A STUDY OF SOME EFFECTS OF SEVEN SYSTEMS OF FARMING UPON CROP YIELDS AND SOIL STRUCTURE ByLynn S* R o b ertso n , J r . AN ABSTRACT Subm itted to th e S ch ool o f G raduate S tu d ie s o f M ichigan S t a te U n iv e r s it y o f A g r ic u ltu r e and A p p lied S c ie n c e i n p a r t i a l f u l f i l l m e n t o f th e req u irem en ts f o r th e d eg ree o f DOCTOR OF HIILOSOPHY Department o f S o il S c ie n c e Year Approved ___________________ tL 19 55 . A STUDY OF SOME EFFECTS OF SEVEN SYSTEMS OF FARMING UPON CROP YIELDS AND SOIL STRUCTURE By Lynn S. R o b ertso n , J r . ABSTRACT Crop y i e l d s and s o i l s t r u c tu r e a n a ly s i s were d eterm in ed on e s ta b ­ l i s h e d crop r o t a t io n ex p erim en ta l f i e l d p l o t s . R o ta tio n cau sed no c o n s is t a n t d if f e r e n c e in su g a r b e e t y i e l d s from one y e a r to th e n e x t. The y i e l d s from some r o t a t io n s were not a s h ig h a s th e y m ight have been b e c a u se low n it r o g e n l e v e l s f r e q u e n t ly lim it e d grow th. A ls o , b la c k r o o t , a sugar b e e t d is e a s e , was p r e v a le n t d u rin g sev era l season s. T his d is e a s e seemed to m a n ife st i t s e l f e q u a lly in th e sev e n system s o f farm in g. However, where b e e ts fo llo w e d a l f a l f a brome h a y , r e c o v e r y from th e d is e a s e d id n ot appear to o ccu r a s r a p id iv or to th e same d eg ree a s in th e o th e r system s o f farm in g. Sugar b e e t s a f t e r b ea n s r e s u lt e d in th e h ig h e s t y i e l d s f o r th e 10 y ea r p e r io d . The lo w e s t y i e l d s occu rred in a ca sh crop r o t a t io n w hich d id n o t in c lu d e a n it r o g e n su p p ly in g legume c ro p . P h y s ic a l a n a ly s is o f th e sugar b e e t se e d beds showed l i t t l e or no d if f e r e n c e in s o i l c o n d it io n s . However, d if f e r e n c e s in th e ro o t bed d e v e lo p e d l a t e r in th e s e a s o n . The ca sh crop r o t a t i o n , w hich d id n o t in ­ c lu d e a n itr o g e n -a d d in g legum e cro p , was in th e p o o r e st p h y s ic a l s t a t e a s was in d ic a t e d by a g g r e g a te a n a ly s e s , t o t a l and non—c a p i l l a r y p o r e -s p a c e a n a ly s e s , p en etro m eter r e c o r d s , and p e r c o la t io n s t u d i e s . The h ig h e s t corn y i e l d s o ccu rred where corn was p r eced ed b y a l e g ­ uminous hay cro p ; One year, a !.fa lfa -b ro m e i n a cro p r o t a t io n had th e same e f f e c t on corn y i e l d s a s d id two y e a r s o f t h i s hay in th e r o t a t i o n . Cl o v e r -tim o th y in a r o t a t io n in s t e a d o f a lfa lfa -b r o m e r e s u lt e d in 10 per c e n t s m a lle r y i e l d s . The p la c in g o f a sugar b e e t crop betw een an a . l f a l f a - brome hay crop and th e corn crop a ls o ca u sed a 10 p er c e n t r e d u c tio n in co rn y i e l d . The lo w e s t corn y i e l d s were o b ta in e d in a c a sh crop r o t a t io n w hich d id n o t in c lu d e a n it r o g e n add ing leg u m e. Dry s c r e e n a n a ly s e s o f se e d beds in d ic a te d th e r e was l i t t l e d i f f ­ eren ce in th e p h y s ic a l s t a t u s o f th e s o i l a t p la n tin g tim e . The r e s u l t s o f th e a g g r e g a te a n a ly s e s o f th e corn s o i l showed th a t th e sod crop In th e r o t a t io n was r e s p o n s ib le f o r th e d if f e r e n c e s in t o t a l a s w e ll a s w ater s t a b le a g g r e g a te s . The system s o f farm in g d id not a f f e c t th e s tr u c tu r e o f th e s o i l b elow plow depth s u f f i c i e n t l y to cau se m easurable d if f e r e n c e s . P o r o s it y d e te r m in a tio n s , b o th t o t a l and non—c a p i l l a r y # in d ic a te d th a t system s o f farm ing d id a f f e c t th e s tr u c tu r e o f th e s o i l . The h ig h e s t p e r c e n ta g e s were o b ta in e d on th e p l o t s where sod crop s were in c lu d e d in th e r o t a t i o n s . The lo w e s t p o r o s i t i e s were o b ta in e d from th e ca sh crop r o ta tio n s . P en etro m eter r eco rd s in d ic a te d th a t v a r io u s system s o f farm ing caused g r e a t d if f e r e n c e s in th e s tr u c tu r e o f th e s o i l and th a t i t was p o s s i b le to measure t h e s e d if f e r e n c e s w ith a p e n e tr o m e te r. A new ty r e o f T'ecordv.ig p en etro m eter was d ev elo p ed as a t o o l f o r rapid measurements and proved to b e s u c c e s s f u l1. A sim p le r a p id s o i l t e s t which i s b ased on t h e s t a b i l i t y o f so l* a g g r e g a te s to w ater was d e v is e d . A STUDY OF SOME EFFECTS OF SEVEN SYSTEMS OF FARMING UPON CROP YIELDS AND SOIL STRUCTURE By Lynn S. R o b ertso n , J r . A THESIS Subm itted to th e Sch ool o f Graduate S tu d ie s o f M ichigan S t a te U n iv e r s it y o f A g r ic u ltu r e and A p p lied S c ie n c e i n p a r t i a l f u l f i l l m e n t o f th e req u irem en ts f o r th e d egree o f DOCTOR OF PHILOSOPHY Department o f S o il S c ie n c e 1955 ProQuest Number: 10008416 AH rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest ProQuest 10008416 Published by ProQuest LLC (2016). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code Microform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 481 06- 1346 BIOGRAPHICAL SKETCH The a u th o r was horn Septem ber 1 9 , 1916 in L a f a y e t t e , In d ia n a , th e so n o f A d e lla C. and Lynn S. R o b ertso n . He a tte n d e d elem en ta ry and h ig h s c h o o ls in West L a fa y e tte and was gra d u a ted from Purdue U n iv e r s it y in 19*K), r e c e iv in g a b a c h e lo r o f s c ie n c e d e g r ee i n a g r ic u lt u r e . In 19^ 1, lie r e c e iv e d a m aster o f s c ie n c e d eg ree in a g r ic u lt u r e , h a v in g m ajored i n s o i l s and m inored in crop s and farm management. In 19A 1, he m arried E liz a b e th A in sw o rth . The same y e a r he was g r a n te d an A s s is t a n t s h ip i n th e S o il S c ie n c e D epartm ent, M ichigan S ta te C o lle g e w hich he h e ld u n t i l b e in g made a f u l l tim e em ployee o f th e departm ent in 19^3 • S in ce th a t tim e h i s p r in c ip a l i n t e r e s t s have c e n te r e d around s o i l f e r t i l i t y in v e s t ig a t i o n s p a r t i c u l a r l y in reg a rd t o th e h e a v ie r s o i l s . C u rren tly he i s a member o f th e I n t e r n a t io n a l S o il S c ie n c e S o c ie t y , S o il S c ie n c e S o c ie t y o f A m erica, American S o c ie t y o f Agronomy, American S o c ie t y o f Sugar B eet T e c h n o lo g is ts and th e S o c ie ty o f Sigma X i. ACKNOWIJTCMEHT The w r it e r e x p r e s s e s g r a t it u d e to Mr. Lee Ferden f o r th e la b o r a to r y f a c i l i t i e s w hich he so g e n e r o u s ly made a v a ila b le on h i s farm . T his s tu d y would n ot have b een p o s s i b l e w ith o u t th e la b o r a to r y in t o which he g r a t­ u i t o u s l y i n s t a l l e d e l e c t r i c i t y and runn ing w a te r . G r a titu d e i s a ls o e x p r e s s e d to D r. N. S, Hal] who h e lp e d o\rfc] in e th e p la n o f stu d y ; to Dr. G. E. M illa r and D r. R, L. Cook f o r t h e ir s u g g e s tio n s d u rin g th e c o u r se o f in v e s t ig a t i o n ; t o P r o f . C. M. Hansen who s u p e r v ise d th e c o n s t r u c t io n o f th e p en etro m eter; t o P r o f. E . G. S a ck rid er and Mr. B . A. Meyers o f th e S o i l C o n serv a tio n S e r v ic e f o r th e h e lp th e y p r o v id e d d u rin g some o f th e s o i l c o l l e c t i o n p e r io d s ; and to Dr. A. E. E r ic k so n , D r. R. L. Cook, and Dr. L. M. Turk f o r t h e ir s u g g e s tio n s d u rin g th e p r e p a r a tio n o f t h i s m a n u scrip t. Acknowledgement i s grateful.') y g iv e n to th e Farmers and M aniifacturers B e e t Sugar A s s o c ia t io n f o r t h e i r a s s i s t a n c e in th e e sta b lis h m e n t and m aintenance o f th e p l o t s upon w hich t h i s work was don e. SUABLE OF CONTENTS CHAPTER I. II. INTRODUCTION...................................................................................................... REVIEW OF LITERATURE OH CROPROTATIONSAND YIELDS . . . . A. G eneral Crop R o t a t io n s ............................ ..................................... B. Sugar B ee t R o t a t i o n s . ........................ C. III. IV. , Management o f Sugar B ee t R o t a t io n s ...................................... 1. P low ing tim e and t i l l a g e . . . . . . . . . . . 2. M a n u r e s............................................................................... .... 3. F e r t i l i z a t i o n ........................................................ .... 4. S o il s t r u c t u r e . . . . . . . . . . . . . . . . PLAN OF STUDY.................................................................................................. EXPERIMENTAL FIELD SET U P ....................... . . A. D e s c r ip tio n o f S o i l on th e Ferden Farm.. . . . . . B. D e s c r ip tio n o f E xperim en tal P l o t s and System s o f Farm ing. . . of ............................ ........................... V. GENERALOBSERVATIONS........................................................................... .... . V I. EFFECTS OF SYSTEMS OF FARMING ON CROP YIELDS............................ V II. V III. A. Sugar B ee t Y ie ld s ......................... B. Corn Y ie ld s . . . . . . ................... ...................................................................... PLOWINGTIME OBSERVATIONS....................................................................... METHODSUSED IN PHYSICAL DETERMINATIONS A, Dry Screen A n a ly s is o f Seed B ed s, B. A ggregate a n a ly s is o f Root Beds * • CHAPTER 1. C. IX. R eview o f l i t e r a t u r e . . . . . . . . . . . . . R eview o f l i t e r a t u r e * r , , X II. . . . . . . . . . . . . . . ............................................... .... . B. A ggregate A n a ly s is o f Corn and Sugar B eet Root Beds C. T o ta l and N o n -c a p illa r y P o r o s it y A n a ly s is o f Com and Sugar B ee t Root B ed s. X I. . . . Dry S creen A n a ly s is o f Sugar B ee t and Com Seed B ed s. . . . . . . . . . X. .. . , P e r c o la t io n S t u d i e s RESULTS OP PHYSICAL MEASUREMENTS A. ............................ .... P en etrom eter S tu d ie s o f Root Beds . . . . . . . . . 1. E* . , . P o r o s it y S tu d ie s o f Root B e d s .....................................• . , 1. D. Review o f l i t e r a t u r e . . . . D. P h ysical. D e ter m in a tio n s o f S o il Below E. P en etrom eter S t u d ie s . . • • • P. P e r c o la t io n S tu d ie s . . . . Plow D epth. . . . ..................................................... DISCUSSION....................................................... . SUMMARY....................... .... ................................................................................... HATES................................................... I. INTRODUCTION At a 1939 m eetin g of* agro n o m ists and o th e r s I n t e r e s t e d in. th e pro­ d u c tio n o f su gar b e e t s in M ichigan, a t t e n t io n was fo c u s e d on th e la c k o f e x p e rim en ta l r e s u l t s p e r t a in in g to crop r o t a t io n and seq uence under M ichigan*s c lim a t i c and s o i l c o n d it io n s . I t. was not. p o s s ib le to c i t e ex p e rim en ta l e v id e n c e in reg a rd to such q u e s tio n s a s , "What crop sh o u ld im m ed ia tely p reced e sugar b e e t s in a r o ta tio n ? Are legum es e s s e n t i a 1 in a sugar b e e t r o t a t io n , and i f so w hich legume has th e g r e a t e s t e ffe c t , on b e e ts ? What p o r tio n o f th e r o t a t io n tim e sh ou ld be a l l o t t e d to th e legum es?" In o rd er t o o b ta in s a t i s f a c t o r y answ ers to th e s e and o th er q u e s tio n s th e "Ferden su gar b e e t r o t a t io n experim en t was s t a r t e d in th e sp r in g o f 19*4-0. S in ce th a t tim e cro p s have been h a r v e ste d each y e a r . By 3 95^ th e r o t a t io n s had com p leted two c y c le s in w hich o b s e r v a tio n s and y i e l d d e t e r m l.nations had b een made. D e f in it e answ ers to some o f th e q u e s tio n s had been d eterm in ed , and a s u s u a lly o c c u r s , new q u e s tio n s had a r is e n . S in ce th e experim en t was s t a r t e d and p a r t ic u l a r ly a f t e r th e second c y c le o f th e r o t a t io n s t a r t e d , many o b s e r v a tio n s were made in regard to s o il s t r u c t u r e . Mr. Ferden had n o ted th a t th e s o i l In th e no .legume r o t a t io n plow ed harder than in o th e r r o t a t i o n s . Water seemed to d r a in ranre r a p id ly through th e s o i l on th e p l o t s where a 1 f a l fa. bad grown, ^he w orkers when b lo c k in g and th in n in g b e e t s , r e g u la te d th e speed o f t h e ir work s o . th e y w ould be a s s ig n e d th e ta s k o f b lo c k in g th e b e e t s which v e r s grown, a f t e r a! fa lfa -b r o m e hay b e c a u se "the ground., she s o f t In 1 i t f i e f"V "big f i e l d have hard ground” . The w orkers remembered t h i s d if f e r e n c e when th e y r e tu r n e d to work th e "beets fo r th e seco n d y e a r . The p u rp o ses o f t h i s stu d y were: 1, To summarize th e su g a r b e e t and corn y i e l d s du rin g th e second c y c le o f th e r o t a t i o n , 2. To r e p o r t o b s e r v a tio n s w hich were made d u rin g th e te n y ear p e r io d in reg a rd to both s o iJ s and c r o p s. 3, To make measurements on th e s o i l in o rd er to d eterm in e to what e x te n t r o t a t io n s had a f f e c t e d i t s p h y s ic a l p r o p e r t ie s . 4. To d e v e lo p a r a p id s o i l t e s t o f an e m p ir ic a l n a tu re w hich would g iv e an in d ic a t io n o f th e s tr u c tu r e o f a s o i l . II. A. REVIEW OE LITERATURE Crop R o ta tio n s— G eneral A g r e a t many s t u d ie s h ave b e e n made i n reg a rd to crop r o t a t io n s and t h e i r e f f e c t s upon y i e l d s . However, m ost o f th e s e s t u d ie s have n ot in c lu d e d su gar b e e t s , b u t p r im a r ily co rn , o a t s , w heat, p o t a t o e s , and c o tto n . Many have compared a c o n tin u o u s sy stem o f cro p p in g w ith a r o t a t io n sy stem . Wier (57) made a stu d y o f th e r e s u l t s o f r o t a t io n ex p erim en ts in v a r io u s p a r t s o f th e U n ite d S t a t e s and R otham sted, E ngland. He found th a t th e e f f e c t s o f f e r t i l i z e r s and o f crop r o t a t io n s , when b o th were u s e d , added to th e e f f e c t i v e n e s s o f each o th e r and th a t maximum y i e l d s w ere p o s s ib le o n ly when b o th were used t o g e t h e r . Lim ing a c id s o i l s in ­ c r e a s e d th e r e l a t i v e e f f e c t i v e n e s s o f crop r o t a t io n s in th a t i t r e g u la te d th e crop s w hich co u ld b e grown e f f e c t i v e l y in th e r o t a t i o n s . S im ila r c o n c lu s io n s may b e drawn from a la r g e number o f ex p erim en ts d e a lin g w ith g r a in crop s (6 , 1 5 , 1 9 , 5 1 , 5^, 5 7 , 5 8 , 5 9 ) . B. Sugar B eet R o ta tio n s The seq u en ce o f a l f a l f a - c o r n i s g e n e r a ll y c o n s id e r e d to be v e r y good b u t t h i s i s n o t th e c a se fo r a l f a l f a - s u g a r b e e t s . L e ig h ty (29) r e p o r ts th a t Mo r d in a r ily th e y i e l d s o f sugar b e e t s im m ed ia tely f o llo w in g a l f a l f a a r e low'1* L i l l and R ather (31) s t a t e th a t th e number o f organism s c a u s in g b la c k r o o t o f b e e t s i s i n t e n s i f i e d in q u a n tit y by th e grow ing o f a l f a l f a on in f e c t e d s o i l ; ‘'Hence under c o n d itio n s fa v o r a b le to b la c k ro o t o rg a n ism s, th e sta n d o f su gar b e e t s may be a f f e c t e d a d v e r s e ly i f a l f a l f a i s th e im m ediate f oreru n n er11. A fa n a s ie v , M orris and C arlson ( l ) showed th a t s e e d lin g d is e a s e s o f b e e t s occu rred in in c r e a s in g amounts where th e y were pjlanted a f t e r co rn , p o t a t o e s , o a t s , a l f a l f a , b e a n s , and b e e t s . H arris* (2 2 ) r e p o r t shows th a t su gar b e e t y i e l d s were h ig h e r in a r o t a t io n w hich in c lu d e d a l f a l f a than in one w hich in c lu d e d sw eet c lo v e r . I t was b e t t e r , how ever, to grow sw eet c lo v e r than to depend e n t i r e l y on n o n -leg u m es. B e e ts were n o t grown im m ed ia tely a f t e r a l f a l f a in any o f th e r o t a t io n s i n t h i s s tu d y . The e f f e c t o f c a sh crop s upon sugar b e e t y i e l d s a c c o r d in g to l u l l ( 3 0 ) w ith an o a ts —sugar b e e t s sequence taken a s a b a se a r e a s f o llo w s : b a r le y (+ 0 ,2 6 t o n s ) ; b eans (4 1 .4 4 t o n s ) ; and corn (+ 1*62 t o n s ) . In a n o th er p u b lic a t io n (3 2 ) L i l l in d ic a te d th a t th e seq u en ce o f so y b ea n ssu gar b e e t s was b e t t e r th an co rn -su g a r b e e t s . I f th e soybeans were c u t f o r h ay, th e y i e l d s were h ig h e r than i f th e soybeans were used fo r s e e d . C. Management o f Sugar B eet R o ta tio n s P low in g Time and T i l l a g e . S o il management p r a c t ic e s in a p a r t ic u la r crop seq uence can a f f e c t b e e t y i e l d s c o n s id e r a b ly . One y e a r* s d ata by T i.ll and. R ather (3 1 ) showed th a t m id-August plow ing o f a l f a l f a sod r e s u lt e d in h ig h e r b e e t y i e l d s th an d id sp r in g p lo w in g . R o b e r tso n 's (4 3 ) d a ta , how­ e v e r , showed th a t e a r ly s p r in g p lo w in g was b e t t e r than November p lo w in g . There i s need fo r more i n v e s t i g a t i o n in regard to tim e o f p lo w in g . T his problem i s b e in g in v e s t ig a t e d in a f i e l d experim en t s t a r t e d in M ichigan in 1950 ( 4 8 ) . I t i s th ought th a t im plem ents o th e r than th e plow a f f e c t th e s tr u c tu r e o f th e s o i l . Numerous f i e l d ex p erim en ts a r e now In p r o g r e s s to d eterm ine th e im portance o f t i l l a g e methods upon crop grow th. In regai'd to sugar b e e t s , Cook and P e ik e r t (1.2, 13)* in what was c o n sid e r e d to be a t y p ic a l r o t a t io n f o r th e a r ea in w hich th e ex p erim en ts were co n d u cted , r a th e r than a d e s ir a b le r o t a t io n , found g r e a t d if f e r e n c e s in weed p o p u la tio n r e s u lt i n g from v a r io u s t i l l a g e m ethods. They s u g g e s te d th a t w eeds in flu e n c e d growth more than d id th e r e s u l t i n g p h y s ic a l c o n d it io n o f th e s o i l caused b y d i f f e r e n t im p lem en ts. The r e s u l t s o f th e s e ex p erim en ts and o th e r s (4 7 ) in d ic a t e th a t a minimum amount o f t i l l a g e le a v e s th e se e d and r o o t bed In a more porous s t a t e . M anures. The v a lu e o f l i v e s t o c k manure i s a p p a r e n tly r e la t e d to th e n a tu r a l f e r t i l i t y c o n d it io n s o f th e s o i l r a th e r than to r o t a t i o n s . Nuchn]8 » (37) summary s t a t e s th a t g r e a t e r r e tu r n s were o b ta in e d by th e u se o f manure on low y i e l d i n g f i e l d s th an on f i e l d s o f h ig h e r p r o d u c tio n . The r e s u l t s o f Cook, M illa r and R ob ertson ( l l ) in d ic a t e th a t g r ee n manure, sw eet c lo v e r , a l f a l f a , or g r a s s a r e b e t t e r than s t a b le manure in fu r n is h in g n itr o g e n fo r young sugar b e e t p l a n t s . These c o n c lu s io n s were drawn from f i e l d and green­ house ex p erim en ts on what would b e c la s s e d a s good f e r t i l e sugar b e e t s o i l s . The u se o f manure f o r b e e t s a p p a r e n tly i s a d v o ca ted much more w id e ly in th e West than in M ichigan. Fer t i l i z a t i o n . There a r e v e r y few d a ta in regard to f e r t i l i z a t i o n in d i f f e r e n t crop r o t a t io n s . L i l l (33) in a p r o g r e ss r e p o r t , concluded th a t "the grow th o f th e a l f a l f a crop upon th e s o i l a p p a r e n tly had a ten d en cy to u p s e t th e b a la n c e o f p la n t fo o d elem en ts in th e s o i l by in c r e a s in g th e amount o f n it r o g e n and r e d u c in g th e amount o f ph osp horus" . T his I s In agree. menI w ith R o b e r tso n 's (4?) e x p la n a tio n o f why some y e a r s b e e t s a f t e r a l f a l f a resp on d more to h ig h f e r t i l i z e r r a te s than, do b e e t s a f t e r corn or w h eat. F urtherm ore, L i l l (33) c o n clu d ed th a t th e "un balan cin g e f f e c t o f th e a l f a l f a cro p upon th e m ineral p la n t fo o d e lem en ts may be c o r r e c te d t o such an e x t e n t by th e a p p lic a t io n o f p h o sp h o ric a c id to th e s o i l th a t th e sugar b e e t s e e d lin g can r e s i s t th e a t t a c k s o f th e b la c k r o o t organism s and make normal grow th". As fa r a s i s known, v e r y l i t t l e regard i s g iv e n to th e ty p e o f r o t a t io n b e in g p r a c t ic e d when p la n tin g tim e f e r t i l i z e r recom m endations are made. No r e fe r e n c e i s made in reg a rd to d i f f e r e n t methods o f f e r t i l i z a t i o n o r f e r t i l i z e r a n a ly s is in th e F e r t i l i z e r Recommendation B u l l e t i n (1 8 ) f o r M ich igan. However, f o r c e r t a in crop se q u e n c e s, p a r t i c u l a r l y where b e e t s f o ll o w sm all g r a in s , th o se who make f e r t i l i z e r recom m endations u s u a lly s u g g e s t th a t u n t i l th e tim e o f th e l a s t c u l t i v a t i o n th e n it r o g e n s t a t u s o f th e b e e ts be c l o s e l y o b se r v e d . Where d e f i c i e n c i e s o c c u r , n itr o g e n s id e d r e s s in g s sh o u ld be made. T heir recom m endations a r e p a r t i a l l y b a sed upon s id e .d ressin g r e s u l t s o b ta in e d on th e Ferden Farm (4 4 , 4 6 ) . S o il St r u c tu r e ♦ There has b een v e r y l i t t l e p u b lis h e d in regard to sugar b e e t r o t a t io n s and s o i l s t r u c t u r e . Farnsw orth ( l 6 ) and Farnsw orth and Baver (17) have made im p ortant c o n tr ib u tio n s in th e f i e l d o f s o l] s tr u c tu r e and su g a r b e e t r o t a t i o n s . T h eir work showed a d e f i n i t e r e la t i o n ­ s h ip b etw een crop p in g s y ste m s , non—c a p i l l a r y p o r o s it y , and sugar b e e t stan d and y i e l d s , Yoder (64) s t a t e s th a t "the o n ly p o s i t io n in th e r o ta tI o n th a t in s u r e s a s t r u c t u r a l s t a b i l i t y o f th e r o o t bed s u f f i c i e n t to in s u r e adeqoat a e r a t io n and d rain age f o r b e e t s i s to p la c e them im m ed ia tely a f t e r a sod crop. High o r g a n ic m a tter in p u t and g r a s s r o o ts b o th c o n tr ib u te t<-> w ater r e s i s t a n t s o i l g r a n u la tio n " . III. PLAN OF STUDY T his i n v e s t i g a t i o n was un d ertak en in o rd er to d eterm in e th e e f f e c t o f system s o f farm in g upon crop y i e l d s and upon s o i l s t r u c t u r e . If d if f e r e n c e s in s o i l s tr u c tu r e c o u ld be m easured, i t was hoped th a t th e d a ta c o u ld be u se d a s a b a s i s f o r th e developm ent o f a q u ic k t e s t o f an e m p ir ic a l n a tu r e w hich co u ld m easure s o i l s t r u c t u r e . The p la n o f stu d y in c lu d e d th e fo llo w in g : I II I ll Crop y i e l d s and o b s e r v a tio n on growth c h a r a c t e r i s t i c s . A. Sugar b e e t s B. Corn P low in g tim e o b s e r v a tio n s . P h y s ic a l d e te r m in a tio n s . A. Dry sc r e e n a n a ly s e s o f s o i l from corn and su gar b e e t se e d b e d s . B. A ggregate a n a ly s e s o f s o i l from corn and su g a r b e e t ro o t b e e d s . C. T o ta l and n o n - c a p illa r y p o r o s it y a n a ly s e s o f s o i l from corn and sugar b e e t ro o t b e d s . D. P h y s ic a l d e te r m in a tio n s on s o i l b e fo r e p low d ep th . E. Q uick t e s t s f o r d eterm in in g s o i l s t r u c t u r e . 1. 2. P en etrom eter s t u d ie s . a. Plum b-type p en etro m eter. b. M .S.C. p e n e tr o m e te r. P e r c o la t io n s t u d i e s . IV . A. EXPERIMENTAL FIELD SET UP D e s c r ijjtio n o f S o il on th e Ferden Farm The Lee Ferden Farm i s lo c a t e d i n th e sugar "beet grow ing a r ea o f Saginaw C ounty, M ichigan, th r e e m ile s so u th o f C hesaning i n th e NWj o f s e c t io n 33* T9N, R3E. The s o i l has b een mapped b y th e farm p la n n e r s o f th e S o il C o n ser v a tio n S e r v ic e , Saginaw , M ichigan, and i s d e s c r ib e d as h a v in g a s u r fa c e s o i l s im ila r to B rook ston or Clyde s o i l and a "brow nishy e llo w , h e a v y , p l a s t i c s i l t y c la y s u b - s o il s im ila r to T oled o" . V eatch ( 5 6 ) has in d ic a t e d th e s o i l on w hich th e p l o t s a r e lo c a t e d a s b e in g a member o f th e B rook ston s e r i e s . S o il a n a ly s e s showed th a t th e s u r fa c e s o i l c o n ta in e d 25 to 28 p er c e n t d a y and 50 to 58 p e r c e n t san d . B rook ston sandy c la y loam . I t , t h e r e f o r e , was c la s s e d a s a A ccordin g to .L y n d (34) th e s o i l co n ta in ed 7 ,8 p er c e n t o r g a n ic m atter; had a pH o f 6 . 8 , and a b a se exchange c a p a c ity o f 1 3 .4 5 m. e . p er 100 gins, o f s o i l , o f w hich 8 .9 5 ©* are c a lc iu m , 0 ,1 6 5 m. e . are magnesium, and 2 .4 5 m. e . are h yd rogen . An open d it c h l i e s a lo n g th e w est s id e o f th e p l o t s and th e f i e l d i s t i l e d a t e v e r y fo u r rod s. s lo w ly . However, th e s u b s o il s tr u c tu r e i s such th a t th e s o i l d r a in s r a th e r There i s a v e ry g e n t le s lo p e , 14 f e e t p er m ile , w hich a llo w s some s u r fa c e d r a in a g e , B. D e s c r ip tio n o f th e P l o t s and Systems o f Farming Seven 5 y©a** r o t a t io n s were s t iid ie d . They were a s fo llo w s : 1. B a r l e y , al f a l f a -o r o me, a l f a i f a - b r o m e , c o rn , sugar b e e t s 2. B a r i e y , a],fa] fa -b r o m e , a!fed fa-brome,' sugar b e e t s , noon 3. B a r i e y , a l f a l f a.- b r o me, a l f a l f a - ! r o m e , b e a n s , sugar u se rs 4. B a r i e y , o a t s , a l f a l f a , ■corn, su ga r b e e t s 5* B a r l e y , o a t s , c l o v e r - t i m o t h y , c o rn , sugar b e e t s 6, B a r l e y , "beans, w heat, co rn , sugar b e e t s 7* B a r l e y , g reen manure*, b e a n s, w heat, g r ee n manure*, corn , sugar "beets The green manure crop was seed ed with, b a r l e y and was plow ed under f o r b e a n s , and was seed ed in th e s p r in g on wheat to he plowed under f o r c o m . The p l o t s were arran ged i n a s p l i t p l o t randomised blocS: d e s ig n . Two f e r t i l i z e r r a t e s acco u n t f o r th e s p l i t p l o t d e s ig n . Sin ce the "high" f e r t i l i t y p l o t s (1 ,0 0 0 pounds o f 2- 16—8 per a c r e per r o t a t i o n ) have o u t y i e l d e d the low f e r t i l i t y p l o t s during th e f i r s t c y c l e o f th e r o t a t i o n , t h i s stu d y was made o n ly o n .t h e high f e r t i l i t y p l o t s . T h e re fo r e , f o r th e purpose o f t h i s s tu d y , the, p l o t s were t r e a t e d as a randomi 2e& p l o t e x p e r i­ ment. The r o t a t i o n s were r e p l i c a t e d four tim es and a i j crop s appeared each year* "Barley %nd sugar b e e t s o ccu rred in a!3 r o t a t i o n s . Corn appeared in a l l hut one o f the r o t a t i o n s . So f a r th e p l o t s have been d e scr ib e d a s a crop r o t a t i o n e x p eri men t „ A c t u a l l y , th e p l o t s r e p r e s e n te d system s o f s o i l managewri t w ith in g iv e n cron r o t a t i o n s . T h e r e fo r e , in t h i s t r e a t i s e the terms "crop r o t a t i o n s 1' and. “sy stem s o f farm! n.g" a r e used in t e r c h a n g e a b ly . The sy stem s ->f f a r ml »y have "been numbered— c a l l e d r o t a t io n number— f o r the sake o f c o n v e n ie n c e . * Mixture o f a l s i k e , -June, Mammoth, and sw eet c l o v e r . The u s e o f 1l i v e s t o c k manure, and th e d is p o s it i o n o f crop r e s id u e s were r e g u la te d a c c o r d in g to th e sy stem s o f farm ing w hich might he p r a c t ic e d w ith th e d i f f e r e n t r o t a t i o n s . In r o t a t io n s 1 , 2 , and 3 manure a t th e r a te o f 10 to n s p er a c r e was a p p lie d f o r corn and b e a n s. In r o t a t io n s h and 5 w it h 'o n ly 20 p er cen t o f th e lan d in h a y , a farm er would n o t fe e d a s many c a t t l e so th e manure a p p lic a t io n s were 7 to n s p e r a c r e , No manure was a p p lie d in r o t a t io n s 6 and 7 b eca u se under su ch farm ing- system s l i v e ­ s t o c k a r e n o t g e n e r a lly r a is e d . Corn s t o v e r was l e f t on a l l th e p l o t s . Straw and su gar b e e t to p s w ere r e tu r n e d to th e p l o t s i n r o t a t io n s 6 and 7 . A co m p lete d e s c r ip t io n o f th e p l o t s and how th e y have been handled has b een p u b lis h e d ( 1 0 ) . A ccord in g to th e o r i g i n a l p la n s f o r th e experim en t sw eet c lo v e r was to be see d e d in b a r le y and wheat in r o t a t io n ?• When t h i s was a tte m p te d , poor sta n d s o f sw eet c lo v e r r e s u lt e d b e c a u se an i n s e c t (Sw eet c lo v e r c u r c u lio ) devoured th e sm a ll p l a n t s . S t a r t in g i n 19*15 * a m ixture o f a l s i k e , J u n e, nammoth, and sw eet c lo v e r was s u b s t it u t e d f o r th e sw eet c lo v e r . ta in e d . S in c e th a t tim e , good sta n d s o f th e legum inous m ixture were ob­ V. GENERAL OBSERVATIONS D uring th e c o u r se o f t h i s ex p erim en t, s e v e r a l changes occu rred in th e p h y s ic a l s e tu p o f th e experim en t w h ich sh o u ld he m en tion ed . At a few l o c a t i o n s , sh o r t s t r i n g s o f t i l e were p la c e d be]ow c e r t a in s e r i e s o f p l o t s w hich seemed to d r a in s lo w ly . T hese t i l e have a id e d c o n s id e r a b ly i n d r a in in g l o c a l a r e a s w hich were n a t u r a lly w e tte r th an th e r e s t o f t h e fie ld . A ls o , th e open d it c h e s were c le a n e d out in 19A? and t h i s m a t e r ia lly d e c r e a se d th e flo w o f su r fa c e w ater a c r o s s t h e p l o t s in t h e s p r in g . On t h i s s o i l , ad eq u ate d ra in a g e i s o f prime im portance f o r s a t ­ i s f a c t o r y crop y i e l d s . S in ce i n s t a l l a t i o n o f t h i s a d d it io n a l d ra in a g e th e s o i l has been much more un iform and has worked up e a s ie r in th e s p r in g . The cro p s grown in t h i s experim ent were p ro b a b ly a d e q u a te ly f e r t i l i ­ zed in reg a rd to phosphorus and p o ta sh b e c a u se th e r e was l i t t l e e v id e n c e o f a d e f i c i e n c y o f th e s e n u t r ie n t s . T h is was n ot th e c a se fo r n it r o g e n , Som etim es, th e crop y i e l d s were low er than th e y would have b een I f ad eq u ate n itr o g e n had been a v a i l a b l e . The cash crop r o t a t io n s s u p p lie d much l e s s n itr o g e n th an did th o se r o t a t io n s w hich m ight f i t in t o a l i v e s t o c k system o f fa rm in g . P e r io d i­ c a l l y , th e corn y i e l d s w ere in c r e a s e d b y s jd e -d r e s s e d n itr o g e n even where corn fo llo w e d im m ed iately a f t e r an a lfa lfa -b r o m e hay c ro p . The su g a r b e e t s , d e s p it e th e f a c t th a t th ey r e c e iv e d p la n tin g tim e a p p lic a t io n s o f manganese and b oron , d u rin g some se a s o n s showed d e f i c i e n c symptoms f o r th e s e n u t r ie n t s . V I. EFFECTS OF SYSTEMS OF FARMING- ON CROP YIELDS Only th e y i e l d s o f su gar b e e ts and corn a re r e p o r te d in t h i s s tu d y b e c a u se th e o th e r crop s had some v a r ia b le o th e r than r o t a t io n w hich m ight in f lu e n c e th e y i e l d s . For exam ple, th e b a r le y was f e r t i l i z e d w ith 500 pounds o f 2 -1 6 - 8 in R o ta tio n s 1 , 2 , and 3; and w ith 250 pounds in 4 , 5* and 7 . T h e r e fo r e , i t would n o t be j u s t i f i a b l e to compare th e y i e l d s where th e r e w ere th e s e two f e r t i l i z e r r a t e s and s u g g e st th a t d if f e r e n c e s m ight be due to crop r o t a t i o n s . The crop y i e l d s o f th e f i r s t c y c le o f th e s e r o t a t io n s have been pub Id. shed ( l l ) » A. Sugar B eet Y ie ld s Sugar b e e t ro o t y i e l d s were u se d to in d ic a t e th e y i e l d r a th e r than pounds o f sugar p e r a c r e b eca u se sugar d e te r m in a tio n s have shown l i t t l e d if f e r e n c e s a s ca u sed by r o t a t io n s . T his p roced u re should reduce th e ex p erim en ta l e rr o r w hich might be o b ta in e d i f sugar a n a ly s e s were in c lu d e d i n th e in t e r p r e t a t io n o f th e d a ta . The su gar b e e t y i e l d s a re shown in Table 1 . No y i e l d s were o b ta in e d in 194? b e c a u se th e b e e t s had to be dragged tip a f t e r r e p la n tin g s f a i l e d , B lack r o o t d is e a s e d e c r e a se d th e stan d o f b o th p la n t in g s to such an ex­ t e n t th a t th e p l o t s had to be abandoned f o r th a t y e a r . In 1 9 4 8 , 1 9 4 9 , and I.95O a l l o f th e b e e t s had b la c k r o o t , b u t seemed to out-grow th e d is e a s e a s th e season n r o g i'e sse d . o b ta in e d . Alm ost a verage y i e l d s fo r th e a r e a were 1—1 © xr OS ON i—t rH on Sugar Beet Y ie ld s S s- 3p vO © s OS O n i—i i—i r-H -3 ’ Os rH O of Farming of IQ R O Eh SO o • Os © ■3 • CO V sC • O' 00 00 • CO V V O OS • V -3 00 CO * © rH -3 CM • o rH SO 3» o rH 3 © -3 so - • Os V V\ • © vs V • Os O rH • Os m O i—1 O o CSi 9 CO a 00 • © rH * * V so • © os V * CO -M -3 CM • rH CD © • © 1 t * CO • Jss rH 00 • 00 Os -3" * © i—i 1 I • CO • V V as V • 00 I 1 • CO * » Os rH On rH • Os * CO O '. c • © rH Os so • 00 vs o • o rH « 00 0 \ ON r 'l • CSi rH SO 00 • 00 ON ON • CSI V sO • r-l rH SC 3 • rH rH sc so • o r-i -3 SO • rH v 3 Ov rH © O • o o o o © © O • © © O • © O © O © o • © UN­ 3 CO • CSi rH so £V rH ON • 3 rH CM CM • ON r-i SO CM • rH iH rH © • ON. I—1 o> rH $he Effect os V • CD -3 rH Fi JP © Pm so Os * Os 3 3 os -=1“ SO • Os ON rH XT’ c3 Systems XT' -3 ON i—1 • O V on • o rH • o m so rH SO on • vs rH • * Vi ON • CM * rH 1 1 * ■» CO • *—i CM US ■ CM PP ca ■ ■ o 1 " if so ' —' r-i © O Qi R o © R 5» o o © co PQ CO o I pp m 9 4 1 . V\ § o •H P-H •H FI W) *H CO Hd » n * to • *H KM d A Q S T) c © R R © © r— ,c 3 Pdh © SP > — ) is. rH r-i »> d P aP.j 3 d pH R ; O a? & r f— O 1 d I © I 1 PP1 CO pp FP ‘3 o CO > +. £ d D uring th e f i r s t c y c le o f th e r o t a t i o n s , th e h ig h e s t y i e ld s o ccu rred where sugar h e a ts fo llo w e d two y e a rs o f a lfa lfa -b r o m e hay (R ot, 2 ) , ^he y i e l d s were somewhat h ig h e r than where sugar "beets fo llo w e d heans (R o t, P ). However, by th e end o f th e secon d c y c le t h i s d if f e r e n c e d isa p p ea red and th e y i e l d s a f t e r beans were h ig h er than th o se a f t e r a lfa ifa -b r o m e hay* Greenhouse exp erim en ts su g g e ste d th a t th e b e a n s-su g a r b e e t s sequence r e s u lt e d in h ig h e r b e e t y i e l d s than d id a lf a l f a - s u g a r b e e t s (l 1)* T his i s b eca u se th e y i e l d o f b e e t s a f t e r a l f a l f a has not been c o n s i s t e n t l y good. In f a c t , in 19^B, 19^9* &nd 195^ k*16 y i e l d s from R o ta tio n 2 ( a l f a l f a —brom e, b e e t s ) were lo w er than from th e cash cro p r o t a t io n (R o t, 6 ) , The d a ta in Table 2 show th a t th e low y i e ld s where b e e t s fo llo w e d a l f a l f a (R o t, 2 ) i n d i r e c t l y were r e la t e d to th e number o f m arketable sugar b e e t s . In seven ou t o f n in e y e a r s t h i s r o t a t io n produced l e s s m arketable b e e t s than d id any o f th e o th e r r o t a t io n s , The d a ta in t h i s t a b le a r e s l i g h t l y m is le a d in g in th a t a uniform sp a c in g o f b e e t s in th e row i s assum ed. T h is, how ever, was n o t th e ca se and i t p a r t i a l l y a c co u n ts f o r th e r e l a t i v e l y h igh sta n d co u n ts w hich some y e a r s were a s s o c ia t e d w ith r e l a t i v e l y low y i e l d s . R o ta tio n 6 ( a l l ca sh crop ) has c o n s i s t e n t l y produced low b e e t y i e l d s . The low y i e l d s a r e p a r t i a l l y a r e s u lt o f i n s u f f i c i e n t n itr o g e n b e in g s u p r lle d by th e s o i l in t h i s r o t a t io n . T h is was more e v id e n t in t h i s r o t a t io n than 5n any o f th e o th e r s (T able 3)» The b e e t s in a l l o f th e r o t a t io n s e x c e p t R o ta tio n 2 (b e e ts a f t e r a lfa lfa -b r o m e hay) recm ired more n itr o g e n than, was n a t u r a lly s u p p lie d by th e s o i l , The p la n t t i s s u e t e s t s rep o rted in T able 3 and t h e n i t r o g e n s id e d r e s s in g r e s u l t s showed t h is to b e t r u e . 0^ 00 cm £V o «H CM 00 NO co 00 00 CO ON PN On £~\ 00 NO CM On 1TN NO C£\ 00 On 00 O O a I— I CO NO CO ON CO IN­ 00 00 v*\ UN £>UN IN- IN- ON rH N- CO ON O O rH ON © o o u © -9 CM CO rfz* 3 pq CO UN NO NO NO 00 o CM IN- ON On CO ON ON INON O'', \0 ON O Cv. CM CM UN On N NO Hi o> -=fr 8 Vi o tD w 3 CO a © -p © rH © *8 CO 4^ © i © r^H © .3 © a o 14 -h © © © Vi u © r—i P3 rH © u © © © =«j aS © V i V f-r rO rCl rH o O! 1 © f 1 I © © 1 1 B pq pq h j o r^l •t— * o a •rl -H © 5 s*£. S_, r © c i> 4 OB O © a: 4-3 rH © © C n 1 Hr) c ( I 1 rH tj} c o s CO « 04 r—i SO CS• VO rH VQ C, J—i os v r, 1—1 -di—1 PQ }x} HI HI W 02 CM • VO CM • 1—i rH i—j O • os rH HJ . pq pq pq S. tH pq P5 pq w Jg H? Hi- pq HI w s: • rH Upon M trate Tissue Test of • V3 V/' »d *M CiO t i S •r) C eg 0) O i—i rP S i—i ,£j ni" W K ffi W ffi w w id id id id w id id i i i i J j, i pqi pel ts . H rH U W £ eg ■—! © a Pi P O CD P P o a pQ q O 4 P o P 43 © 63 *9 43 s O *3 P CQ O I 4 ffi J 1 pq © id K S }d td Eii) CO I— i .■ § £-1 td oi I S © OS pq r e p lic a tio n co CD 0) PQ id from all u 1 -=S o•? pq GO t o 1 d Composite The Effect of Systems of Farming ON 04 •H c\t OS ^ vr, vc is . 1. 7 The s i d e d r e s s in g r e s u l t s in 1948 showed an in c r e a s e in y i e l d rang­ in g from 0 .9 0 to n s in R o ta tio n 7 to 2 ,2 8 to n s in R o ta tio n 5* Two—h u ndrel pounds o f ammonium s u l f a t e was a p p lie d a t th e l a s t c u l t i v a t i o n . Tn 194Q. i n s p i t e o f th e f a c t th a t th e s id e d r e ss e d rows d id n o t c o n ta in as many h e e t s a s d id th e ch eck row s, s id e d r e s s in g in R o t a t i o n s .6 and ? in c r e a s e d th e y i e l d s 0 , 8 5 and 1 . 8 l t o n s , r e s p e c t i v e l y . The b e e t s were n ot s id e d r e s s e d in I95&* In t h i s ex p erim en t, th e e f f e c t o f r o t a t io n s upon b e e t y i e l d s was not a s g r e a t a s upon corn y i e l d s . T his i s un d ou b ted ly due td th e f a c t th a t sugar b e e t s fo llo w e d corn in a l l e x c e p t two r o t a t io n s . Corn fo llo w e d s i x d i f f e r e n t c r o p s. B* Corn Y ield.s In t h i s experim ent corn occu rred in o n ly s i x o f th e r o t a t io n s . The y i e l d s o f c o r n , as a f f e c t e d by r o t a t io n s , have b een v e r y c o n s is t e n t (T ab le 4 ) . The corn y i e l d s arran ged th em selv es in t o th r e e g ro u p s. Where corn fo llo w e d wheat (R ot. 6) th e y i e l d s were th e lo w e st in th e experim ent ev ery y ea r d u rin g th e 10 y e a r p e r io d . T his was p a r t i a l l y ca u sed by th e extrem e n itr o g e n d e f ic ie n c y w hich o ccu rred each y e a r . When th e corn was s id e d r e ss e d w ith n it r o g e n , th e y i e l d s were in c r ea se d to such an e x te n t th a t th e r e was l i t t l e d if f e r e n c e in y i e ld s i n t h is r o t a t io n and the r o t a t io n s which in c lu d e d a l f a l f a . In 1948, lp 4 9 , and 1950 th e y i e l d s in t h i s r o t a t io n were in c r e a s e d 1 5 *0 , 2 2 .1 , and 2 0 .0 b u s h e ls ,, r e s p e c t iv e ly , where th e corn was s id e d r e sse d w ith 200 pounds o f ammonium s u l f a t e a t th e tim e o f th e l a s t c u l t i v a t i o n , TTo s id e d r e s s in g was roade p r e v io u s to 1948, but . On vO IV Os rH rH -=t On UN Os Ht 00 UN • CM ov o> • o• UN 8 VO O XT' ■M O s CJs o U O UN Os rH Vi p Pi • 00 UN 00 tv 3 O s OS rH rH © • a NO © r © o ^ o s© Jh P O O) (1) w 0 O 1 fi C/Ti 4 PQ I PQ m PQ o I O © O J "1 © f- I! i— o o 4 A PQ CO PQ 1 A 'S PQ CO © -p © ciS £> a o 3 Pd pH H-> •H Q P tlfl •H CO a CO rP m +» © O E •rH -H o p © cO u © © P {> H- C l) P g3 csi P O (4 © OJ 3 ciS © * VV?. I | I ^ | IC E to pi (i) <5 o o t-i cj: c p o i— j *8 EH O O m anure-a]sike, The Effect of Systems of Farming on Corn Y ie ld s i—I rH 00 UN rH 3 7 .9 6 r-i C -4ir UN VO | d e f i c i e n c y symptoms and p la n t t i s s u e t e s t s in d ic a te d th a t se v e r e n itr o g e n s t a r v a t io n occu rred (T ab le 5 ) . The seco n d group in c lu d e s th r e e r o t a t i o n s , where corn fo llo w e d su gar b e e t s (Rot* 2 ) , where i t fo llo w e d c lo v e r -tim o th y hay (R ot, 5 )» and where i t fo llo w e d wheat w hich was seed ed w ith a legum inous g reen manure m ix tu r e . The corn y i e l d s in th e s e th r e e r o t a t io n s were c o n s i s t e n t l y h ig h e r than in th e c a sh crop r o t a t io n (R o t. 6 ) , bu t were low er than where corn fo llo w e d a l f a l f a . The one in c o n s is t e n t f i g u r e , in R o ta tio n 2 in 19^3, was th e r e s u l t o f th e sugar b e e t f a i l u r e i n 19^7- Thus in 19A8 c o m a c t u a l l y fo llo w e d summer f a llo w , w hich i n tu rn had fo llo w e d a l f a l f a , in s t e a d o f fo llo w in g su g a r b e e t s . T h is seco n d group c o u ld be su b d iv id e d in t o two s m a lle r groups on th e b a s i s o f grow th c h a r a c t e r i s t i c s . The corn w hich fo llo w e d th e w h e a t--g r e e n manure, and th a t w hich fo llo w e d th e c lo v e r tim o th y , c o n s i s t e n t l y responded to n itr o g e n s id e d r e s s in g , The in c r e a s e s in y i e l d due to n itr o g e n were s m a lle r , th ough, than th e y were in th e c a sh crop r o t a t i o n , • There was no d if f e r e n c e in m a tu r ity o f th e crop as in d ic a t e d by m o istu re d e te r m in a tio n s . The corn w hich fo llo w e d sugar b e e t s fr e q u e n t ly grew much slo w er than in any o f th e o th e r r o t a t io n s and s t a l k s rem ained g r ee n lo n g e r in th e fa ll. No d a ta a r e a v a ila b le in regard to m a tu r ity o f th e g r a in b eca u se th e corn was alw ays h a r v e ste d some tim e a f t e r a k i l l i n g f r o s t . E v id e n tly t h i s f a c t a c co u n ts f o r th e la c k o f d a ta showing a d if f e r e n c e in m a tu rity o f th e g r a in . A nother o b s e r v a tio n was made on t h i s r o t a t io n in. regard to th e c o lo r o f th e co rn b e fo r e i t reach ed knee h e ig h t . F rea u eritly many o f th e corn p la n ts had a p u rp le t in g e id e n t i c a l to th e phosphorus d e f ic ie n c y symptoms Tabi e 5 The E f f e c t o f System o f Farming U pon Corn P la n t T iss u e T e s ts f o r N it r a t e in 1 R o ta tio n Number N it r a t e T iss u e Test-*”"" D ate o f T est Crop Seauence P -3 . 6 -2 5 7 -5 7 - i o 7 - 1 S 8 - 1 8 - 9 8 - 2 0 9-*5 B u /A , H H H VH M L B L B 5 8 .2 H M M H H M I B B 5 3 »7 SB -B a-O —A-C H H H VH M M B B B 62.9 S B -B a-O -C l-C H H M M M I) B B B 59.r 1 SB —B a —A—A—C 2 B a-A -A -S B -C b 5 . , 6 SB-Ba-Be-W ^C H M H M B B B B B ^ 0 .8 rm-: f SB —B a ( pm) — Be H H H M B 1 B B B 5 ^ .1 —W(gm)-C VH—v e r y h ig h , B ~high, M-.med.iuni, L -lo w s B -b la n k SB -sugar b e e ts Be -b e a n s B a -b a r le y A - a l f a l f a brome hay C -corn C l- c lo v e r tim oth y hay V/-wheat gm -green manure m ixtu re o f a l s i k e , Ju n e, and sw eet c lo v e r O -o a ts C om posite s a m p le s from a l l r e p lic a t io n s d e s c r ib e d by Cook and M illa x ( 9 ) . phosphorus l e v e l . P la n t t i s s u e t e s t s in d ic a t e d a low T his d e f i c i e n c y seemed to be more in t e n s e du rin g th o s e s p r in g s h a v in g more than normal r a i n f a l l and lo w er th an normal t em p era tu res. The h ig h e s t corn y i e l d s o ccu rred where corn fo llo w e d im m ed ia tely a f t e r a lf a lf a - b r o m e . Whether th e alfalfar-b rom e hay was l e f t one or two y e a r s made no d if f e r e n c e in th e y i e l d s . The y i e l d s from th e s e two r o t a t io n s (R o t. 1 and U) have b een s i g n i f i c a n t l y h ig h e r than where corn fo llo w e d c lo v e r -t im o th y , sugar b e e t s , or w h ea t. The p la n t s in th e s e two r o t a t io n s h ave t e s t e d h ig h e r in n it r o g e n and n itr o g e n s i d e -d r e s s in g s have n o t m a t e r ia lly in c r e a s e d y i e l d s . P la n t t i s s u e t e s t s made d u rin g th e grow ing season have alw ays g iv e n p o s i t i v e t e s t s fo r P and K in th e p la n ts from a l l o f th e r o t a t i o n s . T h is in d ic a t e s th a t r e g a r d le s s o f th e f a c t th a t th e corn d id n o t r e c e iv e f e r t i l i z e r a t p la n t in g tim e , th e p la n ts o b ta in e d adequate amounts o f t h e s e two n u t r ie n t s . VII. PLOWING TINS OBSERVATIONS The e f f e c t o f sy stem s o f farm ing on th e p h y s ic a l s t a t u s o f th e s o i l was v ery n o t ic e a b le when th e p l o t s were b e in g p low ed. T his was more e v id e n t when th e p lo w in g was f o r corn than f o r b e e t s b ecau se co m fo llo w e d more d i f f e r e n t cro p s (P la te l ) . Com fo llo w e d two y e a r s o f a lfa lfa -b r o m e hay in P o ta tio n ] . When th e sod was plow ed, i t tu rn ed over in lo n g rib b on s and had a g lo s s y appearance* The s o i l appeared to be v e r y t i g h t or d e n se , but when, dry b roke in to fragm ents w ith most o f th e fragm ents v a r y in g betw een o n e - h a if and th r e e in c h e s in d ia m e te r . p lo w in g . T his has occurred w ith in 15 m inutes a f t e r The s o i l seemed to dry much more r a p id ly th an where some o th e r crop was plow ed un der. In R o ta tio n 2 , c o m fo llo w e d sugar b e e t s . When th e s o i l was olowed f o r c o r n , i t tu rn ed over in la r g e c lo d s , many o f them o v er a f o o t in d iam eter ( P la t e l ) . Under th e f e e t , th e plow ed s o i l f e l t tough and hard. D rying ca u sed v e ry l i t t l e fra g m en ta tio n o f th e c lo d s . When th e b e e t s bad been h a r v e ste d d u rin g wet w ea th er, as th e y were i n 19^8 * i t was p o s s ib le to o b serv e th e e f f e c t s o f t r a c t o r w h eels in th e plow ed s o i l , The tr u c k s w hich h a u led th e b e e t s to th e fa c to r y had more e f f e c t on th e s o i l than d id th e w h e e ls o f the h a r v e s t in g t r a c t o r . In e i t h e r c a s e , th e com pacted s o i l was e v id e n t even where th e furrow had been turned to a depth o f 8 or 9 in c h e s . The s o i l in th e w heel tr a c k s d r ie d s lo w ly and did not up r e a d ily w ith a d is c d u rin g seed bed p r e p a r a tio n . b reak S in ce th e s e o b se r v a ­ t io n s were made, tru ck s have not been a llo w e d on th e p l o t s , even though th e s o i l seemed r e l a t i v e l y d r y . p r e c e d in g c o r n . R o ta tio n 1 . R o ta tio n had one y e a r o f a l f a l f a More a l f a l f a r o o ts were v i s i b l e a f t e r p low in g than in The s o i l tu rn ed o ver in i n d i s t i n c t rib b o n s composed o f very a n g u la r fragm en ts v a r y in g b etw een one and th r e e in c h e s in d ia m eter . Upon d r y in g , th e fragm en ts broke in t o sm a lle r p ie c e s and th e s o i l had a s im ila r appearance to th e s o i l in R o ta tio n 1 e x c e p t th a t th e furrow s l i c e was le s s d is tin c t . Corn fo llo w e d c lo v e r -tim o th y hay in R o ta tio n 5* When th e s e p l o t s were p low ed , th e s o i l tu rn ed over in an i n d i s t i n c t rib b on composed o f sm all fragm en ts l e s s than two in c h e s in d ia m eter ( P la t e 3 ) . Upon d r y in g , the fragm en ts broke down in t o p a r t i c l e s no la r g e r th an th r e e -q u a r te r s in c h . In 19^*7 a *id 19*18, a f t e r p lo w in g manure sp rea d er tr a c k s were p l a i n l y v i s i b l e on th e p l o t s in t h i s r o t a t io n (P la te k ) . They were n o t seen on any o f th e o th e r r o t a t io n s . In R o ta tio n 6 , corn fo llo w e d w heat. When th e la n d was plow ed f o r e^m in t h i s r o t a t io n , th e in d iv id u a l furrow s l i c e s were n o t d is t in g u is h a b le in th a t th e y were composed o f sm all ( l e s s than one in c h ) a n g u la r fr a g m e n ts. The plow ed p l o t s were l e v e l and showed l i t t l e in d ic a t io n o f in d iv id u a l furrow s l i c e s . The fragm en ts d id n o t b reak down upon d r y in g . The s o il i n t h i s r o t a t io n alw ays seemed w e tte r than in any o f th e o th e r r o t a t io n s a t ■hiowing tim e , A lso th e plow d id n o t cu t a s wide a furrow and was harder to keen in th e s o i l when th e m oistu re c o n te n t was low ( P la t e 2 ) , In R o ta tio n ? , corn fo llo w e d wheat in which had been seeded a green manure m ix tu r e . At p low in g tim e th e furrow s l i c e s were not. d i s t i n c t and c o n ta in e d a la r g e number o f an g u la r fragm ents v a r y in g betw een one and tbrein c h e s in d ia m e te r . The s o i l was s im ila r to that, in R o ta tio n h, bu t upon d r y in g , t h e s e fragm ents did. n o t b reak up in t o s m a lle r fr a g m e n ts. In t h i s r e s p e c t , th e s o i l was s im ila r to th a t in R o ta tio n 6 . In R o ta tio n 2 , sugar b e e t s fo llo w e d a lfa lfa -b r o m e h a y . At p lo w in g tim e th e s o i l had th e same appearance a s d id th e s o i l on th e p lo t s in R o ta tio n 1 , where corn was to b e p la n te d . B e e ts fo llo w e d b ean s i n R o ta tio n 3» b u t th e b ea n s d id not a f f e c t th e c h a r a c t e r i s t i c s o f th e plow ed s o i l d i f f e r e n t l y th e b e e t s i n a l l o f th e o th e r r o t a t i o n s . th an d id corn which p reced ed When th e corn s to v e r was plow ed u n d er, th e s o i l tu rn ed o v e r a s i n d i s t i n c t rib b o n s composed o f v a r y in g s i z e d c lo d s . These o b s e r v a tio n s a lo n e a r e not o f much v a lu e . However, a f t e r a r a in i t was n o t d i f f i c u l t to se e th e r e l a t io n s h ip o f s o i l appearance to w ater s t a b le s o i l p a r t i c l e s . G e n e r a lly sp e a k in g , th e sm a lle r the s o i l p a r t i c l e s , th e l e s s d i s t i n c t rib b o n s d u rin g p lo w in g , th e l e s s s t a b le were th e s o i l p a r t i c l e s . g ra ss r o o ts . T his u n doub tedly was due to th e in f lu e n c e o f th e Under th e c o n d itio n s o f t h i s ex p erim en t, th e r e were alw ays more brome g r a s s r o o ts th an tim o th y r o o ts w hich p ro b a b ly accou n ted fo r th e more s t a b le s o i l p a r t i c l e s on th e s e p l o t s . V III. METHODS USED IN PHYSICAL DETERMINATIONS A, Dry S creen A n a ly s is o f Seed Beds Dry s c r e e n a n a ly s e s were made on s c r e e n s m easuring a p p ro x im a tely 2 x 4 fe e t. S o il was sam pled w ith a sm a ll square n o sed spade to a depth o f 3 in c h e s a t 20 random lo c a t io n s in each p lo t the day a f t e r the crop was p la n t e d . The t o t a l amount o f s o i l removed from a p lo t fo r s c r e e n a n a ly s is v a r ie d betw een 10 and 50 pounds. a g g r e g a te b reak age a t a minimum. Care was ta k en to keep a l l The s o i l th a t was caught on th e sc r e e n ’was removed and w eighed and th a t w hich p a sse d through th e scr e en dropped onto th e n e x t s c r e e n h a v in g a sm a lle r s i z e o p en in g . B. A ggregate A n a ly s is o f Root Beds S o il sam ples were c o l l e c t e d in th e s p r in g a f t e r p la n t in g tim e, but p r e v io u s to th e f i r s t c u l t i v a t i o n , w ith a spade to a depth o f 7 in c h e s . T his was a p p ro x im a te ly plow d ep th . p er p l o t . Samples were from fo u r random lo c a t i o n s The fo u r sam ples from each p l o t were c o m p o site d . A fte r th e s o i l was p a r t i a l l y a i r d r ie d , i t was p a sse d through a 10 mm sc r e e n and th en c o m p le te ly a i r d r ie d . b y s c r e e n in g . a n a ly s is . pared. The. m a te r ia l f i n e r than 5 ^ wa-s then removed The 5 to 10 mm m a te r ia l was th en u sed f o r a g g r eg a te T h is was done so th a t a g g r e g a te s o f u n iform s i z e might b e com­ P r e lim in a r y i n v e s t i g a t i o n s showed th a t t h i s p ro ced u re, u s in g u n i­ form s i z e s o i l p a r t i c l e s , reduced th e ex p erim en ta l e r r o r s . A c t u a lly the sc r e e n e d sam ple r e p r e s e n te d betw een 49 and 86 per c e n t o f th e o r i g i n a l s o i l sample depending on I t s m o istu re c o n te n t a t sam pling and s c r e e n in g tim e. There was no r e la t io n s h ip betw een the p er c e n t o f th e o r ig in a l s o i l sample u se d fo r th e a g g r e g a te a n a ly s is and th e system s o f crop r o t a t io n s . Water s t a b le a g g r e g a te s were determ in ed by th e p r in c ip le o u t lin e d by Yoder ( o 2 ) . The h aboratory-m ade w e t - s ie v in g ap p aratu s op era ted fou r n e s t s o f s i e v e s s im u lta n e o u s ly a t 30 s tr o k e s p er m inute through a d is t a n c e o f 50 mm. The s ie v in g tim e was 30 m in u te s. Standard w ire s ie v e s h a v in g a 6 in ch d ia m eter and o p e n in g s o f 4 .0 0 , 2 . 0 0 , 1 . 0 0 , 0 . 5 0 , 0 . 2 5 , and 0 .1 0 mm were u s e d . T w e n ty -fiv e grams o f th e s o i l was u se d f o r each d e te r m in a tio n . a i r dry s o il The was p la c e d on th e top s i e v e and the n e s t s o f s ie v e s were s e t in m o tio n . A fte r s i e v i n g , t h e s o i l m a te r ia l w hich had c o ll e c t e d on each s ie v e was d r ie d and w eigh ed . R eview o f L ite r a t u r e on A ggregate A n a ly s is . Bouyoueos ( 4 ) , Rhoades ( 4 l ) , C ole and E d le fse n ( 7 ) , and Yoder (6 2 ) have proposed methods fo r m easuring th e a g g r e g a tio n o f s o i l s , bu t Y oder*s p roced ure has p ro b a b ly been u se d a s much or more than any o f th e o th e r proced u res b ecau se o f i t s s im p lic ity . R e tze r and R u s s e ll (40) have s t a t e d th a t a l l o f th e pro­ ced u res are e m p ir ic a l in n atu re in th a t ca re in o p e r a tio n i s needed to o b ta in r e p r o d u c ib le r e s u l t s . Laws and Evans (26) have shorn a d e c r e a s e i n a g g r e g a tio n o f a r en d z in a s o i l r e s u lt in g from y e a rs o f cro p p in g . VahBave1 ( 5 5 ) has shown a d e c r e a se in a g g r e g a tio n from v ir g in sod to r o t a t io n a l corn to co n tin u o u s co rn . K lu te and Jacob (2 5 ) have shown th a t th e s t a b i l i t y o f a g g r e g a te s in th e 2 - 5 mm f r a c t io n sep a ra ted from th e a i r dry s o i l was s i g n i f i c a n t l y in c r e a s e d b y th e a d d itio n o f o rg a n ic m atter to s o i l s , These have been th e genera] c o n c lu s io n s o f o th e r in v e s t i g a t i o n s ( 2 0 , 24, 3 8 , 6n, C* P o r o s it y S tu d ie s o f Root Beds P o r o s it y d e te r m in a tio n s were made on a pF ta b le s im ila r to th e one d e s c r ib e d b y Learner and Shaw (2,8)* S o il sam ple c o re s were c o l l e c t e d from random l o c a t i o n s on th e su gar b e e t and corn p l o t s , e x c e p t th a t a t t e n t io n was p a id to row lo c a tio n * Core sam ples were alw ays tak en 10 in c h e s from th e c o m rows and ? in c h e s from th e b e e t row s. T h is was done to m inim ize th e e f f e c t o f th e s o i l w hich i s thrown tow ards th e rows during c u l t i v a t i o n . T hese d is t a n c e s from th e rows r e p r e s e n te d a r ea s where s o i l accu m u lation o r s o i l rem oval was a t a minimum* Cores were taken o f th e s u r fa c e s o i l and no a ttem p t was made to remove th e c r u s t s which a lw a y s formed* R eview o f l i t e r a t u r e on P o r o s it y . S lip h e r (50) has enum erated sev e r a l im p ortant req u irem en ts o f an id e a l s o i l s t r u c t u r e . be added. O thers co u ld perhaps Most o f th e req u irem en ts are d i r e c t l y r e la t e d to s o i l p o r o s it y even though some o f them a r e n ot o f an agronom ic nature* I t would seem th a t an id e a l s o i l s tr u c tu r e sh ou ld ( l ) o f f e r minimum r e s is t a n c e to r o o t p e n e t r a t io n , ( 2 ) perm it f r e e in ta k e and moderate r e t e n t io n o f r a i n f a l l , (b) -nrovide an optimum s o i l - a i r su p p ly w ith moderate g a seo u s exchange betw een s o i l and atm osp h ere, (U) h o ld to a minimum th e c o m p e titio n betw een a i r and w a ter fo r occupancy o f pore space volum e, (5 ) p r o v id e a maximum r e s is t a n c e to e r o s io n , (6 ) f a c i l i t a t e th e placem ent and co v era g e o f g reen manures and o th e r o r g a n ic r e s id u e s , (?) promote m icro b ia l a c t i v i t y , and (8 ) n r o v id e s t a b le t r a c t io n f o r farm inrnleraents. Thus a c c o r d in g to Yoder ( 6 1 ) , th e req u irem en ts o f a d e s ir a b le s tr u c tu r e are n ot o f a s in g u la r n a t u r e , hu* must meet " b io lo g ic , agronom ic, and e n g in e e r in g o b j e c t iv e s '1. I f s o i l p o r o s it y i s r e la t e d e i t h e r d i r e c t l y or i n d i r e c t l y to th e s e £8 , e ig h t c h a r a c t e r i s t i c s o f an 1dea'i g n ii s t r u c t u r e , i t i s e a s i l y u n d erstood why s o i l -p o r o sity d e te r m ir a tio n s are o f great, valu e* However, e x p e r ie n c e has shown t h a t t o t a l y o re sp ace d e te r m in a tio n s f a i l to a d e q u a te ly ch arac­ t e r i z e th e p h y s ic a l s t a t u s o f s o i l s in regard to p la n t grow th resp o n ses* At th e p r e s e n t tim e , p r o b a b ly th e b e s t known method and m o s t.w id e ly used method c h a r a c t e r iz e s th e s o i l as to b o th t o t a l pore sp a ce and a i r space* S e v e ra l te c h n iq u e s have b een d e v is e d fo r such, d e te r m in a tio n s ( 5 , 21 , £ 7 , 3 6 ) , b u t th e one o f Learner and Shaw (28) has been used most w id e ly b eca u se i t u t i l i z e s a sim p le a p p a ra tu s which a llo w s fo r rapid d e te r m in a tio n o f a la r g e number o f sam ples* B r a d fie ld and Jam ison ( 5 ) have su g g e ste d th e term " n o n -ca p il larv" p o r e s , th e p o r e s betw een th e a g g r e g a te s w hich r e g u la te d r a in a g e , n erco l a t i o n , and a e r a t io n , N elso n and Baver (3 6 ) have su g g e ste d th a t where on ly one te n s io n i s to be u se d to e x p r e ss non—c a p i1la r y p o r o s it y , the 1o g jc a 1 t e n s io n would be kO c e n tim e te r s o f w a te r, Baver and Farnsworth (2) shoved a d ir e c t r e l a t i o n betw een p o res d rain ed a t t h i s te n s io n and the y i e l d o f sugar b e e t s . These r e s u l t s would seem to in d ic a t e th a t f o r g e n e ra 1 work, one p o in t on th e no .re s i z e d is t r ib u t io n curve i s s u f f i c i e n t 1° g iv e a good in d ic a t io n o f th e s o i l ’ s p h y s ic a l s t a t u s i f th e proper p o in t i s c h o sen , Learner and Shaw (2.8) have s t a t e d th a t 11in th o se r e g io n s where t i ' i r g . i s n e c e s s a r y , te n s io n (in. c e n tim e te r s o f w a ter) ea n a l to th e depth, o f th e t i t e would seem to be v e ry s a t is f a c t o r y " „ T herefore in t h i s 5.n v esH .g a t 1 on a t e n s io n o f 90 c e n tim e te r s was u se d , which i s the approxim ate depth o f th e s h a l1owes t t i 1e » 29, D. P en etrom eter S tu d ie s o f Hoot Beds A s o i l p en etro m eter i s an in stru m en t w hich m easures th e r e s is t a n c e o f f e r e d by a s o i l to p e n e t r a t io n by a p r o b e . I t would seem th a t r e n e - tr o m e te r s sh o u ld have b een w id e ly u sed , b u t th e r e are s e v e r a l r ea so n s why t h i s h as n o t b een t r u e . The in stru m en ts are fo r th e most p a rt com­ p l i c a t e d i n d e s ig n , e x p e n siv e to b u ild , and b u lk y and la b o r io u s to u s e . A ls o , s o i l s a r e so h e te r o g en eo u s th a t a few r eco rd s from a g iv e n c l o t do n o t g iv e a tr u e p i c t u r e . B eview o f L ite r a tu r e on P enetrom eter S t u d ie s . b een p u b lis h e d ( l 4 , 23* 39* ^9» 5 3 ) * S e v e ra l d e s ig n s have P robably th e most novel id e a in regard to p e n e t r a t io n s t u d ie s i s th a t rec o r d e d by C uplin 0 4 ) when he u s e d a 0 ,4 5 c a l i b e r r e v o lv e r and measured th e depth o f p e n e tr a tio n o f th e b u l l e t a s an in d ex o f s o i l h a r d n ess. Many s o i l c o n d it io n s in f lu e n c e p en etro m eter r e c o r d s . Stone and W illia m s (9 2 ) and Reed (3 9 ) c o n sid e r e d t h a t p en etro m eter rea d in g s c o u ld he u se d a s in d ic e s o f p o r o s i t y . McKibben and. Hull (35) have shown v e r y high c o r r e la t io n c o e f f i c i e n t s betw een s o i l s t a b i l i t y ( r e s is t a n c e to com paction ' and p en etro m eter record s* Shaw, R a is e , and Farnsworth (49) concluded th a t s o i l m o istu re i s th e dominant f a c t o r in f lu e n c in g th e s e r e c o r d s . They a ls o f e e l th a t i t i s n ot p r a c t ic a l to attem pt to c o r r e la t e penetrom eter reco rd s in term s o f s p e c i f i c s o i l p r o p e r t ie s . R ichards (f 2 ) has shown how d i f f i ­ c u l t i t i s to se p a r a te th e e f f e c t o f r o o ts and s o i l . Many r e fe r e n c e s c i t e in s t a n c e s o f d i f f i c u l t y en countered in in t e r p r e t in g p en etrom eter r e c o r d s , th e same r e f e r e n c e s co n clu d e th a t th e p en etro m eter fu r n is h e s J u s t one o f th e many measurements th a t a r e n e c e s s a r y to e v a lu a te a g iv e n s o il c o n d itio n c o r r e c tly . E. P e r c o la t io n S tu d ie s The equipm ent u se d f o r th e s t u d ie s in c lu d e d g l a s s tu b es m easuring 1 3 f b in c h e s i n d iam eter by 8 in c h e s lo n g and s c r e e n s c o n ta in in g 64 o n es ix t e e n t h in c h round h o le s per square in c h . These s c r e e n s were suspended under one end o f th e g l a s s tu b e s . S o il was a i r d r ie d and p a sse d through a 4 mm s c r e e n . p a s s e d over a 1 mm s c r e e n . 1 mm s c r e e n was u s e d . I t was then- The s o i l m a te r ia l w hich was r e t a in e d on th e One-hundred cc o f s o i l was p la c e d in th e g la s s tu b e on a d i s c o f f i l t e r paper w hich had b een p la c e d o v er th e s c r e e n . The s o i l was soak ed f o r 40 hours in w ater and th en th e p e r c o la t io n r a te was determ in ed by m easuring th e tim e r e q u ir e d to p e r c o la t e 100 cc o f w ater th rou gh th e s o i l . A w ater head o f two in c h e s was m a in ta in ed d u rin g th e p e r c o la t io n tim e . A paper d is c was p la c e d on top o f th e s o i l to d e c r e a se a g g r e g a te d e s t r u c t io n w h ile w ater was b e in g poured onto th e s o n !. A s e r i e s o f exp erim en ts le a d in g up to th e d e s c r ib e d p roced ure were perform ed . The s o i l sam ples were sc r e e n e d to a uniform s i z e to a c c e n tu a te th e d if f e r e n c e s i n p e r c o la t io n r a te w hich o ccu rred b e f o r e s c r e e n in g . IX. A. RESULTS OF PHYSICAL DETERMINATIONS Dry S creen A n a ly s is o f Sugar B e e t and Com Seed Beds In p r e p a r in g a see d bed f o r corn or b e e t s , care was tak en to have a s n e a r ly a s p o s s i b l e th e same ty p e o f seed bed fo r a l l o f th e r o t a t i o n s . The amount o f work r e q u ir e d to f i t a see d b ed has been th e same f o r a l l r o ta tio n s . Seed bed p r e p a r a tio n has u s u a lly in c lu d e d two w orkings w ith a d ou b le d i s c and one w ith a sp r in g harrow fo llo w e d by a sp ik e harrow. O c c a s io n a lly some e x tr a work was n e c e s s a r y on sm a ll a r e a s b u t th e l o c a t i o n s were n o t c o n fin e d to c e r t a in r o t a t i o n s . Sugar B eet Seed B ed. The r e s u l t s o f th e d ry s c r e e n a n a ly s e s o f th e su gar b e e t se e d b ed s are shown in Table 6 . Crop r o t a t io n s ca u sed no d if f e r e n c e s in t h e s e a n a ly s e s . Corn Seed B e d s . The r e s u l t s o f the dry sc r e e n a n a ly s e s o f th e c o m s e e d b ed s are shown in T able 7 . The d ata show th a t the s e e d bed in th e c a sh crop r o t a t io n (R ot. 6) was s i g n i f i c a n t l y more c lo d d y than in th e o th e r r o t a t io n s . The p l o t s where corn fo llo w e d two y e a r s o f a lfs lfa -b r o m e hay (R ot. 1) c o n ta in e d 2 1 .4 p e r c en t more f i n e s o i l m a te r ia l than d id th e p l o t s where corn fo llo w e d wheat (R ot. 6 ) . T his would in d ic a t e th a t i t r e q u ir e s more work to f i t a s im ila r se e d b e d in a cash crop r o t a t io n th an in one w hich in c lu d e d two y e a rs o f a lfa lfa -b r o m e h a y . The c u r r e n t id e a © f red u cin g th e number o f t i l l a g e o p e r a tio n s to a minimum c o u ld b e p r a c t ic e d more e a s i l y where a r o t a t io n in c lu d e d a good a l f a l fa^-b rome c ro p . This ty p e o f r o t a t io n makes i t p o s s i b l e to f i t a *4 - a 00 rH cv• rH * •4* CO vna VO rH rH 00 rH rH 4 ona rHa cn rH a CO 4 CM a S' CO a CM i— ! a CM a i—J Hi O eg © £ o E {>-a Cn © Pi O 1 rH rH CM rH CM rH jjpc^ O’, • 4 4a 00 CM • O i—! CM « Ov 00a O «H 00 +5 fl (Ds CM • rH• 4 CM CO • ooa CM O-a cn VOa eg rH © opi % © rH eg o ■rn rH ■p., Oe cn r-i » •° «? rH* © eg Effect of Systems hW CJ\ •H pq 0i I 1 o pq r~i O ci <3 pq © pq CO oi I © pq <5 pq PI o •H •xi J 1 o 8) 'H ' Cg pq Pi © Pr CM cn -4 v", \o eg »H H eg © «M r*i rH eg £ Hi -H ! I eg pq CO I CO pq <4 CM £ « c E t>i rf 5 H> © Cg ,0 4^ « O p5 pq CO 4-' © © © 4-" © £ E 5w E Hco o eg V? rH © © E 'C O Cj o o O 3 1 > , © 3 1 1 i—> o o o PC: © E ' e £i- © 1 E J Q. 8 © >a (H ,£ 1 ' £o •H -p & -P a o £ Pi $3 O I PQ CO 1 j to pq PQ J o o I rH O a cS pS to £ O £ *H • rH o 0 t . © £ O <0 (—I cm rH t—J * O Cvi S CO o 4 J *1 © PQ 1 1 0) "if «u) 'cB PQ c& PQ I £ 1 1 a 5* •ri £ £ © -P © d s5 r] -d c © y £ © . © -p © © «© £ cO <*£] £ © 1 $ rH CD c3 ,£ CM VN VO CM © £ C £ rP cO X !>4 .£ ■p § •rl *P £ © © > £ -p *—3 I—i £ cO £ © O cO £ £ ■p rH © © cO C cO C rc r£ ,£ c 1 I & 1 "cO CO 8 1 rH © a PQ 4 o c o PQ *** © £ c3 .s P © © £ tiO £A 2U.I com parable s e e d "bed i n few er o p e r a tio n s* In n o t a t io n 4 , corn fo llo w e d one y ea r o f a lfa lfa -b r o m e h a y . The so31 in t h i s r o t a t io n d id n o t crum ble a s f i n e l y a s i t d id in R o ta tio n I . The hay i n t h i s r o t a t io n has n ev er c o n ta in e d a s much brome g r a s s a s has R o ta tio n 1 . T h is i s b e c a u se th e 'brome' g r a s s i s slo w to become e s t a b lis h e d and i t i s n o t u n t i l th e secon d y ea r th a t i t r e p r e s e n ts a v e r y s i g n i f i c a n t p a r t o f th e hay m ix tu r e. I t i s th ought th a t th e brome g r a s s was resp on ­ s i b l e f o r th e d if f e r e n c e in th e c o n d it io n o f th e s o i l i n th e s e two r o t a ­ tio n s . D if f e r e n c e s i n sta n d o f c o m p la n ts on th e s e p l o t s have n ot been n o t ic e d , so p o s s ib ly th e d if f e r e n c e s in th e se e d b ed s were minor in regard to s e e d g e rm in a tio n and g row th . Counts were made o n ly i n 1 9 4 ? . The numbers o f p la n t s were 958* 8 6 5 * 9 4 1 , 9 8 9 , 958* and 8 4 l p e r 1 ,0 8 0 f e e t o f row in R o ta tio n s 1 , 2 , 4 , 5* 6* and r e s p e c tiv e ly . These f ig u r e s in d ic a t e no r e la t io n s h ip to th e d if f e r e n c e s in see d b ed s a s measured in 1949. B. A g g r eg a te A n a ly s is o f Corn and Sugar B eet Root Beds C om Root B ed s. in R o ta tio n s 1 and 6 . In 1 9 4 6 , s o i l sam ples were tak en from th e corn p lo t * P r e lim in a r y in v e s t ig a t i o n s in d ic a te d a g r e a t and a m ean in gfu l d if f e r e n c e in th e r e s u l t s o f th e a g g r e g a te a n a ly s e s o f sajnples ta k en from th e two r o t a t io n s . The s o i l from th e l i v e s t o c k system o f farm ing c o n ta in e d g r e a t e r p e r c e n ta g e s o f th e la r g e a g g r e g a te s and th e a g g r e g a te s were more s t a b l e , a s i s shown in Table 8 , T able 8 The E f f e c t o f System s o f Farming Upon A ggregate >A n a ly s is o f Corn Root Reds in 1946 P a r t i c l e s r e t a in e d on each sc r e e n ($) P a r t i c l e s i z e d i s t r i b u t i o n (mm) R o ta tio n Humber Crop Sequence 1 0 -4 2 -1 1 - .5 •5- . 2 5 1 SB—Ba — A—A—C 1 1 .4 9 .4 1 4 .0 2 1 .2 1 9 .2 1 3 .0 6 SB—Ba-B e-W—C 9 .3 7 .0 1 3 .7 2 5 .1 2 3 .5 1 6 .7 le s s . 2 5 - .1 0 .1 ^ SB -sugar b e e t s B a -b a r le y A - a l f a l f a brome hay C -eorn B e-b ean W—wheat T able 9 The E f f e c t o f System s o f Farming upon A ggregate A n a ly s is o f Corn Root Beds in 1947 . P a r t i c l e s r e t a in e d on each scr e en (f>) P a r t i c l e s i z e d i s t r ib u t i o n (mm) R o ta tio n ufiib er Crop Sequence^* 1 0 -4 4 -2 2 -1 1 - .5 .5 ” .25 1 SB-B a-A—A—C 8 .0 6 .6 6 .7 1 4 .6 2 2 .5 2 2 .6 1 9 .0 2 Ba-A-A-SB-C 8 .1 6 .6 6 .6 1 3 .2 2 6 .1 2 0 .8 l8 .6 4 SB-Ba-0-A-C 1 5 .1 7 .7 5 5 .7 1 5 .4 2 0 .0 1 4 .8 2 1 .3 5 SB-Ba-0—Cl-G 1 0 .5 8 .9 6 .2 1 1 .2 2 2 .4 2 2 .0 jp 0> ,L 0 .< 6 SB-Ba-Be-W-C 2 .6 4 .6 4 .8 9 .5 2 4 .2 3 1 .9 7 SB-Ba(gm )-Be -W- (gm)—C 8..6 5 .3 5 .4 1 1 .8 2 6 .0 2 4 .0 1 8 ,9 3 6 .6 1 0 .4 8 .4 8 .9 1 1 .7 8 .1 1 5 .9 B lu e g r a s s 1 B a -b a r le y B e-bean A - a l f a l f a brome hay O -corn SB -sugar b e e t O -o a ts C l- c lo v e r tim o th y hav W-wheat gm -green manure . 2 5 - .1 0 l e s s ,1 T able 10 The E f f e c t o f System s o f Farming Upon A ggregate A n a ly s is o f Corn Hoot Beds in 1949 1 SB—Ba-A—A-C 5 .4 2 Ba-A-A-SB-C 3 -9 4 . SB-Beu-O-A-C O 4 -2 . 5 -* 2 5 le s s 5*5 . 13*4 2 7 .0 2 7 .7 1? 4 .4 4 .9 1 2 .1 2 6 ,1 3 0 .4 IB 5*4 2 .9 5*8 1 3 .2 2 7 .5 2 5 .8 IB 1 2 .3 2 6 .5 2 8 .4 3? 21 1 1 - .5 * 2 -1 -j 1 0 -4 • CO Croo Sequence 00 Ho t a.t io n Number ro '-A P a r t i c l e s r e ta in e d on each' sc r e e n (f->) P a r t i c l e S iz e D is t r ib u t io n (rmn) 5 SB-Ba-O-Cl-O 7 .3 3*0 6 SB-Ba-Be-W-C 2 .1 2 .3 4 .1 1 1 .6 2 8 .4 3 0 .4 7 SB-Ba- (gm )-B eW—(gm)-C 1 .6 00 * ci 5*4 1 2 .9 2 8 .4 3 0 .2 T able 11 The E f f e c t o f Systems o f Farming upon A ggregate A n a ly s is o f Sugar B ee t Hoot Beds in ±947 P a r t i c l e s r e ta in e d on each scr e en (1 P a r t i c l e S iz e D is t r ib u t io n (mm) 1 0 -4 4— 2 2 -1 . 5 -.2 5 2 2 .9 2 4 .2 O”,' «t-n . 2 5 - .1 0 le s s * 1 Ba-A-A-C-SB 5*4 '8 .1 V/\ CO Crop Sequence-1* • 1 r-i > tation irfner 1 0 .4 2 C—Ba—A—A—SB 1 0 .6 7 .9 5*7 9 .9 2 1 .1 2 2 .5 2 2 .S 3 Ba-A-A-Be-SB 5*0 7 .6 5*5 9 .6 2,2 . 5 2 5 .4 2b . 4 4 Ba—0—A—C—SB 8 .1 7 .0 5*7 9 .8 1 9 .2 2 1 .9 t 'T# xhO 5 B a-O -C l—C-SB 6 .9 7 .1 5*2 1 0 .6 21.1 24*3 24,'-: 0 s Ba—B e—W—C—SB 6 ,3 CC • VC 5*7 9 .9 2 2 .8 2 5 .5 <-.J>.< ■ 7 Ba—(giri) —B e-W— (gm)—C-SB 7 .4 1 0 .5 6 .0 1 0 .2 2 1 ,1 2 1 .7 234 ,6 1 0 .4 8 .4 8 .9 -* 1 1 .7 8 .1 G rass Ba—b a r le y Be—bean A—a l f a l f a brome hay C -corn O -oat s C l- c ’J o v er t i moth y 1>ay SB -sugar b e e t s gm -green manure ' »■ The 194? aggre jgate a n a l y s e s . o f th e s o il f r o m t h e corn p lo t s (T ab le A in d ic a t e th a t one y e a r o f hay (Rot» 4 and 5) in a r o t a t io n r e s u lt e d in more w ater s t a b le a g g r e g a te s than d id two y e a r s o f h a y , hut such was n o t th e c a se in 3,949 (T able 3.0)* The d ata from a l l th r e e y e a rs show th a t th e s o i l from th e ca sh crop r o ta tio n was the l e a s t s t a b le and was a g g r e g a te d to a l e s s e r d e g r ee than was th e s o i l from any o f th e o th e r r o t a t io n s * Sugar B ee t Root B e d s» The a g g r e g a te a n a ly s e s o f th e s o i l from th e sugar b e e t p l o t s (T able 11) show l i t t l e R o ta tio n s 1 , 3» 4 , 5 * 6 , and 7 . d if f e r e n c e in a g g r e g a tio n betw een In R o ta tio n 2 ( b e e ts a f t e r a l f a l f a ) , th e s o i l was more s t a b le and b e t t e r a g g r eg a ted than th e s o i l in any o f th e o th e r r o t a t io n s * T his i s in agreem ent w ith o b s e r v a tio n s th a t have been made by th e b e e t w orkers a t b lo c k in g and th in n in g tim e and by Mr, Ferden a t c u l t i v a t i o n tim e . I f th e a g g r e g a te a n a ly s e s o f the corn and b e e t s o i l s are compared w ith th e a g g r e g a te a n a ly s e s o f s o i l under sod lo c a te d , in a l i t t l e u se d lall ey way a d ja c e n t to th e p l o t s , th e p o t e n t ia l v a lu e o f g r a ss a s an a g g r e g a tin g a g e n t i s f u l l y r e a li z e d . I n s p e c tio n o f th e s c r e e n s du rin g th e tim e th e a n a ly s e s were made showed c l e a r l y th e m echanical e f f e c t o f th e g r a ss r o o ts i n b in d in g some o f th e s m a lle r a g g r e g a te s to g e th e r to form la r g e r o n e s . I t i s th ought th a t th e a g g r e g a te a n a ly s is o f s o i l sam ples ta k en a t th e tim e t h e s e were o b ta in e d r e f l e c t th e in f lu e n c e o f th e p r e ce d in g c r o p . I f t h i s i s th e c a s e , th e g r e a t d if f e r e n c e in a g g r e g a tio n o-r th e s o i l ob­ ta in e d from th e c o m and sugar b e e t p l o t s in R o ta tio n 6 might s u g g e st ro(.y corn has an a g g r e g a tin g e f f e c t upon th e so S 1• The val 3 d i t y £Me id e a i s d o u o t f u l, "but th e d if f e r e n c e i s so s t r i k i n g th a t fu r t h e r in v e s t i g a t i o n a lo n g t h i s l i n e sh ou ld be made. C. T otal and N o n -C a p illa r y P o r o s ity o f Corn and Sugar B e e t Hoot Beds Com Root B ed s. T o ta l p orosity d e te r m in a tio n s made on s o i l sam ples c o l l e c t e d i n th e e a r ly p a r t o f th e grow ing sea so n su g g e ste d th a t th e r e was no d if f e r e n c e cau sed b y crop r o t a t io n s (T able 1 2 )* The sam ples from th e p l o t s where corn fo llo w e d wheat (R o ta tio n 6) c o n ta in e d p a r t i c l e s o f stra w and t h e r e f o r e , it. was thought th a t th e straw m ight s i g n i f i c a n t l y r a i s e th e t o t a l p er c e n t p o r o s it y . T h is , how ever, was n ot th e c a se but i t i s b e li e v e d th a t th e p r e se n c e o f th e straw d id m a t e r ia lly in f lu e n c e th e r e s u l t s o f th e d e te r m in a tio n s . The fragm ents o f stra w were s t i l l v i s i b l e in th e sam ples w hich were c o l l e c t e d a t corn h a r v e st tim e , but much o f t h e i r s tr u c tu r e had been l o s t s o th a t th e y p ro b a b ly d id not a f f e c t th e s e d e te r m in a tio n s n e a r ly so much as th ey d id e a r l i e r in th e s e a s o n . D e s p ite t h i s , a t h a r v e st tim e th e s o i l in th e cash cro p p lo t s c o n ta in e d th e lo w e s t p e r c en t pore sp a c e . The 1948 d a ta are in agreem ent w ith th o se obtained, in 1947. The r e s u l t s o f th e n o n -c a p illa r y pore space d e te r m in a tio n s showed no d if f e r e n c e in th e s o i l under th e d i f f e r e n t system s o f farm ing in 1 9 4 ? . In 3 948, a t h a r v e st tim e, th e s o i l in th e R o ta tio n 6 p l o t s had th e low est, n o n - c a n illa r y p ore s p a c e . The g r e a t e s t n o n -c a p illa r y p ore space o ccu rred where corn was p reced ed b y two y e a rs o f a lfa lfa -b r o m e hay, o f a lfa lfa -b r o m e sod in a r o ta tio n was e v id e n t , The e ffe c t , The legum inous green manure crop in R o ta tio n 7 , which p reced ed th e co rn , s i g n i f i c a n t l y in c r e a s e © o a i Ph © © p OOP 00 PH * - t 0) o oj 'Jon-Gapilla: CO CD P o Pi -P P CD O Total and a: 4J o I—I Sh © P-t P4 nd £ CO U o o u © 44 •P On O r-l u o upon Farming C •H rH UP *rl rH 6 • nt ‘pT c3 O -P ON i s - 1 o JSirH P H> UrH P t>© © -3O £ On p 1—I p t-, o cn of Systems of © 4-0 CH O a> o a3 Pi oo IN• 00 -*• ON 0 o 00 • o CP • co on • ON Ht * CP £N *up -3* ON i 1 • G O • In cn • rH i— t -3" • C M * C M rH a CM r“i o rH ON 0 rH i— 1 i i CO 0 r^r OP OP 00 -t Ht -p- rH cn » © CO rP -P Pc\i S © CN. * Hf- c \i Q \ rH i © O - O IPj -P" 00 fl$ ■ P -P o O o co 0 OP S’ CP o\ Effect up 00 ©C0 P 4 -' c aS P i— i ©© O Xj,h 1 I^ C M S' £> rH -p up P rH r-l (Tv P P rH © P) CO o o up JP rH o CO up CO P c Pi o a) o I Ph P 1 o © p o p o •H p a © CO 1 j PQ 1 PS cn <3* PQ O o 1 r-i O 1 J o c 1 CD PC' 1 t CD PQ 1 & 8 1 © CO PQ 1 j © PQ i r* v e bJj ' — ■■ © o 5Q © O •P < H -) •rH 1 CO P^i t P iJ • |H OQ •H *4—' 4-> «3 P •H .r l P h S © ? -t P ; © © -P •^5 © c u ^ i— 1 C O 3 - fc* p pi :-p c • CO © f\G c^ p © • p H IQ Cfl rQ P o 0 P , > -p -P © OJ u p VO IP- e© P •H Sr © - P © rC 4 O ,S fc; V— - o | ^ © "s t.0 o © p q £i w © Ph qj) I o I Pi C C j to u - p O E-i •iH -P o up >H © 0 © csJ r-j -p- © r-i «} ,-C Ht s>- c up u c\i r-i «* O p -< r H CO i>£ O © P t -P O'-. O ^—I Pi o• On PQ © i— ! •r-i CO * a\ r—iCvi OOP p •n rH m • o csS cS • -P- (1) ,c; 44 nt • O rH c k H cc, ro 4 4 © © © E c |J D 4 !H C r 4 d u © flH © © cd rH 1— i q j i P W vd c 7p J •H d CCS c o <+-> ? 4 © r~l i— 5 r . © © 1 C 03 > > CC 1 1 ,_ ^ C O o - -i PQ 1 Cvi O P H i' th e n o n - c a p illa r y pore sp a ce b u t was n o t a s e f f e c t i v e as was th e a l f a l f a brome i n R o ta tio n s 1 , 2 , and h . Sugar B e e t Root B e d s. P o r o s ity d e te r m in a tio n s were made on th e su gar b e e t p l o t s i n 19^7 d e s p it e th e f a c t th a t th e b e e t s were n ot har­ v e sted . The r e s u l t s o f th e June 12 sam plin g (T able 1 3 ) from r e p l i c a t i o n number one showed a d if f e r e n c e in t o t a l p o r o s i t y . However, th e d i f f e r ­ en c es were n o t c o n s is t e n t w ith p r e v io u s cro p s so i t i s b e lie v e d th a t the d if f e r e n c e s r e p r e s e n t n a tu r a l s o i l v a r ia t io n s r a th e r than th e e f f e c t s o f crop r o t a t i o n . P o r o s ity d e te r m in a tio n s were made a s h o r t tim e a f t e r th e b e e t s were r e p la n te d and th e r e s u lt s o f th e s e d e te r m in a tio n s in d ic a t e no d if f e r e n c e s cau sed by r o t a t i o n s . The r e s u l t s o f th e September d e te r ­ m in a tio n s show a s i g n i f i c a n t d if f e r e n c e in t o t a l p o r o s i t y . The p o r o s it y was h ig h e s t on th e p l o t where sugar b e e t s fo llo w e d a lfa lfa -b r o m e hay (R o t, 2 ) . The d if f e r e n c e s in t o t a l p o r o s it y betw een th e June 17 a-nd Septem ber 23 sam pling d a te s in d ic a t e th a t th e t o t a l p o r o s it y on th e s e p l o t s d e c r e a s e d a s th e grow ing sea so n p r o g r e s s e d . Such a d e c r e a se d id n ot o ccu r on th e p l o t s where sugar b e e t s fo llo w e d a lfa lfa -b r o m e h a y . The 19^6 r e s u l t s a re in agreement w ith th e 19^7 r e s u l t s . More con­ fid e n c e i s p la c e d in th e s e r e s u l t s than in th e r e s u l t s f o r 19^7 . b eca u se a much la r g e r number o f d e te r m in a tio n s were made. T h is r e s u lt e d in a b e t t e r p ic t u r e o f th e c o n d it io n s which a c t u a ll y e x i s t e d . The t o t a l poro­ s i t y was h ig h e s t on th e p l o t s where a lfa lfa -b r o m e hay preceded th e b e e t s , and s i g n i f i c a n t l y th e lo w e s t where b e e ts were grown i n a ca sh crop r o ta ­ t io n w hich d id n o t in c lu d e a n itr o g e n -a d d in g legum e. The r e s u l t s o f th e n o n -c a p illa r y p ore space d e te r m in a tio n s are shown i n T able 13* P r e v io u s to th e f i r s t c u l t i v a t i o n no d if f e r e n c e in non-capi"i ©4 cv § J S Pi CO\ CO O r-i U\ ON © ON CM on • CM Os un 00 »4 u\ • d •rH r-i T1 o CO VI o © Q c3 Ph to © d O © CO rH • C*N 4 s O • I— i ON CM CM C M 4CM ON o ON CM ON CM IV rH CO Jzi • • m ON » 5 ** to • NO a CM © ON CM • CM • 4 4 ‘ 3 • i1 At * CM • C'N cs. © -4 d on. p rH •*5 NO • CM UN •P d © (—1 CNG rH CNd © © -4 d on Ph d rH •“D G *H -P Cj ■p d d s UN • S NO • o UN CO * C'N UN O • C'N UN rH • rH UN ON v r. UN 00 00 -4 v r\ OH u \ C M UN ON. CM C M UN un ON UN to a © d « CM es $ CM 8 8 1 O 1 <*5 l A fq I ■*=5 a <5 fq i o d i •? 3 pq co l o © o t I I rH o cl d a fq A fq S 0 i d1 ® 1 PC c r? |I •P © *§ EH ■P K O d cfl X} PS Js © | § o •H Vt •n d (© •rH fq CM UN, NO © d to © CO © cc. • cd I• od to iU tti A a I tu O © a c d cd t euo m 60 a - 4 st. Ho s i g n i f i c a n t d if f e r e n c e s o c cu rr e d in th e r e s u l t s o b ta in e d on th e s o i l s from R o ta tio n s 1 , 4 , 5» an& 7* The s o i l where b e e t s fo llo w e d beans co n ta in ed more n o n - c a p illa r y pore sp ace than d id th e s o i l where b e e t s fo llo w e d corn . D. P h y s ic a l D eterm in a tio n on S o il Below Plow Depth S e v e r a l in v e s t ig a t o r s have in d ic a te d th a t in order to m ain tain a d e s ir a b le s u b s o il s tr u c tu r e deep r o o te d legum es must be grown In a r o ta ­ tio n . They t h e o r is e th a t th e deep r o o te d crop s produce r o o ts w hich a re cap a b le o f p e n e tr a tin g th e n a t u r a lly more dense s u b s o i l . th e r o o ts i s m a n ife ste d in th r e e ways: 1 . The a c t io n o f A fte r th e r o o ts d ie , v e r t i c a l ch a n n els a r e l e f t in th e s o i l , thus im proving d rain age and a e r a tio n : 2 . The .roots and r o o t h a i r s , p h y s ic a lly and c h e m ic a lly , a c t a s a g g r e g a tin g a g e n ts th u s c a u sin g b e t t e r s tr u c tu r e ; 3 »' The deep p e n e tr a tin g r o o ts add much needed o rg a n ic m a tter to th e s u b s o il, th u s p o t e n t i a l l y im proving U s p h y s ic a l s t a t u s . A g g reg a te a n a ly s is (T ab le 14) and p o r o s it y d e te r m in a tio n s (T able 1 5 ) o f s u b s o il sam ples do not s u b s ta n tia te th e s e t h e o r ie s . However, i t may n o t be c o r r e c t to a ttem p t to e v a lu a te th e v a l i d i t y o f th e s e th e o r ie s on th e b a s i s o f th e e v id e n c e p r e se n ted b eca u se th ese r o t a t i ons are o n 1v Table 14 The E f f e c t o f System s o f Barming upon A ggregate A n a ly ses o f S o il Belov; Plow Depth - ? t o . 10 in c h e s in 194-7 R o ta tio n Number Per Cent C om position P a r t i c l e S iz e D is t r ib u t io n (nun) 1 Crop Sequence-*Corn P l o t s SB-B%»A-A—C __4 5 .7 4 -2 8 .3 2 -1 1 0 .8 1 - .5 1 6 .9 6 SB-B a-B e-W-d? 5 .2 8 .0 1 0 .0 2 B eet P lo t s C-Ba-A-A-SB 3 .4 7 -5 6 Ba-Be-W-C—SB 2 .1 1 1 .3 SB -sugar b e e ts B a -b a r le y A—a l f a l f a brorae hay C-corn. W-wheat B e-b ea n s >5->25 2 2 .1 .25-> 1 13*0 le s s __ *1 2 3 .2 . 1 6 .4 2 2 .9 15-4- 2 2 .1 7 .8 1 4 .6 1 8 .6 2 1 .2 2 6 .9 8 .5 1 5 .5 1 5 .2 1 9 .1 2 8 .3 Table 15 The E f f e c t o f System s o f Farming Upon N o n -C a p illa r y and T o ta l P o r o s it y o f S o il Below Plow D e p th '7 to 10 In ch es o t a t io n umber Crop Sequences^ Sugar B eet P lo t s U o n -C a p ill ary P o r o s ity 8 -4 -4 7 6- 15-h a 2 T otal P p ro s1 2 8 -4 - 4 ? 1 6 -1 5 -4 8 1 Ba—A—A—C—SB 7 .0 9 .6 4 5 .3 4 2 .2 2 C—Ba-A -A - SB 6 .9 1 0 .3 4 3 .8 4 1 .5 3 Ba— A—A—Be—SB 7 .0 8 .7 4 4 .5 4 2 .6 A Ba-O-A-C-SB 7 .0 8 .8 4 4 .5 4 3 .4 5 Ba-O-C-C-SB 6 .5 9 .3 4 4 .1 4 4.1 6 Ba-B e-W-C-SB 5 .8 1 0 .0 4 4 .1 4 3 .8 7i B a - ( gm )-Be-W -( gm)-C-SB 6 .2 . 8 .1 4 h* 9 3 Q.2 S ig n if ic a n c e U .S . U .S . P .S . IT. 0 . 7-.3 i_ h .73 6- .21-ha** Corn P l o t s 7 -3 1 -4 7 3 1-21-484 1 SB-Ba-A-A-C 6 .6 6 .4 4 2 .4 4 6 ,4 2 Ba-A-A-SB-C 6 .6 6 .9 4 4 .5 4 5 .3 4 SB-Ba-O-A-C 8 .7 7 .3 4 4 .2 4 4 .0 5 SB-Ba-O-Cl^C 6 .8 6 .6 4 5 .8 4 3 .1 6 SB-Ba-Be-W-C 5 .0 7 .6 4 3 .7 4 8 .6 7 S B -B a -(gm) -B e-W -( gm) - C 6 .6 6 .4 4 2 .9 44-. 2 S i g n i f i cance U. S. U .S . U .S . 17. s . ^ A verage o f 4 d e te r m in a tio n s from each r e p l ic a t io n A verage o f 10 d e te r m in a tio n s from r e p lic a t io n 1 and 2 ^ A verage o f 25 d e te r m in a tio n s from r e p lic a t i o n 1 an d 2 ‘4 A verage o f 10 d e te r m in a tio n s from eac n r ep j. i ca t non B e-beans 5 B a -b a r le y 0 1 -c 1o Ver t i mo th y hay A—a l f a l f a brome hay C -corn gm-green manure 0 -o a ts SB -sugar b e e t s 45. i n t h e i r seco n d c y c l e . The d a ta do i n d ic a t e th at i f th e t h e o r ie s are v a l i d , i t i s n ot p o s s ib le to improve s u b s o il s tr u c tu r e in a few y e a r s . The p r o c e s s must be in c lu d e d in a lo n g range p la n . E. P enetrom eter S tu d ie s Plumb Type P e n e tr o m e te r . In view o f th e o b s e r v a tio n s th a t had b een made in r e g a r d to s o i l s t r u c t u r e , p r e lim in a r y in v e s t ig a t i o n s w ith a s o i l p e n e tr o m e te r were s t a r t e d in 1 9 w ith an in stru m en t d e sig n e d by Stone and W illia m s ( P la t e 1 0 ) . T his in stru m en t has an ir o n plumb w e ig h in g 1500 gms* w hich i s dropped through a h o llo w tube from a h e ig h t o f a p p ro x im a te ly fo u r f e e t . The in c h e s o f s o i l p e n e tr a te d by th e plumb i s u s e d a s an in d ex o f th e p h y s ic a l s t a t u s o f th e s o i l . The in stru m en t h as one s e r io u s handicap in th a t o n ly th e su r fa c e s o i l i s c o n s id e r e d . T h is p en etro m eter has one advantage i n th a t a la r g e number o f rec o r d s can b e made from a g iv e n s o i l a r ea v e r y r a p id ly . in d ic a t e th a t t h i s i s a b s o lu t e ly n e c e s s a r y . The d a ta in Table 16 The d a ta shown i n t h i s t a b le were tak en from fo u r r e p lic a t io n s o f th e same tr e a tm e n ts and in d ic a t e an a v era g e p e n e tr a tio n in to th e s o i l o f 5*$ in c h e s by th e plumb. The d a ta show a s i g n i f i c a n t d if f e r e n c e betw een r e p lic a t io n s in th e experim ent a s w el] a s betw een h a lv e s o f th e same p l o t . T his ta b le i s in c lu d e d to i l l u s t r a t e some o f th e problem s en countered in making p h y sic a l, measurements o f th e s o i l p a r t ic u l a r ly whex'e i t i s n ot p o s s ib le to ta k e com p osite s o i l sam ples su ch a s th e s o i l ch em ist d o e s. The v a r ia t io n s a re u n d ou b ted ly due to d if f e r e n c e s th a t n a t u r a lly occur in th e s o i l and d if f e r e n c e s ca u sed b y v a r io u s t i l l a g e im p lem en ts. The d a ta from th e corn p lo t s (T able 1 7 ) show th a t crop r o t a t io n s d id Table 16 A Sample o f P en etro m eter R ecords Showing V a r ia tio n W ithin P l o t s (R o ta tio n 1— Sugar B e e t P l o t s R ecord Number 5“3 “ 4 6) In ch es o f P e n e tr a tio n bv P en etrom eter Plumb RR2 R1 m W . E W W E E E V/ 1 4 .5 4 .5 4 .8 5 .5 5 .0 4 .2 5 .0 3 .8 2 5 .0 4 .5 3 .8 5 .2 5 .5 5 .2 4 .5 5 .8 3 4 .8 4 .5 3 .5 6 .0 5 .5 4 .8 5 .5 6 .5 A 5 .2 4 .5 4 .5 6 .2 5 .2 6 . 0 • 5 .0 7 .8 5 4 .8 4 .2 CO • -3~ 6 .2 5 .5 5*5 5 .0 6 .8 6 4 .5 4 .0 5 .0 4 .2 4 .2 5 .2 5 .0 4 .2 7 3 .3 6 .0 4 .5 4 .5 5 .0 4 .2 5 .0 a 5 .2 5 .0 5 .2 6 .0 ' 5 .2 5 .2 4 .2 6 .8 5 .5 9 4 .5 7 .0 4 .2 5 .5 JC ° 5*0 5 .0 6 ,2 10 5 .0 5 -5 4 .8 4 .8 4 .5 6 .6 7 .0 5 .0 Mean 4 .7 3 4 .8 5 4 .5 1 5 .0 0 5 .0 3 "5.11 5 .3 0 5 .4 8 5 .0 0 Range 1 .4 1 .7 2 .0 1 .3 2 .8 4 .0 4 .3 13 .o 2 .6 R— r e p l i c a t i o n ; E—e a s t one—h a l f o f p lo t ;' W— w est one—h a l f o f p i o i . CM CM tA 3 FR VA VO •3" 1 VA 3 VA • vo • 3 CD • CO • CA • 3 3 3 '© • -3 to 3 CO • VA VA • VA VA • VA VA • VA VQ • VA VO • VA 3* • VA CO S* CM. © rH CA « hj * <0 2f u © s CO • OV • 3 3 Cv * -3 Ov • -3 O • VA OV VA * -3 3 0 § CO © u eft a fr H •p 3 eft ■— 1 3 © © © PR 3 eft Ctfl d CO p» 3 3 O O s o\ 1—1 »d 3 eft «k t>3 OV i-l •» 3 O CO •d 3 0 0 © 3 © P © a 0 3 p © 3 © Ph 1 vo r-4 Ph p s o\ rH 3 »rt P © a 0 3 p © 3 © Ph r*i r° 3 «H O m 3 eft va -3 ■ va w !§ c*s VA CA AA VA VA 3 CM CA •• CA ca CA CA VA 'A VA 'A VA VA • CA CA • CA VO « CA 3 «■ CM • o © § rH I I>- * ca CA 3 O CA • CA P © rH vo 3 I ca l VA VA c- r- A- 3 3 -3 3 vo 3 O *H 3 © rQ «S p a o p Ph JSI CA m o © O 3 eft O •H Vs ■8 EH P o\ ■ VA CM CA VA VO 3 *U J •H IO VA P eft • p ■ C O • p o to 3 c -H P 3 3 CO •H 3 H O .3 *r( © P p eft © 3 ■d . 3 if © P V) © o *d ©o 3P SP ' ‘ CM 3 ? -3 3 O V ao •r> C H •* V» £ cd o -P V. Ui c ® h c. P r~ 77’" c p i P I r~ . 4 C :6 P CO — CO o p X - s'X -P•H 6' -fJ Cfl f - o rrt c * 0 c 5, -*4/ C r C~- Q_ pH 0) *L_ C O c (—, — • c c> a’ c C3 *r rC. — c 5 sr- *^ 4-' -*■' 4- s c £ jj: C, V* c a a? % -p •r j f-J r£ c rC s .. 1 = V:; a> ^ Vi a a - _ V •u o a: r- a a> *r £< <£ a *~ c c X -+- s ftE P.-' c3 or a' aj t— 0. P la te 8, A -p ortion structu re 0 2 3 3*5 of of a a s o i l p r o f i Le v irg in s o il. (? "by 1 6 in ch es) sh ow in g to 2 in c h e s - gra n u les le s s tlian 1./8 i n c h d iam eter. to 1 in ch es - g ra n u les le s s than l/A in ch d ia m eter. to 3 .5 to 5 in ch es in ch es - the d e n s e g r a n u l e s wbi d i h a v e a ten d en cy t<"> s h o w a p i a t v t y p e o f s t r u c t u r e . g r a d u a tio n from s t r u c t n .re» the above to a hioc-V y 5 to 16 in c h e s - b lo c k y s t r u c t u r e . l'Tote - no c r u s t form ation o n th e s u r fa c e o f tPe snj i (compare w ith P l a t e 7) P la te S o il penetrom eter d ev elo p ed so il con d itio n s* A so il and a o f pressure so li depth. curve is I'eq u ired to m easure probe is drawn w h ich to force slow ly rela tiv e forced in d ica tes the probe to in to the a the pounds g iv er LITERATURE CITED 1. A fa n a s ie v , M* M .t M o r r is , H. E ., and C a r lso n , W. E. 19A2 The e f f e c t o f p r e ce d in g crop s on th e amount o f s e e d lin g d is e a s e s o f su gar b e e t s , P r o c . Amer, S oc. o f Sugar B eet Tech, A3 5-A3 6 . 2. B ^ e r , L, D ., and F arnsw orth, R. B . I 9A0 S tr u c tu r a l e f f e c t s in th e grow th o f corn and su gar b e e t s . S o il S c i, S o c. Amer. P r o c . 5: A5-A 8 . 3. B a v er , L. D. 1 9 A0 S o i l P h y s ic s , p p . 1 6 2 . John W iley and Sons. A. B ouyoucos, G. J . 1935 -A method fo r making m ech a n ica l a n a ly s is o f th e u lt im a t e n a tu r a l s tr u c tu r e o f s o i l s . S o il S c i . AO: A8I-A S5 . 5. B r a d f ie ld , R ., and J a m ison , 7 . C. 1938 S o il S tr u c tu r e — a ttem p ts a t i t s Q u a n tita tiv e c h a r a c t e r iz a t io n . S o il S c i, S o c. Amer. P r o c . 3 : 7 0 -7 6 . 6. C h r is t ie , G. I . 1 9 2 5 -2 6 Com parative V alue o f Crop R o ta tio n s . A gr. E xp t. Ann. R p t. 3 9 1 A2. 7. C o le , R. C ., and E d le fs e n , N. E. 1935 A s e d im e n ta tio n tube f o r a n a ly z in g w ater s t a b l e s o i l a g g r e g a te s . S o il S c i. AO: A73-A79. 8. Cook, R. L . , U npublished d a ta . L a n sin g , M ich igan . 9. Cook, R. L ., and M illa r , C. E. I 9A9 P la n t N u tr ie n t D e f i c i e n c i e s . M ich. A gr. E xpt. St a . Sp ec. B u i. 353 • In d . M ichigan S ta te U n iv e r s it y , E ast 10. Cook, R. L ., M illa r , C. E . t and R o b ertso n , L. S. 19A5 A crop r o t a t io n f i e l d la y o u t w ith an i l l u s t r a t i o n o f th e s t a t i s t i c s in v o lv e d in com bining s e v e r a l y e a r s d a ta . S o i l S c i . Soc. Amer. P ro c. 10: 213- 2 1 8 . 11. Cook, R. L ., M illa r , C. E . , and R ob ertson , L. S. in sev e n M ichigan systevns o f crop r o t a t i o n s . Sugar B e e t Tech. 7 3 -8 7 . 1 2 . 13. 19A6 Sugar B e e ts P r o c . Amer. Soc. Cook, R. L ., and P e ik e r t , F. W. I 9A9 A com parison o f t i l l a g e im p le­ m ents and t h e ir e f f e c t on crop y i e l d s . M ich. A gr. E xpt. S ta . Q uart. B u i. 32: 10A -118. Cook, R. ! . , and P e ik e r t , F. W. 1950 m en ts. 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