245.50 244.43

20.98 17.29 15.71

156.8 155.0 152.7

292.90 255.95 228.61

20.98 11.37 15.16

156.8 150.5 152.3

■

— —

Average Seed Weight in Milligrams Per 100 Seeds

drates to nitrogen will usually produce plants which are vigorous vegetatively but unfruitful.

The degree of effect was probably influenced by the

available proportion of carbohydrates to nitrogen at each location. The lack of balance between carbohydrates and nitrogen could have de­ creased the seed yield by lack cf pollination and fertilization, since it is known that a 3a ck of balance between carbohydrates and nitrogen sometimes causes sterile pollen and an abnomal development of the pistil in relation to stamen leigth so that pollination cannot take place*

Thus, the lack of

flower formation and fertilization could have been responsible for the de­ crease in seed yield. Time of application of nitrogen had little effect upon the seed yield of clover.

The Ip pound application cf nitrogaa in the summer markedly de­

creased the seed yield in comparison to the same rate applied in the spring; yet, there was very little difference in the production of clover heads be­ tween the spring and summer application.

In addition, the seed weight was

somewhat lower for the summer application than the spring application.

This

86 suggests that the application cf 40 pounds of nitrogen in the summœ probably created a condition of physiological unbalance in the plant which was not conducive to seed development» Magnesium

The influence of magnesium fertilization upon factors affect­

ing seed production of clover is summarized in Table 40» Table 40,

The Influence of Magnesium Fertilization upon Factors Affecting Seed Production cf Red Clover

Lbs. of MgO Per Acre

Average Forage Yield in Tons/Acre 3.26 3.09

0 100

Average Ho. of Clover Heads Per 12 Sq.Ft. 292.90 286.34

Average Seed Yield in Pounds Per Acre

Average Seed Weight in Milligrams Per 100 Seeds

20.98 13.95

156.8 154.4

Magnesium fertilization usually decreased the forage yield, number of clover heads, seed yield, and seed weight. fertilization did give a favorable response.

However, at location 3 magnesium Soil analyses showed that soils

at most locations contained enough magnesium for maximum plant growth.

The

soil at location 3 was relatively low in magnesium, which was probably the reason for increased growth and seed production with magnesium fertilization. It is believed that the excessive amount of magnesium in proportion to the supplies cf other required nutrients in the soil could have limited growth and seed production fcy creating a condition of physiological imbalance in the clover plant.

It is generally recognized that only a small amount of magnes­

ium is needed in the plant to satisfy the requirement for grofth.

As a

matter of fact, it has been found that bean plants can reach their full

87 vegetative growth with no supply cf magnesium other than that stored in the seed. (11).

It is quite probably that the clover plant might have

suffered from magnesium toxicity; however, no foliage symptoms of toxicity were observed. One might expect calcium to overcome any toxic action of magnesium. In addition, the high proportion cf exchangeable potassium in the soil at all locations would be expected to limit the absorption of magnesium, since potassium is more competitive than magnesium with respect to absorption (11, 60).

Yet, the 100 pound application cf magnesium was probably great

enough to disturb the physiological balance in the clover plait, especially since such small amounts are required for normal growth.

The calcium and

potassium in the soil probably acted as buffering agents with respect to the toxic action of magnesium.

It is quite probable that this buffering

action prevented the excessive magnesium in the soil from severely injuring the clover plant. Boron

The influence of boron fertilization upon factors affecting seed

production of clover is summarized in Table 41*

It will be recalled that

the application of 25 pounds of borax per acre consistently decreased the forage yield, number of clover heads, seed yield, and seed weight.

The

soils were not analyzed for boron, but the negative response to fertilization would indicate that it probably was criginally present in sufficient quan­ tities for growth.

The excessive amount cf boron in the soil could have

decreased growth and seed production by toxic action, especially since only very small amounts are required for normal growth and metabolism.

The high

level of exchangeable potassium in the soil at all locations probably accentuated boron toxicity, since it has been found that boron content in

S8 Table 41.

The Influence of Boron Fertilization upon Factors Affecting of Red Clover Seed Production
8, 12, and 16 pounds per acre.

Red clover planted at the low

rate of seeding bloomed earlier and maintained more relative bloom than any of the higher rates of seeding, i.e. bloom in relation to the number of plants.

A greater total bloom at the higher rates of seeding was probably

responsible for the increase in seed yield. Red clover grown in association with either of two oat varieties during the first growing season produced more seed during the second growing season when grown alone.

Oats growing in association with red clover probably

removed enough nitrogen from the soil during the first growing season to limit the fo m a t ion of proteins and permit formation of relatively large amounts of carbohydrates that were stored in the roots of the clover plants, thereby, creating a high carbohydr&te-nitrogen ratio which was conducive to abundant seed production during the second growing season. Pre-bloom spray applications of 2 pounds of 50 per cent wettable DDT powder per acre, 1 pound of toxaphene per acre, and one-half pound of 6 per

90 cent gamma isomer of benzene hexachloride per acre did not significantly affect the seed yield of red clover.

Untreated plots produced as much

clover seed as treated plots. Top dressings of nitrogen, phosphorus, potassium, magnesium, and boron applied alone and together in the spring to second-year stands of red clover significantly affected the seed yield at four of seven experimental locations, ■Applications of 100 and 300 pounds cf phosphorus po* acre to soil al­ ready medium to high in available phosphorus increased the forage yield of red clover, and consistently decreased the number of clover heads, seed yield, and seed weight.

The increased applications of phosphorus probably

resulted in an excess of phosphorus in the clover plant due to “luxury ab­ sorption'1. This excess of phosphorus in the clover plant probably caused a condition of physiological imbalance which decreased growth and the production of clover heads. Potassium applied at 50 and 150 pounds per acre to soil already high in exchangeable potassium increased the forage yield of red clover slightly, but had little influence upon the number of heads, seed yield, or seed weight. In some cases, increased applications cf potassium decreased the number of heads and seed yield of red clover, especially with the 150 pound application. An excessive amount cf potassium in proportion to the supplies cf other re­ quired nutrients in the soil probably limited the production of clover heads by creating a condition of physiological imbalance in the plant. Phosphorus and potassium applied together in different combinations slightly increased the forage yield and seed weight of red clover, but de­ creased the number of heads and the seed weight.

The effect of either

fertilizer on the forage yield, number cf heads, seed yield, and seed weight of red clover was not so great when applied in combination as alone.

The

91

proportion of available phosphorus to exchangeable potassium in the soil was probably nearer to the optimum for maximum growth and seed production when applied together than alone. Nitrogen applied in the spring or immediately after the forage harvest in the summer at 40 and 120 pounds per acre to soil already high in organic matter consistently decreased the number of heads, seed yield, and seed weight of red clover.

Increased applications of nitrogen slightly increased

the forage yield of red clover.

There was very little difference between the

spring and summer applications of nitrogea with respect to forage yield, number of heads, seed yield, and seed weight of red clover.

The increased

applications of nitrogen probably created a low carbohydrate-nitrogen ratio in the clover plant which was not conducive to reproduction. An application of 100 pounds of magnesium to soil already high in ex­ changeable magnesium usually decreased the forage yield,

number of heads,

seed yield, and seed weight

amounb of magnesium

of red clover. An excessive

in proportion to the supplies of other required nutrients in the soil prob­ ably limited growth and seed production by creating a condition of physiolog­ ical imbalance in the red clover plant. An application of 25 pounds of borax per acre to soil which was probably already high in boron slightly decreased the forage yield, number of heads, seed yield, and seed weight

of red clover. An excessive

the soil probably decreased

growth and seed

amount of boron in

production by toxic

action, es­

pecially since only very small amounts are required for normal growth and metabolism.

92 APPENDIX Table I.

Chemical Analyses of Surface Soil at Seven Experimental Locations in Northern Indiana

Lbs of M.e. KoO Per 100 Per Grams of Soil

KpO

Per Cent Location pH 1 2 3 4 5 6 7

7.2 6.4 6.0 6.3 6.0 6.8 6.1

Table II.

Location 1 2 3 4 5 6 7

5.80 3.40 2.60 2*60 2.40 2.20 3.40

318 336 660 276 276 284 _ 372

.34 .36 .72 .29 .29 .32 .40

Lbs of M.e* of M.e. of Mg Per Ca Per 100 grams 100 Grams Acre of Soil .71 .50 .22 .25 .36 .29 .36

34.4 12.6 39.4 51.5 71.6 53.3 123.6

8.09 4.90 1.35 2.42 2.25 3.15 3.66

Chemical Analyses of Subsoils at Seven Experimental Locations in Northern Indiana

Lbs of KgO Per _ PH _ Acre 6.7 6.6 6.0 5.5 6.4 6.0 6.3

216 216 288 144 120 216 288

M.e. of KgO Per 100 Grams of Soil .23 .23 .31 .19 .13 .23 .31

M.e. of Lbs of Mg Per PpOc Per 100 Grams Acre of Soil 186.0 86.0 180.0 186.0 262.0 144.0 276.0

.67 *46 .29 .21 .25 .42 .42

M.e. of Ca Per 100 Grams cf Soil 7.35 6.98 2.11 1.79 1.49 0.64 5.02

93 Table III.

Effect of Methods and Rates of Seeding Clover, Oat Companion Crops and Insecticide Treatments on Seed Production of Red Clover

Cultural Treatment Mean Seed Yield in Bushels Per Acre Row width Rate of seeding Companion of clover clover in lbs. Crops Insecticide Treatment in inches Per Acre Benzene Untreated Hexachloride Toxaphene DDT Broadcast it

n » it it

ii »

n it

n »

7 inches it it

4 8 12

16 4 8 12 4

8

4 8 12

tt

4 8 12

ii

16

it

4 8 12

it

»

it

»

Neosho it it

»

None ii it it

Benton

Neosho it

«

4 8 12

None

h

« tt

n

4

.

1.85 2.29 3.00 2.36

1.63 2.30 2.49 2.60

2.55 2.09 1.61 2.63

1.83 2.01 2.75 2.39

2.76 2.31 2.44

2.34 2.09

2 .4 0

2.37

2.56 2.39 2.96 2.81

1.81 2.64 2.02 2.50

2.23 2.87 2.77 1.83

2.20 2.02 2.05 3.05

2.04 2.22 2 52

2.22

2.67 2.98 2.32 2.96

3.52 2.54 2.42 2.14

2.46 2.61 2.97 2.07

1.92 3.77

2.51 1.80 2.27 2.56

2.45 2.15 2.11 2.80

2.23 2.36 2.02 2.97

2.68 2.39 2.33 2.32

2.70 2.45 3.09 2.27

2.27 2.25 2.94 2.96

2.35 2.02

it

14 inches

16

2.4L 2 57 2.91 2.11

it

ii

«

1.30 2.08 2.45 1.69

2.66

16

n

1.58 1.89 2.55 1.61

»

it

h

3.27 1.93 2.10 2.29

2.04

Benton ii

16

1.82 1.72

1.72

it

12

16

ii

»

16

it

it

None »

it it it

Benton

8

ii

12

it

16

it

3.02 3.08 2.90 2.56

3.01 2.98

2.03 1.89 2.27 2.11

1.29 1.69 2.37

2.84 2.01 2.85 2.77

2.08 2.63

2.50

2.60 2.19

2.50

.

2.86

94 14 inches it it »

Cable IV.

4 a 12 16

Neosho h

it »

2.12 2.72 2.44 2.70

2.19 2. 56 2.30 3.31

2.06 2.54 2.35 2.82

1.62 2.68 2.96 2.23

Analysis of Variance for Methods and Rates of Seeding Clover, Oat Companion Crops, and Insecticide Treatmaits on Seed Production of Red Clover

Sig- . Degrees Variance nificance of Mean Ratio at the Source of Variation_________________ . ____ Freedom Square F 5% Pt. Main Plots : Methods Companion Crops Replications Companion Crops x Methods Companion Crops x Replications Methods x Replications Companion Crops x Methods x Replications Error (a) Subplots : Rates of Seeding Rates x Methods Rates x Companion Crops Rates x Companion Crops x Methods Rates x Replications Rates x Companion Crops x Replications Rates x Methods x Replications Rates x Companion Crops x Replications x Methods Error (b) Sub-Subplots: Insecticides Insecticides x Insecticides x Insecticides x Insecticides x x Methods Insecticides x Insecticides x Replications Insecticides x Insecticides x

Methods x Replications Rates x Replications

1.91 4.88 2.67 0.39

16

1.77

3 6 6 12

1.24 O.64 0.41 0.39

54

0.70

3 6 6 9

0.22 0.66 0.42 0.22

1.08 2.76 1.51 0.22

3.63 3.63 3.63 5.84

1.77 0.91 0.58 0.56

2.78 3.75 3.75 2.40

0.55 1.65 1.05 0.55

8.54 2.13 2.13 1.90

4 4 a

6 12 12 24

Methods Companion Crops Rates cf Seeding Rates x Companion Crops Replications Companion Crops x

2 2 2 4

36 6 12 12 18

95 Insecticides x Companion Crops x Methods Insecticides x Hates x Methods Insecticides x Rates x Companion Crops Insecticides x Comp* Crops x Methods x Replications Insecticides x Hates x Comp. Crops x Replications Insecticides x Rates x Methods x Replications Insecticides x Rates x Companion Crops x Replications x Methods Error (c)

12 Id 18 24 36 36 72 300 0,40

Total

Analysis of Variance for the Effect of Methods and Rates of Seed­ ing Clover Alone and With Oat Companion Crops on the Stands and Forage Yields of Red Clover

Source of Variation Main Plots : Methods Companion Crops Replications Companion Crops x Methods Companion Crops x Replications Methods x Replications Companion Crops x Methods x Replications Error (a)

Degrees of Freedom

Mean Square Stand Forage Yields 1947 1948 1947 1948

2 2 2 4

0.66* 0.06 0.01 0.37

12.45**0.1927 2.86 0.3180** 0.53 0.9643** 0.93 0.0853

0.7897* 0.1647 0.3101 0.0898

16

0.18

1.94

0.0873

0.1513

3 6 6 12

0.67** 0.23 0.14 0.37

2.07 0.0350 0.15 0.0110 0.64 0.0411 0.24 0.0166

0.1521 0.0150 0.0435 0.068?

0.14

0.99

0.0836

4 4 8

Subplots: Rates of Seeding Rates x Methods Rates x Companion Crops Rates x Companion Crops x Methods 6 Rates x Replications Rates x Companion Crops x 12 Replications 12 Rates x Methods x Replications Rates x Methods x Companion Crop x Replications 24 Error (b) Total * Significant at the 5 per cent point ^^Significant at the 1 per cent point

H O xn

Table V,

431

0.0197

96

Table VI.

Analysis of Variance for the Effect cf Methods and Rates cf Seeding Clover, and Oat Companion Crops on the Bloom of Red Clover

Source of Variation Main Plots: Methods Companion Crops Replications Companion Crops x Methods Companion Crops x Replications Methods x Replications Companion Crops x Methods x Replications Error (a) Subplots : Rates of Seeding Rates x ’Methods Rates x Companion Crops Rates x Companion Crops x Methods Rates x Replications Rates x Companion Crops x Replications Rates x Methods x Replications Rates x Methods x Companion Crops x Replications Error (b) Total * Significant at the 5 per cent point ■^^Significant at the 1 per cent point

Degrees of Freedom 2 2 2 4

Mean Square Bloom Ratings 8-4-47 8—11—47 8—28—47 1.36 1.14 38.86** 64.73** 8.52 5.17 0.98 0.89

1.18 37.40** 2.90 2.46

4 4 8 16

1.04

2.12

1.40

3 6 6 12

2.05** 0.26 1.57** 0.14

3.43** 0.17 2.68** 0.12

1.62* 0.97 1.20 0.60

54

0.35

0.51

0.55

6 12 12 24 107

97

Table VII*

Analysis of Variance for the Effect of Methods and Rates of Seeding Clover, and Oat Companion Crops on the Bloom, of Red Clover

Source of Variation Main Plots ï Methods Companion Crops Replications Companion Crops x Methods Companion Crops x Replications Methods x Replications Companion Crops x Methods x Replications Error (a)

Degrees of Freedom

6-3

Mean Square 1948 Bloom Ratings 6-8 6-30 7-13 7-20

2 2.40* 1.67 0.70 0.06 0.77 2 1.01 1.23 0.34 0.92 0.02 2 1.67 3.59 0.15 3.01**2.58** 4 1.06 1.45 0.10 1.26 0.22 4 4 8

Subplots: Rates of Seeding Rates x Methods Rates x Companion Crops Rates x Companion Crops x Methods 6 Rates x Replications Rates x Companion Crops x 12 Replications 12 Rates x Methods x Replications Rates x Methods x Companion Crops x Replications 24 Error (b) Total insignificant at the 5 per cent point ^significant at the 1 per cent point

16

0.48

1.48

0.40

0.43

0.34

3 0.70 2.13**0.31 6 0.71 0.17 0.30 6 0.55 0.69 0.28 12 0.24 0.39 0.10

0.25 0.71 0.06 0.36

0.18 0.32 0.05 0.35

54 0.35

0.24

0.19

107

0.46

0.22

98 BIBLIOGRAPHY AND CITED REFERENCES 1*

Albrecht, H. R. Vetch varieties for soil improvement and seedproduction in Alabama, Alabama Agr. Exp. Sta, Bui. 253. 1942.

2.

Albrecht, W. A. Red clover suggests shortage of potash. Plant Food, 29:21 August 1945e

3*

Better Crops with

« KLemme, A. W., and Mierke, W* Potassium, helps put more nitrogen into sweet clover. Jour. Amer. Soc. Agron., 40:1106-1109• 1948.

4e

Alston, D. Red clover for seed. Jour. Min. Agr., (New Zealand) 51:347-348. 1944.

5*

Bartholomew, R, P. The rate of absorption of potassium by plants and its possible effect upon the amount of potassium remaining the soil from the application of potassium fertilizers. Arkansas Agr. Exp. Sta* Bui. 265. 1931.

6.

Beard, D. F., and Dunham, TJ. E. Honeybees increase clover seed production 15 times. Ohio Ext. Bui. 253• 1945.

7.

Blinn, P. K. Factors that affect alfalfa seed yields. Colorado Agr. Exp* Sta. Bui. 257. 1920.

8.

Brown, B. A., Mims ell, R. I., and King, A. V . Potassium and boron fertili­ zation of alfalfa on a few Connecticut soils. Soil Sci. Soc. Amer. Froc., 10:134-140. 1946.

9.

Bushnell, T. M. The story of Indiana soil. Purdue Agr. Exp, Sta. Cire. 1* 1944.

10.

Carlson, J. ¥. Alfalfa seed investigations in Utah. Utah Agr. Exp. Sta. Bui. 258. 1935.

11.

Carolus, R. L. Effect of certain ions, used singly and in combination, on the growth and potassium, calcium, and magnesium absorption of the bean plant. Plant Physiol., 13$349-363• 1938•

12.

Chandler, R. P., Peech, M., and Brgidfield, R. The influence of muriate of potash and borax on the yield, deficiency symptoms and potassium content of plant and soil. Soil Sci. Soc, Amer. Proc., 10:141—145* 1945.

13.

Collister, E. H. Factors affecting stands and development of red clover. Master1s Thesis Purdue University Library, Lafayette, Indiana. 1948.

14.

Cook, R. L., and Millar, C. E. Some soil factors affecting boron avail­ ability. Soil Sci. Soc. Amer. Proc., 4:297-301. 1940.

15.

Cox, J. P., and Megee, C. R. The clovers and clover seed production in Michigan. Michigan Agr. Exp. Sta. Bui. 130. 1924.

99 X6*

Dawson, J«S«, and Gustafson, A. F. Influence of borax on deficiency symptoms and the boron content of the plant and soil. Soil Sci. Soc* Amer. Proc., 10:147-149. 1946.

17#

Davis, R. L., and Wilson, M. C. The effects of insects, insecticides, and cultural practices on the quality and quantity of forage and seed yields of alfalfa. Purdue Agr. Exp. Sta. Ann. Rept. 1949#

18.

Davis, R. R. The reaction of four strains of Agrostis Pajustris to various levels of nitrogen, phosphorus, potassium, and calcium. Master1s Thesis Purdue University Library, Lafayette, Indiana. 1949*

19*

Dregne, H. E., and Powers, ¥. L. Boron fertilization of alfalfa and other legumes in Oregon. Jour. Amer. Soc. Agron., 34:902-912. 1942.

20*

Dmitriev, K. A. Use of boron as a clover manure in seed production. Herbage Abstracts, 8:181. 1938.

21.

Eaton, F. M. Interrelations in the effects of boron and indoleacetic acid on plant growth. Bot. Gaz., 101:700-70$. 1940.

22* Garrison, C. S. Better strains of Cire. 419. 1942.

red clover. New Jersey Agr. Exp. Sta.

23.

Gericke, W. F. Certain relations between root development and tilleri%% in wheat; significance in the production of high-protein wheat. Amer. Jour. Bot., 9:366-369. 1922.

24*

Goesard, H. A. Important clover insects. Ohio Agr. Exp. Sta. Mo. Bui. 4*

.

1918

2$. Grandfield, C. 0. Alfalfa seed production as affected by organic reserves, air temperature, humidity, and soil moisture. Jour. Agr. Res., 70:123-132. 1945. 26. Grizzard, A. L*, and Matthews, E. M. The effect of boron on seedpro­ duction of alfalfa. Jour. Amer. Soc. Agron. 34:365-368. 1942. 27. Harper, H. J* Wide row spacing and row application of limestone and phosphate for sweet clover production. Oklahoma Agr. Exp. Sta. Bui. B-248. 1941. 28.

____________ Effect of row spacing on the yield of small grain nurse crops. Jour. Amer. Soc. Agron., 38:785-794* 1946.

29* Harrison, C. M. Responses of Kentucky blue grass to variations in tempera­ ture, li^ht, cutting, and fertilizing. Plant Physiol., 9:83-106. 1934* 30*

Hollowell, E. A. Influence of atmospheric and soil moisture upon seed setting in red clover. Jour. Agr. Res., 39:229-247. 1929•

31.

Hollowell, E. A., and Heusinkveld, D. The effect of rate of planting on yields of adapted and unadapted red clover. Jour. Amer. Soc. Agron., 33:569-571. 1941.

100 32»

Hutcheson, T» B., and Cocke, R. P. Effects ofboron on the yield and duration of alfalfa. Virginia Agr. Exp. Sta. Bui. 336. 1941-

33*

Jackson, M. L., Evans, C. E., Attoe, 0. J., Huber, J. L., and Kaudy, J• C» Soil fertility level in relation to mineral and botanical com­ position of forage. Soil Sci. Soc. Amer. Proc., 12:282-289. 1947.

34*

Jewett, H. H. Leafhopper injury to clover and alfalfa. Kentucky Agr. Exp'. Sta. Bui. 293. 1929.

35*

Johnston, E. S., and Dore, W. H. Influence of boron on chemical compo­ sition and growth of tomato plants. Plant Physiol., 4:31-62. 1929.

36.

Jones, H. E., and Scars et h. G* D. The cal cium-bor on balance in plants as related to boron needs. Soil Sci., 57:15-24. 1944.

37 * Kelley, W. P. A review of researches on nitrogen fertilization in re­ lation to economic crop production with special reference to future investigations. Jour. Amer. Soc. Agron., 25:51-64. 193338.

Knowles, F., vfalkin, J. E., and Cowie, G. A. Some effects of fertilizer interactions on the growth and composition of the potato plant. Jour. Agr. Sci., 30:159-181. 1940.

39*

Kozlova, Z. I. Manuring of clover in the non-black earth belt Herbage Abstracts 17:21. 1947*

40.

Kramer, H. H. and Davis, R. L. The effect cf stand and moisture content on computed yields of alfalfa. Jour. Amer. Soc. Agron., 41:470-473• 1949#

41.

Kraus, E. J., and Kraybill, H. R. Vegetation and reproduction with special reference to the tomatoe. Oregon Agr. Exp. Sta. Bui. 149* 1918*

42.

Ladygin, I. ya. Manuring of forage crops. Soils and Fert. Abs., 1:208. 1938.

43.

Larkin, R. A. Soil factors affecting the nutritive value of alfalfa. Jour* Amer. Soc. Agron., 40:1132. 1948*

44.

Lucas, R. E., Scarseth, G. D., and Sieling, D. H. Soil fertility level as it influences plant nutrient composition and consumption. Purdue Agr. Exp. Sta. Bui. 468. 1942.

45*

Madhok, M. R. Association of legumes and non-legumes. Soil Sci., 49: 419-413. 1940.

46»

Mann, H. H. Investigations on clover sickness. Jour. Agr. Sci., 28:435455. 1938.

47.

McClymonds, A. E., and Hulber, H. W. Growing clover seed in Idaho. Idaho Agr. Exp. Sta. Bui. 148. 1927*

48.

Mehlich, A., and Reed, J. F. Effect of cation-exchange properties of soil on the cation content of plants. Soil Sell, 66:289-305. 1948 »

of U.S.S.R*

101 49.

Mercer, R. D. Alfalfa seed production. Montana Agr. Exp. Bui. 175 • 1939.

50.

Midglesy*, A. R. Effects of lime and organic matter on boron fixation and availability in soils, Vermont Agr. Exp. Sta. Bui. 495. 1942.

51#

Moore, R. A., and Delwiche, E. J. Growing clover for seed and forage in northern Wisconsin. Wisconsin Agr. Exp. Sta. Bui. 183. 1909.

52.

Muhr, G. R. Plant symptoms of boron deficiency and the effects of borax on the yield and chemical composition of several crops. Soil Sci 54* 55-65. 1942.

53*

Naftel, J. A. Response of crimson clover to boron with and without lime on Coastal Plains soils. Jour. Amer. Soc. Agron., 34:975-905. 1942.

54#

Olson, L. C. Fertilizing to increase the yield and longevity of alfalfa in Georgia. Ams*. Fert., 101:28-30. 1944.

55#

Pieters, A. J. Red Clover culture. U.S.D.À. Farmers Bui. 1339* 1923#

56*

Piland, J. R., Ireland, C. F., and Reisenauer, H. M. The importance of borax in legume seed production in the South. Soil Sci., 57:75-84• 1944.

57*

Poehlman, J. M. Growing good crops of oats in Missouri. Missouri Agr. Exp. Sta. Bui. 439. 1942.

58. Powers,W. L. Boron as a fertilizer for western Oregon soils. Sci., 90: 36-37. 1939# 59*

___________ Boron, a minor plant nutrient of major importance. Better Crops with Plant Food, 25:6. 1941*

60. Prince, A. L*, Zimmerman, M., and Bear, F. E. The magnesium-supplying power of twenty New Jersey soils. Soil Sci., 63:69-78. 1947• 61. Prince, F. S. Potash extends the life of clover stands. Better Crops with Plant Food, 26:17-19. May 1942.

62. Reeve, E., and Shive, J. W. Pot assium-boron and calcium-bor on relation­ ships in plant nutrition. Soil Sci., 57:1-14. 1944* 63. Rogers, H. T. Response and tolerance cf various legumes to borax and critical levels of boron in soils and plants. Jour. Amer. Soc. Agron., 39:897-928. 1947* 64. Schwardt, H. H., Newsom, L. D., and Norton, L. B. Increasing red clover yields by treatment with DDT or hexachlorocyclohexane. Jour. Econ. Enton., 40:363-365* 1947* 65. Smith, D., and Graber, L. F. The influence of top growth removal on the root and vegetative development of biennial sweet clover. Jour. Amer. Soc. Agron., 40:730-743• 1948.

102 66e Snider, H. J. Soil requirements for red clover* Plant Food, 30:17-19. November, 1946.

Better Crops with

6?#

Sommer, A* L., and Sorokin, H. Effects of the absence of boron and of some other essential elements on the cell and tissue structure of the root tips of Pisurn sativum* Plant Physiol., 3:237-260. 1928.

68.

___________ , Wear, J. I., and Baxter, A. The response to magnesium of six different crops on sixteen Alabama soils. Soil Sci. Amer. Proc., 5* 205-212. 1940.

69.

Staple don, R. G. Herbage seed production in New Zealand: red clover and lucerne. Jour. Min. Agr., 34:328-332. 1927.

70.

Starring, G. C. Influence of the carbohydrate-nitrate content of cuttings upon the production of roots. Proc. Amer. Soc. Hort. Sci., 20:288-292. 1923.

71*

Tharp, W. E., and Fowler, E. D. Soil survey of Kosciusko County, Indiana. U.S.D.A. 1927.

72.

Truog, E., Goates, R. J* Gerloff, G. C., and Berger, K. C. Magnesiumphosphorus relationships in plant nutrition. Soil Sci., 63:19-27* 1947.

73*

Tysdal, H. M. Influence of tripping, soil moisture, plant spacing, and lodging on alfalfa seed production. Jour. Amer. Soc. Agron., 38:515-535* 1946.

74*

U.S.D.A. Agricultural statistics, 1948. Washington, D. C. U. S. Government Printing Office. 1949*

75.

Van Itallie, T. B. Cation equilibria in plants in relation to the soil. Soil Sci., 46:175-186. 1938.

76. Virtanen, A. I. The nutrition of plants. Herbage Rev., 1:88-91* 1933* 77* Watson, S. J. The manuring of grasses and clover. Farming, 3 1110-113* 1949. 78.

Westgate, J. M. Crimson clover seed production. U.S.D.A. Farmer's Bui. 1411. 1924*

79.

Williamson, R. M. Climatological data, Indiana section, U. S. Dept, of Commerce, Weather Bureau, 3-5: Nos. 4> 5, 6, 7, and 8. 1947—1949*

80. Milliard, C. J., Thatcher, L. E., and Cutter, J. S. Alfalfa in Ohio. Ohio Agr. Exp. Sta. Bui. 540. 1934* 81.

Willis, L. G., and Piland, J. R. A response of alfalfa to borax. Jour. Amer. Soc. Agron., 30:63-67* 1938»

82.

Wilsie, C. P. Seed production studies with legumes in Hawaii. Amer. Soc. Agron., 27:734-790. 1927.

103 83»

, _______Producing alfalfa and red clover seed in Iowa# Jour. Amer. Soc# Agron., 41:545-550. 1949#

84#

, and Hollowell, E. A. Effect of time of cutting red red clover on forage yields, seed setting and chemical composition# Iowa Agr. Exp. Sta. Res. Bui. 357. 1948*

85*

Wilson, M. C. Organic insecticides to control alfalfa insects. Jour* Econ. Entom., 42: (3 ) 496-499# 1949.

86.

Wilson, P. W* The biochemistry of symbiotic nitrogen fixation. University of Wisconsin Press, Madison. 1940*

87*

Wright, L. E., Pelletier, J. R., and Ripley, P. 0. Soil fertility studies. Sci. Agr., 29:128-136. 1949#

The

VITA Earl Harold Collister was born in Galva, Illinois on March 25, 1923#

He obtained his early education in country schools near GaTva,

and graduated from Galva Community High School, Galva, Illinois, in June, 1941.

In September of that year he enrolled in the College of

Agriculture at the University of Illinois where he studied two years before enlisting in the U. S. Marine Corps.

After separation from the

service in November, 1945> he enrolled in the College of Agriculture at Purdue University and received the degree of Bachelor of Science in Agriculture in February, 1947#

He entered the Graduate School at Purdue

University in February, 1947 and worked as a Research Fellow on factors affecting seed production in red clover*

While employed at Purdue he

received the degree of Master of Science in June, 1948.

The subject of

his dissertation was "Factors affecting stands and development of red clover. Trifolium pratense L."

Following graduation from Purdue he will

join the staff of the Texas Research Foundation at Renner, Texas as Associate Agronomist*