A study of the chemical and physical changes produced in a soil by the formation of the organic colloidial complex

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A STODT (V SHE CHHilCAL AND PHYSICAL CHAHG2S PHODUCED IN A SOU BT THE FOBMAIION OP THE OEGAHIC COLLOIDAl COJPIM

Carl Williams K elley

Thesis subm itted to the F acu lty o f th e Graduate School o f th e U n iv ersity o f Maryland in p a r t i a l f u lf illm e n t o f the requirem ents f o r the degree o f Doctor o f Philosophy

UMI Number: DP70186

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The w rite r expresses h i s a p p re cia tio n to Dr* R* P . Thomas, P ro fe ss o r o f S o ils , who suggested t h is problem and d ire c te d th e research* He i s also g ra te fu l f o r the many valu ab le suggestions given by Dr* M* S* Anderson, A s s is ta n t C hief, Chemistry and Physics D iv isio n , Bureau o f P la n t In d u stry , U nited S ta te s Department o f A g ric u ltu re .

LIST OP TABLES Table 1. 2

.

3.

T itle Organic M atter Content o f 10 Maryland s o i l s as Determined lay Various Methods* ....................

Page . ...

l6

The Exchange C apacity, Percentage o f Organic M atter and pH Values f o r th e 10 Maryland S o i l s . . . * . . . . . . ......................... 17 The E ffe c t o f Organic M a te ria ls, Lime, and F e r t i l i z e r on the pH Value, Organic M atter and. Exchange C apacity o f B e lts v ille s i l t loam S o i l . . . . ...........................................

k.

The Value Obtained by D ividing the M illie q u iv a le n t o f the Organic Exchange C apacity by th e P ercent o f Organic M atter Secured w ith th e D iffe re n t Methods o f D eterm inations on the 10 Maryland S o i l s ................. . . . » 19

5*

The E ffe c ts o f S o il Treatments on the Organic Exchange Capacity* o f a S o il ...........................................

IS

20

TABLE 01 CONSENTS

Page

INTRODUCTION

.....................................................................................1

REVIEW OF LITERATURE........................................................................................... 2 PROCEDURE. , , . #........................................................................................................ 7 DISCUSSION..................................

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SUMMARY......................................................................................................................21 BIBLIOGHAPHT............................................................................................................ 22

INTRODUCTION I t has long heen known th a t organic m atte r p la y s an im portant p a r t in s o il f e r t i l i t y . standpoints*

I t serves to improve s o ils from se v e ra l

Among th ese a re improved w ater holding power, "bio­

lo g ic a l c o n d itio n s, cap acity to hold p la n t n u tr ie n ts and in o th e r ways improve s o il a s a medium f o r p la n t growth. The a b i l i t y to hold p la n t n u tr ie n ts and to d e liv e r these n u tr ie n ts to growing p la n ts i s c lo s e ly a sso c ia te d w ith the p ro p e rty of base exchange*

Since base exchange p la y s such a prominent p a r t in s o il

economy, much emphasis has been p laced on t h is to p ic by s o il in v e s ti­ g a to rs during th e l a s t two decades*

The general fe a tu re s o f th e ex­

change p ro p e rtie s have long been known, but the in te n s if ie d re se a rc h o f recen t y e a rs has added much to the p r a c tic a l in te r p r e ta tio n s o f th e p ro cesses involved. In view o f th e g re a t importance attach ed to s o il organic m atter in g en eral and to th a t en terin g in to base exchange cap acity in p a r t i c u l a r , t h i s in v e s tig a tio n was undertaken. in v o lv es two im portant f a c to r s .

The in v e s tig a tio n

One, a comparison o f d if f e r e n t

methods fo r the determ ination o f organic m atter th a t e n te rs in to th e exchange c a p a c ity .

The o th e r, a study o f base exchange in s o il

as a ffe c te d by the presence o f organic m a tte r.

REVIEW 02* LITERATURE The bodies o f dead organisms (30) and th e re sid u es o f liv in g m a tte r dep o sited on and w ith in th e s o il form th e m a te ria l known as s o il organic m a tte r.

S oil organic m atter th e o r e tic a lly com prises

o n ly th e dead re sid u e o f organisms and the v a rio u s products o f t h e i r decom position.

I t i s p r a c tic a lly im possible, however, to sep arate

t h i s m a te ria l from th e liv in g m icro-organism s th a t l iv e in th e s o il and c a rry on th e ta s k o f decomposing the re s id u e s .

The hulk o f the

bodies o f m icro-organism s, to g e th e r w ith t h e i r own re sid u e s, i s th e re fo re regarded as a p a r t o f s o il organic m a tte r. Chemically, s o il organic m atter comprises a m ixture o f a g re a t many substances th a t may be c l a s s i f i e d in to th re e groups;

( l ) c a r­

bohydrates, ( 2) p ro te in s , ( 3) lig n in , and (ty) f a t s , r e s in s , waxes and sim ila r compounds. The term ’'humus* (20) i s sometimes used to d esig n ate s o il organic m a tte r.

"Humus" i s a mme given to a group o f black, s tic k y , o r

waxy, complex compounds th a t a re derived from organic m a tte r o r i g i ­ n a tin g from substances th a t the p la n ts have sy n th esized . Much o f th e m a te ria l th a t c o n s titu te s humus i s derived from lig n in o f p la n t re s id u e s .

I t has been found th a t lig n in and lig n in -

l i k e substances have base exchange p r o p e r tie s . McGeorge (6) has shown th a t th e exchange c ap a city o f organic m a tte r i s in l a r g e s t p a r t due to lig n eo u s compounds, and th a t lig n in p o ssesse s a chem ically eq u iv alen t exchange p ro p e rty . i t s e l f , he

As f o r lig n in

says th a t th e exchange c ap a city depends upon the methods

used in p rep a rin g o r se p a ra tin g i t from th e mother substance, and th a t

3

i t may fee su b je c t to f u r th e r in c re a s e in exchange c a p a c ity by h y d ro ly sis o r f r a c tio n a tio n .

(The theoxy i s advanced t h a t a p r o td n lin k a g e i s

in most p a r t re sp o n sib le f o r th e exchange p ro p e rty o f lig n e ru s m a te ria l. M uller (9) has proved th a t th e re i s an in c re a s e i n base exchange c a p a c ity o f organic m a tte r w ith decom position. M ille r, Smith and Brown (8) in carxying o u t base exchange stu d ie s on o a t straw , wheat straw , e tc . found th a t w ith decom position o f th ese m a te ria ls th e re was an in c re a se i n base exchange c ap a city , although the in c re a se was no t i n th e same r e la tio n to one an o th er.

Also they found

th a t mature p la n ts d i f f e r g r e a tly i n base exchange c a p a c ity . Meyer (7) in exchange c ap a city stu d ie s on mixed o rg an ic-in o rg an ic systems determ ined t h a t th e r e s u ltin g m ixture in every case had a low er exchange c a p a c ity than th e sum o f th e in d iv id u a l exchange c a p a c itie s . In c o n sid e ra tio n o f th e im portant p a r t played by organic m a tte r in base exchange p ro c e ss, i t seems th a t in v e s tig a tio n s d e a lin g w ith t h i s phenomena would be more p r o f i ta b le .

P o ssib ly th e reason i s the

la c k o f a d e f i n i te method f o r making such d eterm in atio n s.

The few

d eterm inations o f th e organic base exchange cap a city have been made in one of th e fo llow ing ways (12): (a) th e organic p o rtio n o f th e s o il i s removed by an a lk a lin e e x tra c tin g so lu tio n and re p re c ip ita te d by th e a d d itio n o f a m ineral acid , and th e determ ination o f the base ex­ change c ap a city o f th e organic m atter i s made d ir e c tly ; (b) the organic m atter o f th e s o il i s destroyed by g e n tle ig n itio n , and the base ex­ change c ap a city i s determ ined b efo re and a f t e r treatm en t, th e d iffe re n c e re p re se n tin g the exchange c ap a city o f the organic m atter; (c)

th e

o rg an ic m a tte r o f th e s o il i s destroyed by treatm ent w ith hydrogen p ero x id e, and th e base exchange c ap a city i s determ ined as in (b ).

k

In any o f th e foregoing p rocedures, se rio u s o b je c tio n s may a r i s e . The c h ie f o b je c tio n to (a) i s th a t t h is procedure re q u ire s co n sid erab le tim e.

A lso, th e exchange capacity* o f th e organic m atte r depends upon

th e method used i n p re p a rin g o r se p a ra tin g i t from th e mother substance. In (b) th e re i s a se rio u s th r e a t o f dehydrating th e s o il m inerals by ig n itio n and th u s reducing th e base exchange c a p a c ity o f th e in ­ organic complex.

A second se rio u s th r e a t to t h i s procedure i s th a t

7 o r 8 hours o f i g n itio n a re re q u ire d to b rin g about th e d e s tru c tio n o f th e organic m a tte r. In (c) th e re i s a p o s s i b i l i t y th a t th e peroxide treatm ent m ight a f f e c t the inorganic base exchange capacity* in a manner s im ila r to th a t o f ig n itio n .

UcGeorge (6) , however, showed th a t d ig e s tio n w ith

E 0 does n o t a f f e c t th e exchange c ap a city o f sy n th e tic z e o lite s . The 2 2 p r in c ip a l o b je c tio n to the use o f t h i s procedure i s th e in co n sisten cy in th e manner in which the o x id atio n s have been c a rrie d o u t.

A lso,

th e re i s a la c k o f d e f in ite inform ation concerning the e f f e c ts o f v a rio u s co n ce n tra tio n s o f peroxide in making such d eterm in atio n s. Sroadfoot and Tyner ( 3) p o in t ou t th a t the exchange cap acity o f org an ic re sid u e s v a rie s w ith th e c a tio n used f o r s a tu ra tio n o f th e ex­ change complex*

For in sta n c e , th e ab so rp tiv e c ap a city f o r ammonium was

found i n a l l cases to be considerably le s s than th a t f o r the d iv a le n t c a tio n s . B a r t l e t t , Buble and Thomas (2) found, in using the hydrogen p e r­ oxide method o f determ ining organic exchange cap acity , th a t t h is reagent in c re a s e d th e in o rg an ic exchange c ap acity in some o f the s o i l s . Base exchange, (10) whether organic o r in o rg an ic, i s a p ro p erty

5

o f s o i l 8 th a t has very im portant p r a c t ic a l a p p lic a tio n s .

When a

sim ple s a l t , such a s XCl, i s added to a s o i l , some potassium changes p la c e s in th e c o llo id a l p a r t i c l e w ith calcium , sodium and o th e r m ineral h ase elem ents, and th e se in tu rn e n te r in to th e s o il s o lu tio n .

The

r e s u l t i s th a t only a p a r t o f th e potassium which was added i n solrutio n rem ains w ater so lu b le . "Base exchange capacity" i s a term th a t i s used to denote th e measure o f th e r e l a ti v e a b i l i t y o f a s o il to r e ta in b a sic elem ents. "Exchangeable c atio n s" would p o s s ib ly be a b e tt e r term, f o r th e n hydrogen which a lso p la y s an im portant p a r t in base exchange re a c tio n s would be in clu d ed . Ion exchange (base exchange) (19) may be defined as a re v e rs ib le in terch an g e o f io n s between a liq u id phase and a s o lid body which does not involve any ra d ic a l change in th e s o lid s tru c tu r e . observed in s o il by Way in lS^O.

I t was f i r s t

He passed a so lu tio n o f KOI through

a bed o f s o i l , and found th a t a l l th e potassium was removed from the so lu tio n and rep la ce d by an eq u iv alen t amount o f calcium and sodium from th e s o i l . Gedroiz and H issin k (20) have shown th a t base exchange obeys th e chemical law o f mass a c tio n and eq u ilib riu m . th e law

According to Gedroiz,

o f s o il base exchange may be s ta te d as follow s:

"Absorbed

io n s of s o il conpounds a re d isp lac ed by o th e r io n s in equivalent r a t i o ." Only a lim ite d q u a n tity o f an exchangeable b a sic element o f a s o i l m a te ria l can be brought in to so lu tio n by th e sin g le a d d itio n o f a d isp la c in g agent; but under lea ch in g co n d itio n s, the displacem ent

6

can f i n a l l y toe made complete, as G-edroiz and H issin k have shown* Prom th e fo regoing review o f l i t e r a t u r e i t can toe seen th a t th e methods used f o r th e determ ination o f organic m atter a s w ell a s those used f o r determ ining th e organic m atter th a t e n te rs in to th e exchange complex a re f a r from s a tis fa c to ry *

I t i s hoped th a t

th e m a te ria l p re se n te d in th e follow ing pages may throw a l i t t l e more l i g i t on th e problem*

PROCEDURE A survey was made on te n re p re s e n ta tiv e Maryland s o ils ( 5 ) f o r org an ic and in o rg an ic base exchange capacity*

These s o ils were

used because they v a rie d i n organic m atte r content and genealogy.

It

was thought th a t r e s u l t s obtained from th ese treatm en ts m ight be a p p lic a b le to Maryland s o ils in g e n e ra l.

A lso, th ese s o ils were

su b jected to d eterm inations f o r t o t a l organic m a tte r as w ell as the f r a c tio n o f organic m a tte r th a t i s re a d ily o x id lz a b le .

Samples o f

one s o il were brought in to th e greenhouse and allowed to incu b ate w ith v a rio u s treatm en ts o f organic m a tte r, lim e and f e r t i l i z e r *

Base

exchange c ap a city and organic m a tte r e x tra c tio n s were determ ined on th ese so ils* For th e base exchange a n a ly s is , th e lea ch in g method o f Schollehberger and D re ib e lb is (13) was used w ith s lig h t m o d ifica tio n s fo r th e s o ils which were e x tra c te d w ith barium acetate* was a d ju ste d to 7*0.

The pE of t h i s so lu tio n

In t h i s method, ten grams o f s o il were w eigied

o ut and tra n s fe rre d to a leach in g tube*

Eowever, in s te a d o f using

tubes having a p e rfo ra te d p o rc e la in d is c covered by a f i l t e r paper, le a c h in g tubes w ith s in te re d g la s s d is c s were employed. le a c h in g p ro cess co n sid erab ly .

These speeded up the

A rubber policeman was p laced on th e

stem o f th e lea ch in g tubes so th a t th e s o il might soak in th e 150 m .l. o f leach in g s o lu tio n over n i ^ i t .

In th e morning the policeman was re ­

moved and th e so lu tio n allowed to le a c h th ro u ^ i th e s o i l s .

Then the

leached s o ils were washed w ith successive p o rtio n s of d i s t i l l e d w ater u n t i l the washings showed no t e s t s f o r barium ions w ith d ilu te H^SO^* R in e ty -fiv e p e rc e n t alcohol was used in one o r two small p o rtio n s f o r

s

le a c h in g in o rd er to decrease hydrolysis*

The washed s o i l s were next

leach ed w ith 150 m.l* o f one normal potassium so lu tio n in order to d is ­ p la c e a l l o f th e ‘barium io n s p re se n t in th e exchange complex.

The d is ­

p lac ed barium was determ ined by u sing a s lig h t m o dification o f th e method recommended by S cott (lit*). The base exchange c a p a c ity was determ ined before and a f t e r oxida­ tio n o f th e s o i l s .

(For r e s u lts see Table 2 ).

The o x id atio n was

accomplished w ith hydrogen p eroxide, u sing s ix treatm en ts o f twentyf iv e m .l. o f s ix p e rc e n t hydrogen p e ro x id e .

Each p o rtio n was allowed

to rem ain on t h e s o il over n ig h t and then d rained o f f th e fo llo w in g morning by removing th e policeman from th e stem o f th e tu b e. A pH determ ination was made on ®ch o f th e s o i l s by means o f th e Beckman pH m eter. Organic m a tte r determ inations were made on th e s o i l s b e fo re and a f t e r o x id a tio n , u sin g th e wet method f o r t o t a l carbon ( l ) .

This

method involves th e o x id atio n o f organic m a tte r w ith a chromie-phosp h o ric -su lp h n ric a c id m ixture and th e absorption o f th e carbon dioxide in standard sodium hydroxide. Bine d if f e r e n t methods f o r determ ining organic m atter were used on th e ten s o i l s . (ll)•

The h ypoiodite method used was th a t o f Norman and Feevy

In th is a n a ly s is f iv e grams o f s o il a re used, w ater added, and

io d in e and sodium hydroxide p laced in the b o ttle to form NaOI.

At

in te r v a ls p o rtio n s are withdrawn, HC1 added, th e io d in e t i t r a t e d w ith Na S J0_. For the ammonia e x tra c tio n method, a m o d ificatio n o f the 2 2 3 method o f Cameroh and B reazeale (H) was c a rrie d o u t. In ste ad o f u sing a yf> ammonia so lu tio n , as in the method above, th e s o il was shaken w ith a 10$ ammonia s o lu tio n , c e a tifu g e d , , the c le a r e x tra c t poured o f f and

9

evaporated to dryness on the h o t p l a t e .

The resid u e was taken up

w ith a l i t t l e d i s t i l l e d w ater and d ilu te H SO, , and t o t a l carbon 2 V determ ined. The bleaching powder method made use o f was th a t o f Treadwell and H all (17)*

Here f iv e grams o f s o il were placed in an

ev ap orating d ish along w ith th e b leach in g powder.

This was made by

weighing o u t 5 grams, adding w ater to make 500 m .l. and then tak in g out a 20 e .c . a liq u o t.

Ten p e rc en t El and 1 - 1 HC1 were added

and th e t i t r a t i o n made w ith HagSgO^. in th e KMnO^ method (1 7 ).

Three grams o f s o il were used

Twenty m .l. o f .1093 N KMnO^ were used

and the excess permanganate t i t r a t e d w ith Mohr1s S a lt; o rth o $ h « n an th ro lin e was used as an in d ic a to r . in th e C eric Sulphate Method o f a n a ly s is . in ch t e s t tube w ith 10 m .l. o f

This was p u t in an 8

H C eric Sulphate and heated in

a b o ilin g w ater b a th f o r 15 m inutes. was t i t r a t e d w ith Mohr* s S a lt.

One gram of s o il was used

The excess Ceric Sulphate

A blank run was made a t the same tim e.

The W alkley-Black Method ( l 8) makes use o f only one h a lf gram o f s o il.

T his i s mixed w ith 10 m .l. o f Ha Or 0

2 2 7

and 20 m .l. o f con-

c e n tra te d H SO, and heated in a ho t w ater b a th f o r 15 m inutes. Hie 2 If m ixture i s cooled, d ilu te d , 5 m .l. o f H^PO^ added and t i t r a t e d w ith Mohr* s S a lt.

This i s a m o d ifica tio n o f th e o r ig in a l method.

There

i s much s im ila r ity between th e Thomas-Wiliiams method ( l 6) and th e Walkl ey-Black method.

In th e form er 3 grams o f s o il a re o x id ised

w ith Hs^r^O^ and H^SO^, cooled, d ilu te d and an a liq u o t t i t r a t e d w ith Mohr* s S a lt.

N eith er th e S u lfato C erate nor th e P e rch lo ra te

C erate methods (15) have been used before in s o il work, but were esployed as d escrib ed f o r th e determ ination o f g ly c e ro l.

In th e

f i r s t method, (NH^ )2 Ce ( ^ 3)^ " a s d isso lv ed in 0 .5 m olar HgSO^

added to 1 gram s o i l and h eated on the w ater "bath fo r 15 minutes# s a l t was used f o r t it r a t i o n #

Mohr1s

The second method i s very much l ik e the

f i r s t , except th a t approxim ately 35$ HC10. i s used in ste a d o f th e H SO • 4 2 If Sodium o x a la te i s used to t i t r a t e th e excess o x id isin g agent# In both o f th ese methods barium diphenylamine su lfo n a te was used and found to be p re fe ra b le to any o th e r in d ic a to r used so f a r . For a l l the d eterm inations the f i n a l c a lc u la tio n was made to give th e answer i n term s o f p ercen t carbon.

This was m u ltip lie d by the

f a c to r 1.724 (4) f o r conversion to percentage organic m a tte r. The samples o f B e lts v ilie s i l t loam were c o lle c te d from th e f i r s t 6 inches o f s o i l , brought in and well mixed.

T h irty -fo u r, two g allo n

p o ts were s e t up, thus giving 17 treatm en ts and checks# given treatm en ts as shown in Table 3*

Each p o t was

®he dry organic m a tte r, c o n sistin g

o f wheat straw and soybean straw was added a t the r a te o f 10 grams p e r kilogram o f s o i l , o r 10 tons p e r acre#

The green organic m a tte r used,

green wheat and green a l f a l f a , were added a t th e r a te o f 20 grams p e r kilogram o f s o i l , o r 20 tons p e r aere# 40-50$ CaO and 9-10$ MgO.

The lim e added was b u rn t lim e,

A 10-6-1; f e r t i l i z e r was used.

I t as a

n e u tra l m ixture, made up o f Uramon, 50$ m uriate o f p o tash and 20$ superphosphate, and a p p lied a t th e r a te o f \ gram p e r kilogram o r J t« n p e r acre*

Also used were 5 p o ts f i l l e d w ith sand and tre a te d

w ith th e sane q u a n titie s as given above. w ith s o il b a c te r ia .

Each p o ta was in o cu late d

The dry organic m a te ria l was ground in a Braun

M ill, w hile th e green m a teria l was ground in a Mixablend G rinder co n tain in g w ater.

M oisture determ inations were made on the s o il by

means o f th e H ilgarde Otq>s and the p o ts k ep t a t optimum m oisture hy adding d i s t i l l e d w ater a t in te r v a ls ,

Every two o r th re e weeks the

11

c o n te n ts o f th e p o t a were screened, and w ell mixed.

The in cu b atio n

was c a r r ie d on f o r approxim ately 300 days, a t the end o f which the c o n te n ts of th e p o ts were w ell mixed, samples were taken, a i r d rie d and screen ed. The d eterm inations made on th e p o ts were as follow s: pH v a lu e , o rg an ic m a tte r determ in atio n s by th e Thomas-Wiliiams, W alkley-Black and by th e t o t a l carbon method.

A lso, base exchange c a p a c ity was run

b e fo re and a f t e r o x id a tio n w ith H O *. A ll th ese methods have been 2 2 d e scrib e d above and th e r e s u l ts a re given in Table 3«

Discussion Ihren though th e d a ta shorn i n th e ta b le s a re more o r l e s s s e l f ex p lan ato ry , th e d isc u ssio a i s given to emphasize c e r ta in im portant p o in ts and to p o in t o u t th e r e la tio n o f the v a rio u s f a c to r s .

For

in s ta n c e , in Table 1 , th e re can be seen th e e ffe c tiv e n e s s o f th e methods f o r determ ining th e organic m a tte r c o n ten t o f th e v a rio u s s o i l s .

The

t o t a l carbon d eterm in atio n s i s taken as th e standard. The ammonia took o u t about 20$ of th e organic m aterial*

There

seemed to be no r e l a ti o n between th e organic m a tte r d isso lv e d and e ith e r th e t o t a l organic m atter o r organic base exchange c a p a c ity . I t i s p o s s ib le t h a t i f d ilu te HCl had been used p r i o r to the ammonia treatm en t, h ig h e r and more s ig n if ic a n t v alu e s would have been o b tain ed . Hjypoiodite removed 25-50$ o f organic m a te ria l.

The KMnO^ method was

much l e s s e ff e c tiv e , g iving v alu e s a l i t t l e le s s than h a l f o f the b y p o io d ite .

The Thomas—W illiams method i s s im ila r in p r in c ip le to th e

Walkl ey-Bl ack procedure but employs a weaker o x id iz in g s o lu tio n .

It

i s presum able t h a t t h i s method e v alu ates th e organic m a tte r th a t may be expected to be w ell in co rp o rated in th e s o i l .

These two methods

appeared to give b e t t e r and more s ig n if ic a n t v a lu e s. The th re e o x id iz in g so lu tio n s invo lv in g c e ra te as an o x id iz in g medium b ear a c e r ta in re la tio n s h ip to one another but vary in t h e i r e ffe c tiv e n e s s .

The p e rc h lo ra to c e ra te being th e m ild e st o x id iz in g

medium o f th e group.

These th re e methods removed th e organic m atter

more in p ro p o rtio n to th e organic exchange c ap a city than th e o th e r methods. B leaching powder Was also used as an o x id iz in g agent b u t the r e s u lts

13

were n o t in clu d ed i n th e ta b le .

Shis method needs f u r th e r in v e s tig a tio n

i n view o f th e f a c t th a t only s lig h t v a ria tio n s were shown i n th e r e s u l t s f o r h ig h ly v ary in g so ils*

The v alu es obtained ranged from 2.03

to 2.38 p e rc e n t org an ic m a tte r. There i s shown i n Table 2 th e base exchange c ap a city o f the unox! d i zed and o x id iz e d s o i l s and the base exchange c ap a city due to the o rg an ic m a tte r a lo n e .

I f th e o rganic exchange c a p a c ity f o r each s o il

i s d iv id ed by the percentage organic m a tte r found by th e d i f f e r e n t methods i t i s b e lie v e d a re la tio n s h ip w ill be o b tain ed .

I f th e same

num erical v a lu e i s ob tain ed f o r a l l te n s o ils then th e re i s a d e f in ite r e la tio n s h ip .

This was done a s i s shown Ty th e r e s u l t s in T a b le d .

A casu al survey o f th o se d a ta in d ic a te th a t f o r some o f the methods th e re does seem to be a re la tio n s h ip between th e o xidized organic m a tte r and th e organic exchange c a p a c ity .

In o rd e r to check t h i s , the

stan d ard d e v ia tio n as w ell as th e c o e f f ic ie n t o f v a r ia tio n were c a lc u la te d f o r th ese v alu es a s w ell a s those i n Table 3*

In Table U th e sm a lle st

c o e f f ic ie n t o f v a r ia tio n appears i n the S u lfa to C erate method where i t i s 0.l6o , and 0.195 f ° r

P e rc h lo ra to C erate method.

n o t a s good a v a lu e as th e S u lfato C erate method.

The l a t t e r i s

However, when th e

e ig h t s o ils th a t have th e l e a s t v a r ia tio n a re su b jected to such a s t a t i s t i c a l a n a ly s is the c o e f f ic ie n t o f v a ria tio n i s 0.091 f o r th e P ereh lo ra to C erate method and O .llS f o r th e S u lfato C erate method. The c o e f f ic ie n t o f v a ria tio n valu e o f 0.091 i s considered to be v ery s ig n if ic a n t.

The c o e f f ic ie n t o f v a ria tio n values ob tain ed f o r the

o th e r v alu es which were secured by d iv id in g th e organic exchange c a p a c ity by th e so lu b le organic m atter a re n o t considered to be s ig n if ic a n t.

It

would appear th a t th e values obtained fo r th e e ig h t s o ils by the Per**

Ik c h lo ra to C erate method i s approxim ately o n e -te n th th a t o f th e organic exchange capacity*

This would in d ic a te th a t t h i s ra p id method m ight

he u sed a s a means o f ev alu atin g th e organic exchange capacity*

Al­

though more d a ta w ill have to he obtained befo re t h is can be Ju s tifie d * I t appears a s i f one can e stim ate f a i r l y c lo s e ly the organic exchange c a p a c ity t y m u ltip ly in g th e amount o f organic m a tte r ox id ized by the P e rc h lo ra to C erate procedure by te n . In Table 3 ^

can be seen th a t th e treatm ent d e f in ite ly in flu e n c e s

th e org anic exchange capacity*

In o rd er th a t the e ff e c ts o f t h i s

treatm en t can be more c le a r ly seen the r e s u l ts o f Table 3 a re summer!zed in Table 3*

Cf th e green m a te ria l, green wheat very d e f in ite ly decreases

th e base exchange c a p a c ity w hile green a l f a l f a d id not low er i t q u ite so much*

In dry m a te ria l th e high, n itro g e n c o n ten t had l i t t l e e f f e c t

on th e organic exchange cap acity w hile low n itro g e n m a te ria l decreased it*

Organic m a te ria l alone and f e r t i l i z e r alone decreased th e organic

b ase exchange capacity* th e same thing*

Also lim e and f e r t i l i z e r to g e th e r d id about

Lime alone d id n o t d ecrease th e v a lu e s, b u t gave even

a l i t t l e h ig h er ones*

Then from th e se d a ta i t would seem th a t th e o r­

ganic exchange c a p a c ity can only be b u i l t up by th e use of organic re sid u e s high in n itro g e n th a t do n o t decompose too re a d ily along w ith th e Ju d iciou s u se o f lime* In the p a s t th e d i f f i c u l t y experienced insfctempting to o x id ize organic m a tte r has probably been due to i t s c lo se a sso c ia tio n w ith in ­ o rg an ic and m ineral m a tte r.

Since a g rea t deal o f both organic and

in o rg an ic a c tiv e m a tte r i s in the c o llo id a l form t h i s means th a t the o rg an ic and in o rg an ic c o llo id s a re very c lo s e ly r e la te d .

The im pression

acq u ired from th e l i t e r a t u r e b e a rs out t h i s observation as w ell as those

15

d a ta assem bled in t h i s in v e stig a tio n *

In th e l a t t e r case th e S ulfato

C erate and P e rc h lo ra te C erate probably o x id iz e th e organic m a tte r in th e r e la tio n i n which i t e x is ts i n th e organic exchange complex*

TABLE i c Organic M atter Content o f 10 Maryland S o ils a s Determined "by V arious Methods ___

S o il Types Used

Perc en t o f .Organic M atter Ohtained^'by _thg D iff e rg n t Methodg _____ Ammonia Potassium Ceric Walkley- Thomas- S u lfa to P ereh lo rato T otal B ypoiodite E x tra c tio n Permanganate Sulphate Black W illiams C erate C erate Carbon

st

St

St

St

St

St

St

St

St

Elk ton S i l t Loam

1.02

0.67

0.90

1 .8

3.1A

2 . 21)

1 .7

0.87

2.6

S assafras S i l t Loam

1.07

0.08

0.1)5

1 .6

1.92

0.59

1 .5

0.72

1.8

Portsmouth Loam

0.89

0.85

0.1)1

2.5

3.68

2.1)7

2 .5

1.25

1).02

S assafras Sandy Loam

1.10

0.21)

0.57

0.73

0.79

0.11

0 . 9s

0.33

0.75

C hester Loam

1.02

0.1)5

0.39

1 .9

2.16

1.77

2.08

0 . 9U

1.95

Manor Loam

1.05

0.21)

0.29

2.1

2.55

1.53

2 .2

0.93

2.1)5

Hagerstown S i l t Loam

1.02

0.22

0.27

2 .6

3.85

2.00

2.6

1.22

3.22

Congaree S i l t Loam

1.02

0.71

0.1|1)

2.1

3.56

2.21)

2 .3

0.86

1.93

Ash G ravelly Loam

0.97

0.U5

0.18

2.5

5.20

3.89

2.6

1.1)1)

5.60

Penn S i l t Loam

1.03

0.57

0.36

2 .3

2.88

2.00

2.5

1.05

2.56

o>

TABLE 2.

The Exchange C apacity, P ercentage o f Organic M atter and pH Values f o r th e 10 Maryland S o ils

S o il Types Used

?&s§_Bsc^fiSg§_(3gE§city_____________________?src§nt§g§_gf_Qrggnic_M att§r_______ Unoxidized Oxidized Organic Unoxidized O xidized L ost hy pH O x id izatio n Value m»e.

m .e.

m .e.

st

st

st

E lkton S i l t Loam

11.45

5 .S0

5.65

2.60

0.79

1.81

4.08

S assafras S i l t Loam

10.30

2.00

s . 30

1 .S0

0.52

1.28

7.58

Portsmouth Loam

16.62

4.00

12.62

4.02

1.19

2.83

4.57

6 .i4

1.40

4.74

0.75

O.23

0.52

5.63

C hester Loam

12.27

2.80

9.47

1.95

0.58

1.37

5.16

M anor Loam

15.09

4.30

10.79

1.21

0.73

0.48

6.57

Hagerstown S i l t L oam

18.29

6.90

11.39

1.59

0.95

0.64

6.98

Congaree S i l t Loam

12.23

3.30

8.93

0.95

0.56

0.39

4.64

Ash G ravelly Loam

16 . so

2.50

14.30

2.73

1.68

1.05

6.78

Penn S i l t Loam

14.82

3.20

9.62

1.26

0.77

0.49

5.77

S assafras Sandy Loam

H

TABLE 3,

The E ffe c t o f Organic M a te ria ls, Lime and F e r t i l i z e r on the pH Value, Organic M atter and Exchange Capacity o f B e lts v ille s i l t loam s o i l .

Eercfint..Q£_QrsaniC-Ma±ter_______ BaaeJSxchange-Qapaclty. P lot Number

S o il Treatment

pH Value

ThomasW ili iams

? 1 &2 3*4 5 &6

7 &8 9 & 10 11 13 15 17 19 21 23 25 27 29 31 33

& 12 & lit & 16 & IS & 20 & 22 & 24

& 26 & 28 & 30 & 32 & 34 35 36 37 3S

(L ). (F ).

None Wheat Straw Wheat Straw (F) Wheat Straw (L) (F) Wheat Straw ^LJ Green Wheat Green Wheat (F) Green Wheat (L) (F) Green Wheat (l ) Soybean Straw Soybean Straw (F) Soybean Straw (L) (F) Soybean Straw (l ) Green A lfa lfa Green A lfa lfa (F) Green A lfa lfa (L) (F) Green A lfa lfa ( l ) None (L) (F) Green Wheat (L) (F) Green A lfa lfa (L) (F) Wheat Straw (L) (F)

Lime F e rtiliz e r

4.4 5.0 4.7 5.1 5.1 4.5 4*5 4.5 4.9 4.9 4.7 5.5 4.2 4.6 4.6 5.6 5.1 7.0 7.0 7.0 7.0

2.36

1.29 1.49 1.42

WalkleyBlack

T otal Carbon

Unoxidized

Oxidized

Organic

*

*

m .e.

m.e.

m.e.

i.8 5 1.82 1.97 1.90

12.9 11.3 10.4

6.6

6.3 3.5 3.7 5.7 7.5

2.18 1.9^ 1.88

2.04

2.00

zM

1.77 1.48 1.48 1.54

2.01 2 . 1^ 1.81 2.07 2.25

2.12 1.83

1.55 1.72 1.48 1.24 1.48 1.90 0 0 0 0

1.70 1-75 I .63 1.78 2.32 1.86

1.91 0 0 0 0.65

1.80 1.85 1.83

12.0

13.S 8.1 12.0

1.78

8.5

1.83

11.6 11.7

1.82 1.78 I .83 1.83

1.78 1.82 1.82 1.00 2 .V»

2.37 2-33 2.31

10.7

12.2 12.2 12.5

11.5 10.0

9.S 1 .0 0 0 3.0

6 .7 6 .3

6.3 6.9 6 .8

7.4 6.4 6.7 5.2 4.7 4.9 5.S 5*4 5.! 4.7

0 0 0

1*5

1 .2 5.2 1.1 5.2

5.0 5.5 7.5 6.7 6.1 4.9 5.1

1 .0 0 0

1.5

TABLE 1|>.

The Value Obtained by D ividing th e M ill!e q u iv a le n t o f th e Organic Exchange C apacity by th e P ercen t of Organic M atter Secured w ith th e D iffe re n t Methods o f D eterm inations on th e 10 Maryland S o ils .

S o il Types Used

The Numerical Values f o r th e D iffe re n t Methods Ammonia Potassium C eric Walkley- Thomas- S u lfato P erch lo rato T otal H g^oiodite^Extraction^Perm anganate^Sulphate^Black___W illiam s^CeraJe_C erate_____Carbon

H k to n S i l t Loam

5.54

8.45

11.30

3.14

1.64

2.52

3.32

6.50

2.18

S assafras S i l t Loam

7.75

10.30

1.84

5.20

4.32

14.00

5.50

11.50

4.60

14.10

14.90

30.04

6.00

3.44

5.15

5.05

11.01

3.14

4.30

1.97

8.30

6.50

6.00

47.30

4.82

14.30

6.30

9.25

9.25

24.20

5.00

4.38

4.35

4.55

10.10

4.85

Manor Loam

10.02

44.50

37.00

5.15

4.22

7.05

0.90

11.60

4.40

Hagerstown S i l t Loam

11.01

51.50

42.00

4.36

2.95

5.68

4.35

9.30

3.52

Congaree S i l t Loam

8.75

12.50

12.20

3.42

2.50

4.00

3.88

io.o4

4.6o

Ash G ravelly Loam

14.70

31.80

79.50

5.70

2.75

3.69

5.50

9.90

2.56

9.35

26.00

26.80

4.18

1.85

4.80

3.82

9.15

3.76

9.4S

30.39

27.32

4.87

3.41

9.95

4.57

10.33

4.00

Portsmouth Loam CO CTj S assafras Sandy Loam CO ° C hester Loam

Wd

Penn S i l t Loam Averages

20

TABLE 5 .

The E ffe c ts o f S o il Treatm ents on th e Organic Exchange C a p a c i t y 0f a Soil*

S o il Treatm ents

Average Organic Exchange Capacity m.e*

Wheat Straw

5*2

Green Wheat

3*2

Soybean Straw

6 .U

Green A lf a lf a

3*2

Organic M a te ria ls Alone

h*2

F e r t i l i z e r Alone

^.1

F e r t i l i z e r and Lime Lime Alone

6 .3

SQMMAHT Ten re p re s e n ta tiv e Maryland s o ils were o x id ized with, n in e d iff e r e n t methods f o r determ ining th e organic m atte r c o n te n t.

Also the base

exchange c ap a city was determ ined "before and a f t e r o x id atio n o f th e s o i l s . O xidation was perform ed by means of 6$ One s o il was brought in to th e greenhouse and incubated w ith v a r y ii^ treatm en ts o f org an ic m a tte r, lim e and f e r t i l i s e r .

The base exchange

c a p a c ity was a lso determ ined on th ese samples b efo re and a f t e r o x id a tio n . From th e r e s u l t s o f a l l th e se treatm ents i t i s concluded th a t: 1.

There i s an in d ic a tio n th a t a ra p id method can be devised to estim ate th e organic exchange c ap a city o f th e s o i l .

2.

The u se o f o rganic m a te ria ls alone may a c tu a lly decrease th e org an ic exchange c a p a c ity o f a s o i l .

3«

The most s a tis f a c to r y method to in c re a se base exchange cap acity i s by th e u se o f nitrogeneous o rg an ic m a te ria l and lim e.

BIBLIOGRAPHY 1.

A sso ciatio n o f O f f ic ia l A g ric u ltu ra l Chemist. O ffic a l and {Tentative Methods o f A n a ly sis. 3rd E d itio n . Washington, D. C. 1930 .

2.

B a r t l e t t , J* B .# Ruble, R. W.t and Thomas, R. P . The In flu en ce o f Hydrogen Peroxide Treatm ents on th e Exchange Capacity o f Maryland S o ils . S o il S cience. *&* 123-12S. 1037.

3*

B roadfoot, W. M., and T|ynerf E« H. S tudies on Some F a c to rs A ffe c tin g th e Q u a n tita tiv e E stim ation o f th e Exchange Capacity o f Organic M a tte r. P ro c . S o il. S c i. Soc. o f Am. ki (193$ 156 . 19 *10.

4.

Cameron, F . £ . , and B reazeale, J . F . The Organic M atter in S o ils and S u b so ils. Jo u r. Am. Chem. Soc. 26 : 29-1*5. 190 U.

3.

Gammon, N. A« Base Exchange Study on Some Maryland S o ils . Master* s Thesis a t the U n iv e rsity o f Maryland (unpublished d a ta ) .

6.

McGeorge, W. T* Organic Base Exchange Coapounds i n S o ils . Am. Soc. Agron. 26 : 575-579* Ju ly 193^*

Jo u r.

7* Meyers, H. E* Physico-Chemical R eactions Between Organic and In c rg an ic S o il C olloids a s R elated to Aggregate Form ation. P ro c . S o il S c i. Soc. Am. 2 (1937)* 77* 193** 5.

M illa r, H. C«, Smith, F . B ., and Brown, P . E. The Base Exchange C apacity o f Decomposing Organic M a tte r. Jo u r. Am. Soc. Agron* 2S: 753-767* September 1936 .

9.

M uller, J« F . Some O bservations on Base Exchange in Organic M a te ria ls . S o il S c i. 35: 229-237. 1933.

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S o ils

1 1 . Norman, A. G., and Peevy, W. J . The O xidation o f S o il Organic M atter w ith Ifypoiodite. P ro c . S o il S c i. Soc. o f -Am. 1* (1939)* IS 3-IS S . 19l*0.

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S ch o llen b erg er, C. J . , and D re ib e lb is, F. R. A n aly tical Methods in Base Exchange In v e s tig a tio n s on S o ils . S o il S c i. 30: 161-172. 1930.

lH

S c o tt

W. W. Standard Methods o f Chemical A nalysis. Yoik. D. Van Nostrand Company. 1927*

N ew *

Volume 1.

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15*

Smith, 0* P ., and Duke, I*. R. C erate Oxidimetry* Chem. A nal. Ed. 13* 558- 560. August 19^1.

l6 .

Thomas, R. P . , and W illiam s, R. C. A Comparison o f the R e su lts o f Rapid T ests with th e Amounts o f A vailable N u trie n ts O btained by Q u a n titativ e Methods on Maryland S o ils . P ro c. S o il S c i. Soc. o f Am. 1 (1936)* 2^3-25^. 1937.

17*

Treadw ell, P . P . , and H a ll, W. T. A n a ly tica l Chemistry. New York. John Wiley and Sons, In c . 1930*

IS .

WalKLey, A ., and Black, I . A. An Examination of th e D e g tja re ff Method f o r determ ining S o il Organic M atter, and a Proposed M o d ificatio n o f th e Chromic Acid T itr a tio n Method. S oil S c i. 37* 29- 3S. 1934.

19 .

Walton, H. P ., Ion Exchange Between S o lid s and S o lu tio n s. Jo u r. F ra n k lin I n s t . 232* 305-336* October 19^-1*

20

Weir, W. W.

S o il Science.

Chicago.

Ind. Sag*

Vol. 2.

J . B. L ip p in c o tt Go.

1936*