EFFECT OF LTGNIN ON SOIL PROPERTIES AND PLANT GROWTH By Ming Yuen Wang A THESIS S u b m i t t e d t o t h e S c h o o l o f G r a d u a t e S t u d i e s o f M ich ig an. S t a t e C o l l e g e o f A g r i c u l t u r e and A p p l i e d S c i e n c e in p a r tia l f u l f i l l m e n t o f the re q u ire m e n ts f o r the degree of DOCTOR OF PHILOSOPHY D epartm ent o f S o i l S cien ce Year 1953 EFFECT OF LIGHIH ON SOIL PROPERTIES AND PLANT GROWTH / By Ming Yuen Wang AN ABSTRACT S ubm itted t o th© School o f G raduate S tu d ie s o f M ichigan S ta te C o lleg e o f A g ric u ltu r e and A pplied S cie n ce i n p a r t i a l f u l f i l l m e n t o f th e re q u ire m e n ts f o r th e d eg ree o f DOCTOR OF PHILOSOPHY D epartm ent o f S o il S cience Year Approved JLfajZtiJL 19!?3 ABSTRACT The E ffect; of L Ig n in Ming Y u e n Wang L i g n i n on S o i l P r o p e r t i e s and P l a n t Growth p r e p a r e d by sac ch ar i f i c a t i o n o f corncobs v/as m i x e d w ith s u r f a c e s o i l f r o m Miami s a n d y lo a m a n d B ro o k sto n c la y lo a m a t r a t e s o f 0* 2 , £ , 5*0# a n d 7*5 t o n s per A f t e r f i v e week s? i n c u b a t i o n , t h e s o i l s w e r e acre* stu d ie d f o r changes in p h y sical,ch em ical,an d b io lo g ic a l p ro p erties* It w as fo rm atio n o f p ercen tag e in crease for f o u n d t h a t “l i g n i n ” c a u s e d a n i n c r e a s e I n t h e larg e o f m o i s t u r e a t t h e m o is tu r e e q u i v a l e n t , an in t h e hygroscopic c o e f f i c i e n t ,a n d g r e a t e r v a lu e s th e u p p e r p o in t* s ta b le ag g reg ates,an in crease in the and low er p l a s t i c l i m i t s and t h e s t i c k y P e r c e n t p o ro sity at ten sio n s, 1 0 , 2 0 , 3 0 , I|.0, a n d 6 g c e n t i m e t e r ’w a t e r was i n c r e a s e d w h e r e a s p e r c e n t c a p i l l a r y p o ro sity w as decreased* A d d itio n slig h tly th e d eterm in ed , power o f t h e ammonium a c e t a t e method* The i n c r e a s e due t o changes i n th e a c t i v i t y o r a d s o rp tiv e ' ’ i i g n i n '1 d u r i n g I t s t r a n s f o m a t i o n , 4 » r t o t h e fo rm atio n of th e b a s e exchange c a p a c ity o f th e s o i l as by was p r o b a b l y of " lig n in ” to s o il tends to in crease of c e r t a i n c o m p l e x e s * Th e b a s e e x c h a n g e c a p a c i t y ,tl i g ; n i n n m a t e r i a l u s o d was 19 m i U i e q u i v a l e n t s p o r 100 gram m a t e r i a l . The a d d itio n o n ly pH o f 1 *9 9 * o f t h e s o i l s w as s l i g h t l y i n c r e a s e d b y t h e T5l i g n i n ' 1* The pH o f th© ’’l l g n i n ” m a t e r i a l was N itra te content of th e so il,d eterm in ed co lo rim etrically b y p h o n o l d l s u l f o n l c a c i d m ethod,w as d e c r e a s e d as r a t e o f " l i g n i n " a p p l i c a t i o n i n c r e a s e d . T h i s w a s b e l i e v e d t o b e due to im m o b ilisatio n of th e n itro g e n as a r e s u l t of increased m icro b ial a c tiv ity . E x c h a n g e a b le c a l c i u m , m agn©sium(ver s e n a t e t i t r a t i o n m e t h o d ) , s o d i u m a n d p o t a s s i u m { f l a m e p h o t o m e t e r method) were n o t a f f e c t e d e x c e p t p o t a s s i u m w h i c h sh ow ed a s l i g h t in c r e a s e by " l i g n i n " a d d itio n . B u f f e r c a p a c i t y o f s o i l t r e a t e d w i t h ■l,l i g n i n tt v/as i n c r e a s e d * a l t h o u g h n o t a p p r e c i a b l y . The g r e a t e s t b u f f e r a c t i o n o f Hl i g n l n ,f l i e s b e t w e e n pH 6 , 5 - 8 . 0 , G r e e n h o u s e e x p e r i m e n t s o n s u r f a c e s o i l f r o m Miami s a n d y l o a m sh o w ed b e n e f i c i a l e f f e c t o f " l i g n i n " o n t h e y i e l d o f tom atoes and s p r in g w heat. - M itro g en ,m u lch in g , a n d l i m i n g i n c r e a s e d t h e e f f e c t i v e n e s s o f " l i g n i n ” on t o m a t o y i e l d b u t t h e l a t t e r tw o d i d n o t m a t e r i a l l y a f f e c t t h e e f f e c t i v e n e s s o f ul i g n i n n o n t h e y i e l d o f s p r u n g w h e a t. R e s u l t s o f t h e s e e-xperim ents i n d i c a t e d t h a t t h e o p t i n u m i»at e o f ,fl i g n i n M a p p l i c a t i o n w a s f i v e t o n s p e r a c r e , A c o m p a r i s o n o f c r o p y i e l d s when g r o u n d c o r n c o b s , s a w d u st, and " l i g n i n " were a p p l i e d a t f i v e to n s p e r a c r e t o s u r f a c e s o i l f r o m B r o o k s t o n c l a y loom w a s s t u d i e d u n d e r g r e e n h o u s e c o n d i t i o n s . T h e r e s u l t s sh ow ed t h a t " l i g n i n ” w a s p r e f e r a b l e t o t h e g r o u n d c o r n c o b s a n d s a w d u s t when m i x e d w i t h s o i l . When a p p l i e d a s m u l c h , " l i g n i n ” a n d g r o u n d c o rn c o b s were p r e f e r a b l e t o s a w d u st. A f i e l d e x p e r i m e n t o n M e t e a lo a m y s a n d w a s d e s i g n e d t o s tu d y t h e e f f e c t o f v a r i o u s m u lc h in g m a t e r i a l s on t h e y i e l d o f s o y b e a n s. The r e s u l t s show ed t h a t w hen no n i t r o g e n w as a d d e d , c o r n c o b s , w h e a t s t r a w , a n d s a w d u s t m u l c h i n g a l l t e n d e d t o d e c r e a s e y i e l d s . The d e p r e s s i v e e f f e c t d i s a p p e a r e d w h e n 60 p o u n d s p e r a c r e o f n i t r o g e n \*/ere a p p l i e d . An i n c r e a s e i n s o y b e a n y i e l d s w a s o b t a i n e d when n i t r o g e n was a p p l i e d a t t h e r a t e o f 1 20 a n d 180 p o u n d s p e r a e r o . I t w as t h e r e f o r e r eco m m en d ed t h a t when " l i g n i n " c o u l d be p ro c u re d a t re a s o n a b le c o s t , i t can be used t o advantage o v e r c o r n c o b s a n d s a w d u s t '//hen a p p l i e d a t f i v e t o n s p e r a c r e . N i t r o g e n a p p l i c a t i o n a l o n g w i t h Hl i g n i n " w o u l d b e b en eficial. ACKNOWLEDGEMENT The a u t h o r e x p r e s s e s h i s s i n c e r e a p p r e c i a t i o n t o D r . L . M. T u r k a n d D r . R. L . Cook f o r t h e i r g u i d a n c e i n t h e r e s e a r c h r e p o r t e d i n t h i s work and i n t h e p re p a ra tio n o f the m an u sc rip t. He a l s o w i s h e s t o t h a n k D r . A. E« E r i c k s o n , D r . K i r k L a w t o n , D r . E . P . W h i t e s i d e , D r . R, M. S w e n s o n , a n d f e l l o w s t u d e n t s o f t h e S o i l S c i e n c e D epartm ent f o r t h e i r h e l p f u l s u g g e s tio n s th ro u g h o u t th e course o f t h i s study. TABLE OP CONTENTS C hapter I II III Page INTRODUCTION. .............................. 1 REVIEW OP LITERATURE......................... 3 LABORATORY STUDIES. . . . . . . . . . . . . . . 13 A. P h y s i c a l ........................... ..........................................................l 5 1. 2. 3. ip. 5. A ggregate a n a l y s i s M oisture e q u iv a le n t . . . . H ygroscopic c o e f f i c i e n t . . R heological p r o p e r tie s . . . P o ro sity . . . . . . . . . . B. Chem ical 1. 2. 3* ip. 5. 6. 7. . . . . . . . . VI V II V III . . . . . . . . . * . . . . 15 18 18 20 23 25 Base exchangec a p a c i t y . . ........................................25 pH m e a s u r e m e n t . ....................................................... . 28 N itr a te d eterm in atio n . . . . . . . . . . 30 T o ta l and a d s o rb e d p h o s p h a te . . . . . . . 31 C a l c i u m a n d m a g n e s i u m ......................... 31 Sodium a n d p o t a s s i u m . . . . . . . . . . . 32 P u ffe r curve. .................................. 3^........................................ 35 GREENHOUSE STUDIES..............................................................................38 A. T o m a t o e s on Miami S an dy Loam . . . . . . . . 39 B . S p r i n g W h e a t on Miami S a n d y Loam . . . . . . 39 C. T o m a t o e s on B r o o k s t o n C l a y Loam. Ipip . . . . . . D. S p r i n g W h e a t on B r o o k s t o n C l a y Loam. V . . . . .................................................. C. B i o l o g i c a l IV . . . . . . . . FIELD S T U D I E S ....................... .. SUMMARY ....................................................... CONCLUSIONS LITERATURE CITED. 1+7 . . . . . . . . ............................................... . . . Ipip 50 52 ............................................................. 53 I. INTRODUCTION The e x a c t c h e m i c a l a n d p h y s i c a l s t r u c t u r e o f l i g n i n and t h e p r o d u c t s fo rm ed by i t s kno w n . T h is I s due l a r g e l y t o t h e d i f f i c u l t y i n v o l v e d i n is o la tin g lig n in in I ts fore, decom position a re n o t w e ll c h em ically unchanged form . There­ a d i s t i n c t i o n s h o u l d b e made b e t w e e n two t y p e s o f l i g n i n : 1 , u n a l t e r e d l i g n i n w hich o c c u rs i n l i v i n g p l a n t s or tre es, and 2 . a l t e r e d l i g n i n d e r i v e d from p l a n t s and t r e e s by chem ical o r b i o l o g i c a l a c t i o n s . m a te ria l used in th is Crude l i g n i n , its study b elongs to th e d eriv ativ es, The l i g n i n second type* and l i g n i n - l i k e m a t e r i a l s a r e d i s c h a r g e d b y p a p e r m i l l s i n enormous q u a n t i t i e s . d i s p o s a l o f l i g n i n p o s e s a problem t h a t o f f e r s t o p a p e r m a n u f a c t u r e r s and a g r i c u l t u r i s t s . The a challenge The p a p e r m a n u f a c t u r e r m u s t d i s p o s e o f t h e l i g n i n w i t h a minimum p o l l u t i o n to the stream t h a t f u rn is h e s w a te r f o r h is p l a n t . T h i s m e a n s t h a t some o f t h e o r g a n i c m a t e r i a l may b e de co m ­ p o s e d w i t h o u t s e r v i n g any u s e f u l p u r p o s e 0 F a rm e rs to o have l a r g e amounts o f l i g n i n - c o n t a i n i n g m ateria ls s u c h a s c o r n c o b s an d s t r a w s w h i c h c o u l d , b y p r o p e r m a n a g e m e n t , be com e v e r y u s e f u l i n i m p r o v i n g s o i l p r o p e r t i e s and crop y i e l d . D u r i n g r e c e n t y e a r s , many a g r i c u l t u r i s t s h a v e made 2 s t u d i e s on t h e p o s s i b l e u s e o f l i g n i n f o r s o i l i m p r o v e m e n t an d f o r t h e b e t t e r m e n t o f p l a n t g r o w t h * n o t always agreed* T h e ir r e s u l t s have Some w o r k e r s c l a i m e d t h e p r o d u c t s w e r e b e n e f ic ia l w h ile o th e rs r e p o rte d o p posite r e s u l t s . The p r i n c i p a l o b j e c t i v e o f t h i s i n v e s t i g a t i o n was t o s tu d y t h e e f f e c t o f l i g n i n on t h e p h y s i c a l , chem ical, b io lo g ic a l p r o p e r t i e s o f the s o i l as w e ll as i t s p l a n t grow th u n d e r g re e n h o u se c o n d itio n s # and e f f e c t on ri. REVTEW OF LITERATURE L i t e r a t u r e on t h e e f f e c t o f l i g n i n on s o i l p r o p e r t i e s and p l a n t g ro w th c a n be d i v i d e d i n t o s e v e r a l c a t e g o r i e s : 1, I t s use as a f e r t i l i z i n g m a te r ia l; conditioner; 3« I ts 2, I t s use as a s o il r e la tio n s h ip w ith s o il organic m atter and s o i l c h e m ic a l p r o p e r t i e s ; a n d ij.. I t s d ecom position i n so il. L ig n in as a F e r t i l i z i n g M a te r ia l A ries (I4.) f o u n d t h a t G a - l i g n o s u l f o n a t e f r o m s u l f i t e w aste l i q u o r , a p p lie d a t th e r a t e o f te n tons p e r a c re , c a u s e d a 60 p e r c e n t i n c r e a s e i n t h e y i e l d o f s h e l l e d b e a n s # He a l s o f o u n d t h a t t h e u s e o f l i g n i n f r o m d i l u t e a c i d h y d r o l y s i s i n c r e a s e d t h e s t a r c h c o n t e n t o f p o t a t o e s by 85 p e r c e n t # Dunn a n d S i e b e r l i c h (19) found i n t h e i r greenhouse e x p e r i m e n t s t h a t p o t a t o e s w e r e somewhat i m p r o v e d b y an a p p lic a tio n of f iv e tons of l i g n i n p e r a c re . O n i o n s (one t e s t ) w ere m a r k e d ly im proved b u t to m ato y i e l d s were n o t affected . Almost com plete e x h a u s t i o n o f a v a i l a b l e n i t r a t e s was n o t e d i n a l l s o i l s t o w h i c h l i g n i n was a d d e d . resu lts, in a lim ite d s e rie s of t e s t s , sand c u l t u r e s t h a n i n w a t e r c u l t u r e s , divided s ta te B etter were s e c u r e d i n L ig n in in the f in e ly a d h e r e s i n c o n s i d e r a b l e amount t o t h e f i n e ro o tle ts of seed lin g s. The y s u g g e s t e d t h a t l i g n i n when k a d d e d t o t h e s o i l m i g h t h a v e a r o l e w i t h o t h e r humus c o n ­ s t i t u e n t s i n f o r m i n g an i n t i m a t e f i l m a b o u t s o i l p a r t i c l e s a n d r o o t h a i ‘£ s w h i c h a i d i n t h e t r a n s f e r o f w a t e r a n d s o i l n u tr ie n ts to the ro o t c e lls# Waksman a n d W i s s e n ( 7 1 ) s u g g e s t e d t h e p o s s i b l e u s e o f l i g n i n a s a n u t r i e n t f o r t h e c u l t i v a t e d m ush room , A g a r i c u s cam pestris. The r e s e a r c h w o r k e r s a t t h e F o r e s t P r o d u c t s L a b o r a ­ tory, (26) u s i n g " l i g n i n ” o b t a i n e d from a c i d h y d r o l y s i s , f o u n d t h a t t o m a t o p l a n t s grown i n s o i l r e c e i v i n g b o t h lig n in ( fiv e tons p er acre) an d f e r t i l i z e r w e r e mor e v i g o r ­ o u s a n d b o r e m o re f r u i t s t h a n w h e r e o n l y f e r t i l i z e r was applied. The p l a n t s i n t h e p l o t w h i c h r e c e i v e d l i g n i n a n d no f e r t i l i z e r w e r e h e a l t h y an d b o r e g o o d f r u i t , but y ields w ere s m a l l e r t h a n from t h e p l o t s r e c e i v i n g f e r t i l i z e r a l o n e 0 Dunn an d E p p e l s h e i m e r ( 2 6 ) t e s t e d t h e e f f e c t o f l i g n i n o b t a i n e d f r o m wood s a c c h a r i f i c a t i o n on p o t a t o p r o d u c t i o n . Thin l a y e r s o f l i g n i n were a p p l i e d betw een l a y e r s o f s o i l a t a r a t e eq u iv a le n t to fiv e tons p e r a c re . show ed t h a t l i g n i n i n c r e a s e d t h e y i e l d , The r e s u l t s s i z e and s t a r c h co n ten t o f the tubers# H arrington ( 2 6 ) r e p o r t e d t h a t c h r y s a n t h e m u m s grown i n s o i l s t o w h i c h 10 p e r c e n t o f l i g n i n h a d b e e n a d d e d p r o ­ d u c e d l o n g e r s t e m s an d b o r e l a r g e r b lo o m s t h a n d i d t h e c o n tro l plants# Th e s t e m w e i g h t w a s i n c r e a s e d b y 30 p e r c e n t # 5 L ig n in as a S o i l C o n d itio n e r V ershinin (61), Sowden a n d A t k i n s o n t h a t l i g n i n ., wh en i n c o r p o r a t e d i n s o i l , (Sk) reported e x e rte d favorable e f f e c t s on t h e p h y s i c a l s t r u c t u r e o f s o i l # M i l l e r (38) showed t h a t l o a d - b e a r i n g q u a l i t i e s o f some s o i l s w e r e i m p r o v e d b y m i x i n g l i g n i n o r a s u b s t a n ­ t i a l l y w a t e r i n s o l u b l e l i g n e o u s m a t e r i a l w i t h them . S oils which h a d p o o r r e s i s t a n c e to m o i s t u r e e f f e c t s were s t a b i l ­ i z e d i n t h e same m a n n e r # D ep en d in g on t h e n a t u r e o f t h e so il, 0»2 t o 1 0 p e r c e n t o f l i g n e o u s m a t e r i a l w as r e q u i r e d , b u t t h r e e p e r c e n t o r l e s s was p r e f e r r e d # M cC alla (33) fou n d t h a t w a x e s, f a t s and l i g n i n s i n c o n c e n t r a t i o n s o f one p e r c e n t o r m o re g r e a t l y s t a b i l i z e d so il p a rtic le so M a r t i n a n d Waksman ( 3 6 ) f o u n d t h a t i n m o i s t c l a y lo am so il, c a s e in p lu s l i g n i n brought about c o n sid e ra b le aggre­ g a t i o n , w hich was f u r t h e r i n c r e a s e d by t h e a d d i t i o n o f lim e# The a g g r e g a t i o n w as n o t so a p p a r e n t a f t e r t h e s o i l dried# The y a l s o r e p o r t e d t h a t p e a t p l u s l i g n i n d i d n o t m a t e r i a l l y in flu e n c e th e a g g re g a tio n o f the s o i l , N i k i s h k i n a (if2 ) f o u n d t h a t a m m o n i a t e d l i g n i n i n c r e a s e d th e s tr u c tu r a l s ta b ility of 3, 2, and 1 m i l l i m e t e r a g g r e ­ gates# H arris (26) in d ic a te d th a t w ood-hydrolysis lig n in , when u s e d a s a m u l c h b e t w e e n r o w s o f t o m a t o e s , m o i s t a n d was e a s i l y w o r k e d i n t o t h e s o i l . kept the s o il 6 H a m i l t o n an d T r u o g ( 2 6 ) t e s t e d t h e u s e o f l i g n i n i n both f i e l d and g re e n h o u se . The y f o u n d t h a t a d d i t i o n s o f lig n in r e s u lte d in a g re a te r ease of c u ltiv a tio n . holding c a p acity , p o ro s ity , so il, W ater r a t e c f w a te r flow th ro u g h the and s o i l h a r d n e s s were a ls o im proved. I t was f o u n d t h a t th e b e n e f i c i a l e f f e c t s co n tin u e d through s e v e ra l c ro p s. ITine m o n t h s a f t e r t h e a d d i t i o n o f l i g n i n t o a s o i l , an i n c r e a s e o f i n f i l t r a t i o n by A r ie s r a t e up t o 1 0 0 - f o l d was f o u n d (5)» L ig n in - - a 3 R e la te d w ith S o il O rganic M a tte r and Chem ical P r o p e r t i e s o f S o i l N e l l e r a n d K e l l y (I4I ) content of s o il s lig n in . showed t h a t t h e o r g a n i c m a t t e r c o u l d b e i n c r e a s e d b y m ea ns o f w a s t e wood T his o r g a n ic m a t t e r was, by v i t r u e o f i t s h ig h content of lig n in , tu re , m oisture, qu ite s t a b l e even though th e te m p e ra ­ and a e r a t i o n c o n d i t i o n s w ere c o n d u c iv e t o l o s s by o x i d a t i o n th r o u g h o u t most o f th e y e a r . Under p r o p e r s o i l management i n t h e u s e o f l i m e , l i g n i n - t r e a t e d s o i l s w e r e m ore p r o d u c t i v e . n eu tral These w r i t e r s also re p o rte d th a t a n d n e u t r a l i z e d wood w a s t e l i g n i n s r e t a r d e d t h e l o s s by l e a c h i n g o f f e r t i l i z e r p h o s p h a te from sandy s o i l s . Sowden a n d A t k i n s o n (5>£) p o i n t e d o u t t h a t l i g n i n i s o l a t e d f r o m s o i l was d i f f e r e n t f r o m p l a n t l i g n i n i n many resp ects. I t w a s v e r y lo w i n m e t h o x y l c o n t e n t , h i g h i n to ta l n itrogen, so lu b le in w ater, b u t in s o lu b le In d ilu te acid. t h e u l t r a - v i o l e t l i g h t a b s o r p t i o n c u r v e was However, 7 s i m i l a r i n many r e s p e c t s t o t h a t o f l i g n i n a n d r e l a t e d compounds« Prom t h e r e s u l t s o f h y d r o g e n a t i o n o f " a l k a l i l i g n i n " , G o t t l i e b an d H e n d r i c k s (25) indicated th a t lig n in in so il undergoes a s im i l a r ty p e of change, a t a much s l o w e r r a t e , as d o e s l i g n i n t r e a t e d w i t h a l k a l i . The c h a n g e c o n s i s t s o f a c o n d e n s a tio n o f th e l i g n i n m olecule w ith th e p r o d u c tio n of f u s e d r i n g s t r u c t u r e s w h i c h a r e m o re r e s i s t a n t t o h y d r o - genoly sis th an is the u n a lte re d lig n in . H arris (26) p o i n t e d o u t t h a t l i g n i n i s s lo w ly changed t o h u m i c s u b s t a n c e s wh en m ix e d * .w it h s o i l . i s c o n v e r t e d t o humus, Even b e f o r e i t i t h a s many p r o p e r t i e s o f humus, such a s t h e a b i l i t y t o r e a c t w i t h m i n e r a l s i n t h e s o i l , c o n tro l the s iz e of aggregates in clay , to and t o a i d i n c o n ­ t r o l l i n g the a l k a l i n i t y of s o i l . E v id e n c e o f the' p r e s e n c e o f l i g n i n i n s o i l o r g a n i c m atter, a c c o r d i n g t o B e r t r a m s o n a n d W h it e ( 1 3 ) » r e s t s on r e s u l t s from d e c o m p o s itio n s t u d i e s , on r e s i s t a n c e t o 50 p e r c e n t o r more o f o r g a n i c m a t t e r t o acids, cold s tro n g and on t h e p r e s e n c e o f m e th o x y l g r o u p s . found t h a t g r e a t e r a l k a l i p a r t i a l dem ethylation, o f 30 The y a l s o s o l u b i l i t y and exchange c a p a c i t y , p o s s ib le in tr o d u c tio n of carboxyl g r o u p s an d d e p o l y m e r i z a t i o n r e s u l t e d f r o m c h a n g e s w h i c h l i g n i n had undergone in s o i l . M illar, S m i t h a n d Brown ( 3 7 ) a g r e e d w i t h McGeorge (3l+)> B a r t l e t t a n d Herman ( 9 ) t h a t d u r i n g t h e d e c o m p o s i t i o n o f o rg an ic.m atter, th ere is a highly s ig n ific a n t c o rre la tio n 8 b e tw e e n p e r c e n t i n c r e a s e i n b a s e ex change c a p a c i t y and t h e amount o f l i g n i n i n s o i l s . But s i n c e t h e i n c r e a s e i n t h e b a s e h o l d i n g p o w e r was so much g r e a t e r t h a n t h e i n c r e a s e in th e lig n in co n ten t, in the a d s o rp tiv e i t h as b e e n s u g g e s te d t h a t a change cap acity or a c t i v i t y of the lig n in had taken p la c e . McGeorge ( 3 5 ) r e p o r t e d t h a t t h e e x c h a n g e c a p a c i t y o f s o il l i g n i n is not a c o n sta n t q u a n tity bu t v a r ie s in d i f f e r ­ ent s o ils . L each in g th e l i g n i n and lig n o -h u m a te w ith w a te r i n c r e a s e d t h e e x c h a n g e c a p a c i t y w h i c h h e b e l i e v e d was dixe to h y drolysiso A n d e r s o n (3) claim ed t h a t th e exchange c a p a c ity o f t h e s u l f i t e w a s t e l i q u o r d e p e n d s on t h e s u l f o n i c a c i d g r o u p s in th e l i g n i n m olecule. Under th e e x p e rim e n ta l c o n d i t i o n s , t h e maximum c a p a c i t y o f t h e e x c h a n g e r s d i d n o t e x c e e d a v a lu e o f 0 .6 m i l l i e q u i v a l e n t p e r m i l l i l i t e r o r 1 .2 0 m i l l i e q u i v a l e n t p e r gram. Waksman an d I y e r (68) fo u n d t h a t l i g n i n a lo n e h a d a low b a s e ex change c a p a c i t y . The b a s e e x c h a n g e c a p a c i t y o f p r o t e i n w as lo w b u t so mew ha t h i g h e r t h a n f o r l i g n i n . When t h e two w e r e c h e m i c a l l y c o m b i n e d i n t h e f o r m o f a c o m p l e x , t h e b a s e e x c h a n g e c a p a c i t y w as g r e a t l y i n c r e a s e d . p r o p o r t i o n o f p r o t e i n t o l i g n i n was i n c r e a s e d , the base exchange c a p a c i t y i n c r e a s e d w i t h i n c e r t a i n l i m i t s . v a r io u s p r o t e i n s gave d i f f e r e n t v a lu e s , r e l a t i o n s h i p s wer e, s i m i l a r . As t h e The b ut the general D ry in g th e com plexes re d u c e d t h e i r base exchange c a p a c i t i e s t o some e x t e n t . The n a t u r e 9 o f t h e b a s e u s e d i n p r e p a r i n g t h e com plexes a l s o t h e i r b ase exchange c a p a c i t i e s co n sid erab ly . in flu en ced The h i g h e s t b a s e exchange c a p a c i t i e s w ere o b t a i n e d w ith Ca-com plexes and t h e l o w e s t w i t h alu m in u m -c o ra p le x e s* B a r t l e t t a n d Norman ( 9 ) found t h a t th e m agnitude o f t h e i n c r e a s e d b a s e e x c h a n g e c a p a c i t y o b s e r v e d o n decompo­ s i t i o n o f l i g n i n w as e n t i r e l y d i s p r o p o r t i o n a t e w i t h t h e lim ite d dem ethylation t h a t o ccu rred . A ries (Ij.) f o u n d t h a t a p p l i c a t i o n o f s u l f i t e s o i l i n p o t s i n c r e a s e d t h e o r g a n i c c o n t e n t , pH, phosphorus, and c a lc iu m c o n t e n t o f t h e s o i l . m entioned t h a t s u l f i t e l i g n i n l ig n in to so lu b le He a l s o co u ld be u sed as a s u b s t i t u t e f o r l im i n g m a t e r i a l s and t h a t t h e p r e v e n t i o n o f l e a c h i n g was an a d d e d a d v a n t a g e . N i k i s h k i n a (if2 ) , Waksman a n d H u t c h i n g s Honcamp a n d W i e s s m a n n ( 2 8 ) a l l ( 6£ ) , and agreed t h a t lig n i n has the t e n d e n c y t o p r e s e r v e t h e a b s o r b e d ammonium n i t r o g e n o f t h e s o i l a n d t h e ammonia i n l i q u i d m a n u r e 0 L ignin - - I t s D ecom position i n S o il Waksman a n d I y e r ( 6 7 ) a n d O s u g i a n d Endo observed t h e d e p r e s s i v e e f f e c t o f l i g n i n on t h e d e c o m p o s itio n o f p ro te in . The e f f e c t , t h e y c l a i m e d , w a s n o t du e t o a n y t o x i c a c t i o n o f l i g n i n b u t was a r e s u l t o f i n t e r a c t i o n betw een l i g n i n and p r o t e i n . Waksman a n d C o r d o n ( 6ij.) a n d P u l l e r an d Norman ( 2 3 ) f o u n d s i m i l a r d e p r e s s i v e e f f e c t s c e l l u l o s e decom position. in The y a t t r i b u t e d t h i s t o t h e p h y s i c a l 10 b i n d i n g t o g e t h e r o f l i g n i n and c e l l u l o s e . an d S h e r r a r d (ijlj.) an d L e v i n e a n d o t h e r s hand, O lson, P e te r s o n (32), on t h e o t h e r cla im e d t h e b in d in g to be o f a chem ical r a t h e r th an a phy sical n a tu re . B ennett corn s t i l a g e , (12) stu d y in g th e decom position o f o a t hay, t i m o t h y h a y a n d c o r n s t a l k s w i t h an d w i t h o u t t h e a d d i t i o n o f 13 p e r c e n t l i g n i n fo u n d t h a t u n d e r c e r t a i n c o n d i t i o n s t h e p r e s e n c e o f l i g n i n was n o t i n h i b i t o r y . Waksman a n d T e n n e y ( 7 0 ) p o i n t e d o u t t h a t l i g n i n s a r e m or e r e s i s t a n t t o t h e a c t i o n s o f f u n g i an d b a c t e r i a t h a n a re any o f th e o t h e r m ajo r i n g r e d i e n t s o f t h e n a t u r a l organic m a te r ia ls . The a c c u m u l a t i o n o f l i g n i n i n s o i l i s b e l i e v e d b y them t o a c c o u n t f o r a l a r g e p a r t o f s o i l humus, Waksman a n d H u t c h i n g s (6 6 ) summarized t h e a c c u m u la te d evid en ce c o n c e rn in g th e a c t i o n o f m icroorganism s upon l i g n i n , i n t h e p r o c e s s o f d e c o m p o s itio n o f p l a n t and anim al r e s i ­ dues i n n a t u r e as f o ll o w s : 1, L ignin is , among c h e m i c a l c o m p l e x e s , m o s t r e s i s t a n t ‘ t o a t t a c k by f u n g i, b a c t e r i a and i n v e r t e b r a t e anim als l i v i n g i n s o i l s , p e a t bogs and com posts, 2 . L ig n in does n o t accum ulate q u a n t i t a t i v e l y i n the same s t a t e i n w h i c h i t e x ists in p la n t m ateria ls b u t u n d e r g o e s a slow p r o c e s s o f t r a n s f o r m a t i o n * 3* C e r t a i n s p e c i f i c g r o u p s o f m i c r o o r g a n i s m s , l a r g e l y among t h e h i g h e r f u n g i , found are capable o f b rin g in g about a c tiv e d e s tr u c tio n o f l i g n i n , q u e n tly even to a g reater- e x te n t th a n t h a t o f fre-. cellu lo se i+o L i g n i n i s and h e m ic e llu lo s e . s u b j e c t to d e c o m p o s i t i o n b y t h e s e o r g a n ­ i s m s so l o n g a s i t is present in fresh or in p a rtly decomposed p l a n t t i s s u e s ; p u rified sta te , attack once i t is prepared in a i t becomes c o m p l e t e l y r e s i s t a n t t o even by t h e s e organism s* 5>« The e f f e c t o f l i g n i n u p o n m i c r o b i a l a c t i v i t i e s , such as c e l l u l o s e decom position, t a t i o n and n i t r a t e form ation, glucose ferm en­ i s n o t i n j u r i o u s and may e v e n b e f a v o r a b l e , 6 , The g r a d u a l t r a n s f o r m a t i o n o f t h e l i g n i n c o n s i s t s i n a, a l o s s o f m ethoxyl groups b , darkening i n c o lo r, a c c o m p a n i e d by a b s o r p t i o n o f oxygen c , com b in atio n w ith p r o t e i n d, increase in a lk a li s o lu b ility A lth o u g h l i g n i n i s r e s i s t a n t t o a t t a c k by m i c r o o r g a n ­ ism s, it does n o t p o s s e s s a n t i s e p t i c p r o p e r t i e s ( 5 3 )* Tt w i l l decompose g r a d u a l l y w i t h t h e r a t e o f d e c o m p o s it i o n d e p en d in g upon e n v ir o n m e n ta l c o n d i t i o n s ( 9 , i+7 )» Norman (1+3) f o u n d t h a t u n d e r a e r o b i c c o n d i t i o n s a n d in s itu lig n in is q u ite sta b le , but undergoes a s l i g h t d e c o m p o s itio n d u r in g f e r m e n t a t i o n e x t e n d i n g o v e r months o r years. Fungi o f th e B asidiom ycetes type slow ly a tta c k l i g n i n as w e l l as c e l l u l o s e and t h e h e m i c e l l u l o s e . anaerobic c o n d itio n s , m esophilic lig n in is Under s lo w ly a t t a c k e d by b o t h and t h e r m o p h i l i c o rg a n ism s, but to a l e s s e r 12 e x te n t than are o th e r p la n t c o n s titu e n ts , Iso lated lig n in i s n o t a t t a c k e d by a e r o b i c and a n a e r o b i c m ic ro o r g a n is m s and a p p a r e n t l y h a s a d e f i n i t e b a c t e r i o s t a t i c a c tio n ,. P u l l e r a n d Norman ( 2 3 ) f o u n d t h a t t h e e x t e n t o f decom­ p o s i t i o n a c c o m p lis h e d by t h e v ig o r o u s .organism s, Pseudo­ monas e p h e m e r o c y a n e a , and S p o r o c y to p h a g a m y x o c o c c o id e s , i n c r e a s e d a s t h e l i g n i n c o n t e n t w as r e d u c e d . Less vigorous o rg an ism s such as B a c i l l u s apporhoeus were l i t t l e affected by t h e l i g n i n c o n t e n t o f t h e s u b s t r a t e , F i s c h e r a n d S c h r a d e r '■(22) showed t h e r e l a t i v e b i o l o g i c a l in ertn e ss of lig n in , an d c o n c l u d e d t h a t l i g n i n was t h e r e f o r e th e "m other s u b sta n c e " o f r e s i d u a l s o i l o rg a n ic m a t t e r , G o t t l i e b a n d G e l l e r ( 2 i+) f o u n d t h a t l i g n i n c o u l d be d e c o m p o s e d b y u s i n g c o m m e r c i a l mushroom spawn a s a n enzyme w h ich i s an i n t i m a t e m i x t u r e o f mycelium o f A g a ric u s c a m p e s t r i s and w e l l decomposed h o r s e m anure. was a c t i v a t e d b y c i t r a t e The enzyme and p h o sp h a te io n s and b u f f e r e d t o pH 6-.0. Denkho ( 18) c l a im e d t h a t l i g n i n decomposes f a s t e r i n a n a c i d medium t h a n i n a n e u t r a l o r a l k a l i n e med iu m. lig n in is As decomposed m ic ro o r g a n is m s im m o b iliz e n i t r o g e n , B artlett, S m i t h a n d Brown ( 1 0 ) b e l i e v e d t h a t t h e r e w as some s o r t o f d i r e c t c h e m i c a l p r o c e s s w h i c h b r o k e down the o r ig in a l " n a tu ra l lig n in " into a more r e a d i l y a v a i l a b l e form b e f o r e a c t i v e m i c r o b i o l o g i c a l d e c o m p o s itio n s e t i n . I ll. LABORATORY STUDIES M a t e r i a l u s e d and p r o c e d u r e : The l i g n i n u s e d i n t h i s i n v e s t i g a t i o n was r e c e i v e d from A g r i c u l t u r a l R e s id u e s D i v i s i o n , N o rth R e g io n a l R e s e a r c h L aboratory, U. S . D. A . , P e o r i a 5> I l l i n o i s . The l i g n i n w hich had b een p r e p a r e d by s a c c h a r i f i c a t i o n o f corncobs was n o t a s f r e e f r o m c a r b o h y d r a t e s a s was a n t i c i p a t e d . I f t h e work on t h e s a c c h a rific a tio n process is continued, th e y b e lie v e t h a t th e carb o h y d rate m a te r ia l can be reduced, but i t w i l l not be e n t i r e l y e lim in a te d . T a b l e 1 shows t h e p roxim ate a n a l y s is o f th e l i g n i n u se d . The s o i l s u s e d i n t h i s s tu d y were s u r f a c e sam ples o f Miami s a n d y l o a m a n d B r o o k s t o n c l a y l o a m s o i l s . The pH o f t h e two s o i l s was f o u n d t o b e 6 , 5 2 by Beckman pH m e t e r . F o r c o n v e n ie n c e t h e s e s o i l sam ples a r e r e f e r r e d to by th e s o i l t y p e nam es t h r o u g h o u t t h i s t h e s i s . T h r e e l e v e l s o f " l i g n i n ” w e r e a p p l i e d t o t h e two so ils &s f o l l o w s : L 0 0 tons p e r acre L 2 .5 2.5 tons p er acre L 5.0 5 .0 to n s p e r acre L 7*5 7*5. t o n s p e r a c r e E a c h t r e a t m e n t was r e p l i c a t e d f o u r t i m e s , m a k i n g a t o t a l o f 32 p o t s . Ik TABLE 1 PROXIMATE ANALYSIS OP "LIGNIN” PRODUCED BY SACCHARIFICATION OF CORNCOBS IN SYNTHETIC LIQUID FUELS SEMI-WORKS PLANT, PEORIA, IL L IN O IS . JUNE, 1 9 ^ 0 Percent L ignin ij-2,33 C ellulose M onoethanolam ine m ethod ( p e n t o s a n f r e e ) A lp ha-cellulose (pentosan free) ij.2,10lij.«20 A lcohol-benzene e x tr a c tio n s 13*74- Pentosans T itratab le 3*57 acid ity A lkali s o lu b ility ( a s SO^) 0.86 ( 1 % NaOH) 66.27 M ethoxyl 6.37 M oisture 6.70 N (K jeldahl) 0.23 Ash 0.87 15 One t h o u s a n d g r am s o f s o i l a n d 11l i g n i n ” o f t h e v a r i o u s r a t e s w ere w e l l m ix ed and p u t i n t o h a l f - g a l l o n p o t s . The m o i s t u r e c o n t e n t o f e a c h p o t w as m a i n t a i n e d a t a p p r o x i m a t e l y m oisture e q u iv a le n t w ith d i s t i l l e d w a te r. th e s o i l s were a i r d r i e d . A f t e r f i v e weeks, F i f t y g r am s o f t h e a i r d r y s o i l was s a m p l e d f r o m e a c h p o t f o r a g g r e g a t e a n a l y s i s , w h i l e t h e r e m a i n i n g s o i l w a s p a s s e d t h r o u g h a two m i l l i m e t e r siev e f o r la b o ra to ry U nless stu d ies. otherw ise s ta te d , a l l th e fig u re s re p o rte d in the ta b le s h e r e in are averages of fo u r r e p lic a tio n s * E xperim ental: A. P h y s i c a l (1 ) A g g r e g a t e a n a l y s i s F i f t y gram s o f a i r d r y s o i l was u s e d f o r a g g r e g a t e a n a l y s i s a c c o r d i n g t o Y o d e r’ s w e t s i e v i n g method (7W ) * The p e r c e n t a g e o f a g g r e g a t e s a s a f f e c t e d b y " l i g n i n ” t r e a t m e n t a t v a r i o u s r a t e s a r e shown i n T a b l e s 2 a n d 3 , The e f f e c t o f " l i g n i n ” on t h e p e r c e n t a g e o f a g g r e ­ g a t e s g r e a t e r t h a n 0 * 2 5 mm i s in F igures I I t can of "lig n in " shown b y t h e c u r v e s p r e s e n t e d and II* be s e e n from T a b le s 2 and 3 t h a t t h e a d d i t i o n to th e s o il in c re a se d ag gregation co n sid erab ly . S i n c e i t w as s u g g e s t e d b y T i u l i n (57) t h a t o n l y t h o s e a g g r e ­ g a t e s l a r g e r t h a n 0* 25 mm a r e r e s p o n s i b l e f o r s t a b l e stru ctu re, s p e c i a l a t t e n t i o n was g i v e n t o t h o s e a g g r e g a t e s * 16 TABLE 2 AGGREGATE ANALYSIS OP MIAMI SANDY LOAM SOIL TREATED WITH DIFFERENT RATES OF nLI'GNINn P a rtic le size mm T reatm ents p erc en tag e of t o t a l w eight L 0 L 2,5 L 5.0 L 7.5 5 .2 2 “ 6 «81| 9»i|-6 3.32 4«60 3*48 4 .64 8.74 3.58 5.76 4*18 5.22 0.^-1 o 025 - o » 5 7.98 23.76 8.30 24*24 8,98 22,10 8.22 2 2 .7 6 0 , 105- 0 ,2 5 2^ * 5 6 20.04 2 3*82 22.48 30.56 32.46 2 7 .0 2 27 068 >4 2-i*. 1-2 c 0 ,1 0 5 ‘“‘A v e r a g e o f t h r e e r e p l i c a t i o n s TABLE 3 AGGREGATE ANALYSIS OF BROOKSTON CLAY LOAM SOIL TREATED WITH DIFFERENT RATES OF “LIGNIN” P article mm size >4 2-4 1-2 o ,5 -1 0 ,2 5 - 0 ,5 0 , 105- 0 .2 5 < 0 .1 0 5 Treatm ents p e rc e n ta g e o f t o t a l w eight L 5.0 L 0 L 7*5 L 2.5 3 .1 4 3 .9 6 5 .2 8 1 0 .4 2 2 4 .1 8 2 4 .8 6 28,16 3.24 4.36 10*44 5.24 6.92 6 .2 6 5.80 7 *66 1 2 .7 8 2 4 .1 4 7.66 1 2 .1 4 22,72 16.94 24.30 1 0* 9 4 22.34 22.68 28,64 25*74 19.06 F i g u r e ;I.: F f f e in co : ?pepa' f£cjnF o n ;;a g g r e g a t i o n s a n d v loam ; S gu in c o on a to n loam *1 L L5 . 6 O L S .o Pe b e n t a v a i l a b l e r e a t d a v ith ^d i ? f e r e n t lig ri L o L2.5 LS.O 175 Miam3 s m e y lo;on L%5 Brool st'o n L S .O loam Llg n in 17 As shown i n F i g u r e s I and I I , the p ercen t aggregates g r e a t e r t h a n 0 . 2 5 mm i n c r e a s e d w i t h t h e r a t e o f " l i g n i n " ap p licatio n . This a g re e s w ith th e r e s u l t s r e p o r te d by N i k i s h k i n a (ij.2 ) . I t has been u n iv e r s a lly agreed th a t th e s o i l c o llo id a l m a te r ia l i s r e s p o n s ib le f o r th e cem en tatio n o f prim ary p a rtic le s in to sta b le aggregates. T he s o i l c o l l o i d s may b e d i v i d e d i n t o a t l e a s t t h r e e d i s t i n c t g r o u p s so f a r a s t h e i r cem entation e f f e c t s a re concerned. p artic le s them selves, in o rg an ic c o llo id s , T he y a r e c l a y i r r e v e r s i b l e o r slow ly r e v e r s i b l e and o r g a n ic c o l l o i d s . As i s o l a t e d l i g n i n i s g e n e r a lly c o n sid e red to be of c o l l o i d a l n a tu re and s in c e i t p o s s e s s e s a d s o r p t i v e p r o p e r t i e s ( £ , 1 9 ).■. i t i s b e l i e v e d t h a t l i g n i n i t s e l f may i n o n e way o r a n o t h e r b ind the s o il p a r t i c l e s aggregate fo rm atio n . unknown. It to g e th e r to b rin g about in c re a se d The n a t u r e o f b i n d i n g i s , however, c o u ld be a p h y s i c a l o r c h em ical l i n k a g e o r a co m b in atio n o f th e tw o. S i n c e e x p e r i m e n t s h a v e shown t h a t i s o l a t e d l i g n i n shows g r e a t a f f i n i t y f o r p o s i t i v e l y ch arg ed b a s i c dye, it a n eg ativ e charge. is apparent th a t lig n in possesses This s u g g e s ts t h a t t h e l in k a g e betw een s o i l a n d l i g n i n i s more o f a c h e m i c a l t h a n p h y s i c a l n a t u r e sin ce clay p a r t i c l e s It are a ls o n e g a tiv e ly charged. i s known t h a t m i c r o b i a l p r o d u c t s t e n d t o c e m e n t so il p a rtic le s . ( s e e Table 1 2 ) , S ince l i g n i n prom otes m ic r o b ia l a c t i v i t y t h e r e i s a p o s s i b i l i t y t h a t th e improved a g g r e g a t i o n may b e i n d i r e c t l y due t o o r g a n i s m a c t i v i t y . 18 (2) M o is tu re e q u i v a l e n t T h ir ty -g r a m sam ples o f a i r dry s o i l w ere used f o r m oisture e q u iv a le n t d e te rm in a tio n s. of the o r ig in a l m a te ria l Only 10-gram sam ples ( ’’l i g n i n ” ) w e r e u s e d due t o t h e bulkiness of t h i s m a te ria l. B r i g g s and M cLane's m ethod ( 1 6 ) w h i c h d e f i n e s t h e t e r m ’’m o i s t u r e e q u i v a l e n t ” a s t h e am ount o f w a t e r h e l d b y s o i l a g a i n s t a f o r c e 1 00 0 t i m e s g rav ity ( e q u i v a l e n t t o t h e c e n t r i f u g a l f o r c e a t 2ljli0 rpm f o r 30 m i n u t e s ) was u s e d . equivalent is It The p e r c e n t m o i s t u r e a t m o i s t u r e shown i n T a b l e L|.» i s known t h a t a d d i t i o n o f o r g a n i c m a t t e r " t o so il in c re a se s th e p e rc e n t m oisture a t m oisture e q u iv alen t since o rg an ic m a tte r h as a high w ater h o ld in g c a p a c ity . L i k e w i s e i t may r e s u l t i n a h i g h e r w i l t i n g p o i n t . a d d itio n of l i g n i n to s o il gives r e s u l t s s im ila r to those o b t a i n e d from a d d i t i o n o f o r g a n i c m a t t e r . T a b l e s I4. a n d The As i n d i c a t e d i n t h e r e was a d e f i n i t e t r e n d tow ard i n c r e a s e d m o istu re percentages* a t b o th m o i s t u r e e q u i v a l e n t and hygroscopic c o e f f i c i e n t , w ith in c re a se d a p p lic a tio n s of ’’l i g n i n ” . It s m a l l whe n i t i s not s u r p r is in g th a t the in c re a se s are i s remembered t h a t a f i v e t o n a p p l i c a t i o n i s eq u al only to 0 o$ p e rc e n t of the s o il. (3) H y g r o s c o p ic c o e f f i c i e n t Ten-gram sam ples o f a i r d r y w o i l were w eighed, dried , and rew eig h ed . The p e r c e n t m o i s t u r e d r y s o i l b a s i s ) was c a l c u l a t e d a n d i s oven- (on t h e oven- shown i n T a b l e f?» 19 TABLE !(. PERCENT MOISTURE OF SOILS TREATED WITH DIFFERENT RATES OF "LIGNIN” AT MOISTURE EQUIVALENT L 0 L 2 .5 L 5.0 L 7.5 Miami s a n d y l o a m 13 *98 13.76 1I+.16 li|.o21 B r o o k s t o n c l a y lo a m 21 . 5 1 . 2 2 . 0i|. 22.18 22.59 "L ignin" TABLE 5 PERCENT MOISTURE OF SOILS TREATED WITH DIFFERENT RATES OF "LIGNIN" AT HYGROSCOPIC COEFFICIENT L 0 L 2.5 L 5.0 L 7. 5 Miami s a n d y lo a m 0 .I4.6 0.53 0,52 0 .5 3 B r o o k s t o n c l a y lo a m 1.33 1.14-05 1.60 1 .7 2 "L ignin" 4.29 20 I n stu d y in g s o i l m o istu re , one i s o f te n concerned w i t h t h e am ount o f w a t e r a v a i l a b l e t o p l a n t s w h i c h may o r may n o t b e i n c r e a s e d b y t h e a d d i t i o n o f o r g a n i c m a t t e r , c l e a r l y shown b y F e u s t e l an d B y e r s ( 2 0 ) « as For p ra c tic a l p u r p o s e s , t h e t e r m ’’a v a i l a b l e w a t e r ” c o u l d b e i n t e r p r e t e d a s t h e amount o f w a t e r h e l d a t f i e l d c a p a c i t y m in u s t h e amount o f w a t e r h e l d a t h y g r o s c o p i c c o e f f i c i e n t , or for l o a m s , t h e am ount o f w a t e r h e l d a t m o i s t u r e e q u i v a l e n t m in u s t h e amount o f w a t e r h e l d a t h y g r o s c o p i c c o e f f i c i e n t sin ce i t has been found (2, 5 2 ) t h a t th e f i e l d c a p a c ity f o r l o a m s was a b o u t t h e same a s m o i s t u r e e q u i v a l e n t . The a v a ila b le w a te r of th e d i f f e r e n t l y t r e a t e d s o i l s i s thus compared i n F ig u r e I I I . Note t h e s l i g h t i n c r e a s e i n a v a i l a b l e w a te r f o r t r e a t e d s o i l s o v e r t h a t o f check s o i l , an d t h e t r e m e n d o u s am ou nt o f a v a i l a b l e w a t e r h e l d b y ’’l i g n i n ” . (J4.) R h e o l o g i c a l p r o p e r t i e s A l l t h e p l a s t i c i t y s t u d i e s i n t h i s i n v e s t i g a t i o n were determ ined by A t t e r b e r g ’ s p ro ced u re (6 ). Shown i n T a b l e 6 a r e p e r c e n t m o i s t u r e a t u p p e r an d l o w e r p l a s t i c l i m i t s , s t i c k y p o i n t and p l a s t i c i t y num ber. As i n d i c a t e d i n T a b l e 6 , t h e a d d i t i o n o f ’’l i g n i n ” i n c r e a s e s t h e p e r c e n t m o i s t u r e a t u p p e r an d l o w e r p l a s t i c lim its a n d s t i c k y p o i n t d e s p i t e t h e f a c t t h a t ’’l i g n i n ” itself d o e s n o t d i s p l a y any p l a s t i c i t y . I t h a s been d e m o n s tr a te d t h a t i n o r d e r f o r a s o i l to become p l a s t i c , s u f f i c i e n t w a t e r m ust be added to p ro v id e 21 TABLE 6 PERCENT MOISTURE OP SOILS TREATED WITH DIFFERENT RATES OF "LIGNIN" AT UPPER AND LOWER PLASTIC LIMITS, STICKY POINT AND PLASTICITY NUMBER Upper p l a s t i c l i m i t Miami s a n d y l o a m B ro o k s to n c l a y loam Lower p l a s t i c l i m i t Miami s a n d y lo a m B ro o k s to n c l a y loam S ticky p o in t Miami s a n d y l o a m B ro o k s to n c l a y loam P l a s t i c i t y num ber M iam i s a n d y lo a m B r o o k s to n c l a y loam L 0 L 2.5 L 5o0 l 2^.32 25.27 2 5 ,1 8 2 6 .0 8 38.72 40.67 4 2 .7 5 4 0 .7 1 17.28 17.52 1 8 ,3 8 18,144 2i|.* 02 24.94 2 5 .3 5 2 4 .7 1 17.37 17.36 1 8 .0 0 1 8 .4 9 24,06 24.90 2 5 .9 0 25.45 7.05 7.75 6 ,8 0 7.64 14.70 16.73 1 7 .4 0 1 6 .0 0 7.5 22 a film around each p a r t i c l e . The o r i e n t a t i o n o f p a r t i c l e s a n d t h e i r s u b s e q u e n t s l i d i n g o v e r one a n o t h e r t h e n t a k e s place. Such o r i e n t a t i o n betw een th e co llo id al i n c r e a s e s t h e am ount o f c o n t a c t surfaces. This g r e a t e r c o n t a c t , t o g e t h e r w i t h an i n c r e a s e i n t h e p r o p o r t i o n o f w a t e r - f i l m s u r f a c e t o t h e p a r t i c l e m a s s , may b e c o n s i d e r e d a s p r o d u c i n g the p l a s t ic effect. Iso lated lig n in -lik e tiv e capacity fo r w ater. organic m atter has a h ig h absorp­ It t a k e s up t h e f i r s t w a t e r added w h ich would h av e b e e n a v a i l a b l e f o r o r i e n t a t i o n o f so il p a r tic le s . H y d r a t i o n o f l i g n i n m ust be f a i r l y com plete b e f o r e s u f f i c i e n t w a t e r becomes a v a i l a b l e f o r f i l m f o r m a t i o n around m in e ra l p a r t i c l e s . C onsequently, the p l a s t i c i t y l i m i t s and s t i c k y p o i n t s o c c u r a t r e l a t i v e l y h ig h m o is tu re content. T h i s m e a n s t h a t t h e l i g n i n - t r e a t e d s o i l w o u l d be l e s 3 e a s ily puddled. I t means a l s o t h a t s o i l w o rk in g t o o l s w o u l d b e l e s s l i k e l y t o " s c o u r " i n s o i l w h e r e l i g n i n was a dded o R ussel is ( 5 0 ) h a s r e p o r t e d t h a t t h e p l a s t i c i t y nu m b er a l in e a r fu n c tio n of th e clay content (5 u p a r t i c l e s ) . The p l a s t i c i t y n u m b e r a s shown i n T a b l e 6 c h a n g e s w i t h ''l i g n i n ” a d d i t i o n alth o u g h th e c la y c o n te n t rem ains r e l a ­ tiv e ly co n stan t. B av e r (11) p o i n t e d o ut t h a t th e p l a s t i c ­ - P2 N where pl p2 } F-^ a n d F£ a r e t h e f i l m t e n s i o n s a t u p p e r a n d low er i t y number was p r o p o r t i o n a l t o t h e r a t i o p lastic lim its. ( pl He c l a i m e d t h a t t h e n a t u r e o f c o l l o i d a l m a t e r i a l m ig h t change th e p r o p o r t i o n a l i t y c o n s t a n t . Since 23 lig n in is d i f f e r e n t i n n a t u r e from c o l l o i d a l possible fo r i t to a f f e c t t h i s clay, it is constant# (5 ) P o r o s i t y The m e t h o d o f L e a r n e r a n d Shaw ( 3 1 ) was u s e d f o r t h e d e te rm in a tio n o f p o r o s ity w ith th e m o d ific a tio n th a t the s o i l p a s s i n g t h r o u g h a two m i l l i m e t e r s i e v e w as u s e d i n s t e a d o f an u n d i s t u r b e d sam ple. The m o d i f i c a t i o n was n e c e s s a r y b e c a u s e o f a l i m i t e d amount o f s o i l . A pproxi­ m a te ly e q u a l amounts o f s o i l w ere p l a c e d i n t h e b r a s s c y l i n d e r s a n d d e t e r m i n a t i o n s w e r e made f o r t o t a l p o r o s i t y , c a p i l l a r y p o r o s i t y a n d p o r o s i t y a t 1 0 , 2 0 , 30, ip0, cm w a t e r t e n s i o n s . a n d 60 The d a t a a r e t a b u l a t e d i n T a b l e s 7 a n d 8» I n o rd e r to have a b e t t e r e v a lu a tio n of th e d a ta p r e s e n t e d i n T a b l e s 7 a-n(3. 8 , p e r c e n t p o r o s i t y a t v a r i o u s s o i l m o is tu r e t e n s i o n s as a f f e c t e d by " l i g n i n ” tr e a tm e n ts is shown g r a p h i c a l l y i n F i g u r e IV# It c a n b e n o t e d f r o m F i g u r e IV t h a t ” l i g n i n ” a l o n e showed v e r y lo w p o r o s i t y b u t when i t w a s a d d e d t o s o i l and a l l o w e d t o s t a n d f o r f i v e weeks d u r in g w hich w a te r was a d d e d p e r i o d i c a l l y a s d e s c r i b e d u n d e r p r o c e d u r e f o r lab o rato ry stu d ies, various te n s io n s 7 and 8 ) . it increased percent p o ro sity at and d e c r e a s e d t h e c a p i l l a r y p o r o s i t y (Tables T h is r e l a t i o n can be e x p l a i n e d by t h e f a c t t h a t " lig n in ” alone, due t o its low f o r c e o f c o h e s io n , does n o t form s t a b l e a g g r e g a t e s and i t h o l d s w a t e r a g a i n s t v a r i o u s 21+ TABLE 7 PERCENT POROSTTY OF MIAMI SANDY LOAM SOIL TREATED WITH DIFFERENT RATES OF "LIGNIN" AT VARIOUS TENSIONS T otal p o r o s ity P orosity at 1 0 cm H20 20 30 i+o 60 C apillary p o ro sity L 0 L 2.5 L 5.0 L 7.5 51+.71+ 51+. 95 51+.85 55.67 6.98 10.92 12.51 13.25 7.07 11.58 13.28 ’7 . 7 1 1 2 . 72. li+.i+i 15.81+ 1+0.51+ 15.1+3 17.13 39.1+2 8.03 13.65 15.35 16.65 18.39 39.02 114-85 i+1 oi+8 11+.27 • TABLE 8 PERCENT POROSITY OF BROOKSTON CLAY LOAM SOIL TREATED WITH DIFFERENT RATES OF "LIGNIN" AT VARIOUS TENSIONS "L ignin" L 0 L 2.5 L 5.0 L 7.5 T otal p o ro sity 6 3 .8 3 66.1+7 66.65 65.1+2 65.20 P oro sity at 10 cm H2 O 20 11.51+ 1 8 .3 2 12.79 20.20 13.93 19.92 12.76 21.65 23.82 23.99 26.50 29.70 23.27 27.72 3.33 3.33 5.71 39.97 38.93 30 1+0 60 C ap illary p o ro sity 27.15 1+0.01 28.05 20.51+ 23.60 25.83 28.1+5 39.61 7.63 13.81 57«57 P . i g u r e I V ... P e r c e n t . . p o r o e i t y f so ils t r e a t e d v / i t h ' d i f f e r e n t i r a t e s o f it'liiei a t various ten sio n s jr:: B rookston c l a y lo a m 24 P o r o Ti Miam i:. s aridy.:. lo a m in 1 to 25 te n sio n s w ith g r e a te r fo rce because of i t s high w ater h o ld in g c a p a c i t y w hich r e d u c e s p e r c e n t p o r o s i t y c o n s i d e r ­ ably. When i t was a d d e d t o s o i l on t h e o t h e r h a n d , re s u lte d in in c re a se d ag g reg atio n because of i t s it strong a d h e s i v e f o r c e a s i l l u s t r a t e d i n T a b le s 2 and 3 . The r e l a t i o n s h i p b e tw e e n s i z e o f a g g r e g a t e s and p e r c e n t p o r o s i t y h a s b e e n d e m o n stra te d by D oiarenko (30). found t h a t as th e s i z e o f a g g re g a te in c r e a s e d , He the to ta l p o r o s i t y an d n o n - c a p i l l a r y p o r o s i t y i n c r e a s e d w h i l e t h e c a p illa ry p o ro sity decreased. It should be p o i n t e d out t h a t t o t a l p o r o s i t y i s n o t as i m p o r t a n t f o r c h a r a c t e r i z i n g t h e s t r u c t u r a l p r o p e r t i e s of s o i l s . a s i s the r e l a t i v e d i s t r i b u t i o n of the pore s iz e s . That i s th e r e l a t i v e p r o p o rtio n o f c a p i l l a r y to non-cap­ i l l a r y p o r e s i s a b e t t e r m easure o f s o i l s t r u c t u r e th a n i s to tal space (11). The n a r r o w e r t h e p r o p o r t i o n o f c a p i l l a r y to n o n - c a p illa r y pore spaces, the s o i l . th e b e t t e r the s tr u c tu r e of A v a l u e o f u n i t y i s c o n s i d e r e d t o be i d e a l , since a t t h i s v a lu e , equally divided. t h e l a r g e and s m a ll p o r e s a r e a b o u t The a d d i t i o n o f " l i g n i n " to s o i l tends t o n a rro w t h i s p r o p o r t i o n and t h e r e f o r e im p ro v es th e s tr u c tu r e of the s o il (T a b le s 7 and 8 ) . B. C h e m i c a l (1 ) E x c h a n g e c a p a c i t y d e t e r m i n a t i o n s w e r e made a c c o r d i n g to t h e m ethods p r e s c r i b e d by P eech, Dean, a n d R ee d ( ^ 6)0 T w e n t y - f i v e g r am s o f a i r d r y s o i l was s h a k e n w i t h 2%0 ml n e u t r a l N ammonium a c e t a t e s o l u t i o n , allow ed to stand 26 f o r 20 m i n u t e s , and f i l t e r e d . E x c e s s ammonium a c e t a t e was w a s h e d o u t f r o m t h e a m m o n i u m - s a t u r a t e d s o i l w i t h 2j?0 ml 9^ p e r c e n t e t h y l a l c o h o l, u s in g sm all p o r t i o n s a t a tim e and d r a i n in g w e l l each tim e* T h e n t h e s o i l was l e a c h e d w i t h 200 ml 10 p e r c e n t NaCl s o l u t i o n t o e x t r a c t a d s o r b e d ammonium f r o m the s o i l . The NaCl e x t r a c t w as t r a n s f e r r e d t o a K j e l d a h l f l a s k , t o w h i c h NaOH was a d d e d t o make an a p p r o x i m a t e l y N s o l u t i o n , an d d i s t i l l e d i n t o 5>0 ml o f If. p e r c e n t b o r i c a c i d . d i s t i l l a t e w as t i t r a t e d w i t h The s t a n d a r d 0 . 1 N HC1, u s i n g b ro m c reso l g re e n as i n d i c a t o r . The e x c h a n g e c a p a c i t i e s o f . t h e s o i l s t h u s d e t e r m i n e d a r e shown i n T a b l e 9o The r e s u l t s o f t h e a n a l y s e s o f t h e b a s e e x c h a n g e cap acities, g i v e n i n T a b l e 9# t e n d t o " l i g n i n ” when a d d e d t o s o i l cap acity . dem onstrate t h a t s l i g h t l y i n c r e a s e s th e exchange D i f f e r e n t view s have been e x p re s s e d by v a r io u s a u th o r s as t o th e cau se o f t h i s i n c r e a s e , B a r t l e t t and Norman (9) b e l i e v e d t h a t t h e i n c r e a s e i n b a s e e x c h a n g e c a p a c i t y was due t o an i n c r e a s e i n a c t i v i t y o f t h e l i g n i n . M i l l a r and h i s co-w orkers (37) a g r e e d w i t h th e m i n t h a t th e y found a change i n th e a d s o r p t i v e c a p a c i t y o f l i g n i n o c c u r r e d on d e c o m p o s i t i o n . o th e r hand, Waksman a n d I y e r (68), on t h e a t t r i b u t e d th e in c r e a s e i n exchange c a p a c ity t o t h e f o r m a t i o n o f a l i g n o - p r o t e i n c o m p l e x w h i c h h a s an exchange c a p a c i t y c o n s id e r a b l y h i g h e r th a n t h a t o f l i g n i n or p r o te in alone. I t i s n o t p o s s ib le to t e l l from th e r TABLE 9 EXCHANGE CAPACITIES OP SOILS TREATED WITH DIFFERENT RATES OF "LIGNIN" ______ M il l i e q u i v a l e n t s p er 100 gram3____________ Miami sandy B rook ston '’L ign in " lo a n c la y loam L 0 7d7 1 8 .1 8 L 2*5 7.i+3 18.37 L 5*o 7 J-i-2 18.39 7 .5 7.59 18.61 l 19.00 28 data re p o rte d in t h i s used to e x p l a i n t h i s s tu d y w hich h y p o th e s is sh o u ld be increase. The g r o u p i n g s a c t i v e i n r e t e n t i o n o f c a t i o n s a r e l i k e l y t o b e p h e n o l i c h y d r o x y l g r o u p s an d p o s s i b l y c a r ­ boxyl g ro u p s, though i t i s d o u b tfu l w hether th e l a t t e r are p r e s e n t in norm al l i g n i n It i s b e l i e v e d t h a t i f a l a r g e r amount o f " l i g n i n ” were u s e d , t h e d e g re e o f i n c r e a s e i n exchange c a p a c i t y would a l s o be i n c r e a s e d . le v e l of "lig n in " b asis) (9). In th is experim ent, the h ig h e s t a p p l i c a t i o n was 0 .7 5 p e r c e n t ( o n a s o i l o f w h i c h o n l y ij.2 .5 3 p e r c e n t was r e p o r t e d t o b e actu al lig n in (s e e T able 1 ) . The e x c h a n g e c a p a c i t y o f t h e " l i g n i n " u s e d i n t h i s s t u d y w as f o u n d t o b e 19 m i l l i e q u i v a l e n t s p e r 100 gr am s of the m a te r ia l. This i s i n c lo s e agreem ent w ith th e v alu e o f 17»9 r e p o r t e d b y Waksman a n d I y e r ( 6 8 ) . (2 ) pH m e a s u r e m e n t To 25 g r am s o f a i r d r y s o i l was a d d e d 1 0 0 ml o f d i s ­ t i l l e d w ater. A fter s ti r r i n g f o r one m i n u t e t h e pH o f t h e s a m p l e w as d e t e r m i n e d w i t h a Beckman pH m e t e r . The r e s u l t s are r e p o r t e d i n T able 10, D e s p i t e t h e l o w pH o f t h e " l i g n i n " m a t e r i a l u s e d , its a d d i t i o n t o s o i l t e n d e d t o i n c r e a s e t h e pH v a l u e o f the s o il th is slig h tly (s e e Table 1 0 ) . same t y p e o f i n c r e a s e . A ries (If.) a l s o f o u n d The i n c r e a s e i n pH o f t h e s o i l due t o t h e a d d i t i o n o f " l i g n i n " c a n p o s s i b l y b e a t t r i b u t e d t o e i t h e r o n e o r b o t h o f t h e f o l l o w i n g two f a c t o r s : F irst, TABLE 1 0 pH OP SOILS TREATED WITH DIFFERENT RA.TES OF "LrGNIN" Miami s a n d y lo a m B rookston c l a y lo a m "Lignin" L 0 6.52 6.52 1.99 L 2.5 .6 »8l 6.89 L 5.0 6.88 6.56 L 7 o5 6 .9 0 6,58 30 the in c re a se d a d so rp tiv e c a p a c i t y o f t h e t r e a t e d s o i l which may r e t a i n m o re b a s e s t h a n t h e u n t r e a t e d s o i l , the p o s s ib le and second, ch an g es w h ic h l i g n i n u n d e r g o e s on d e c o m p o s itio n * B ertram so n and W hite (13) p o i n t e d o u t t h a t t h e r e a r e a t l e a s t two c h a n g e s known t o o c c u r d u r i n g d e c o m p o s i t i o n o f l i g n i n w h i c h e x p o s e OH g r o u p s o f t h e l i g n i n m o l e c u l e . T h e se changes a r e p a r t i a l d e m e t h y l a ti o n and d e p o ly m e r iz a tio n b o t h o f w h i c h w i l l c a u s e a n i n c r e a s e i n pH v a l u e . (3 ) N i t r a t e d e t e r m i n a t i o n s w e r e made a c c o r d i n g t o t h e method s u g g e s te d by P r i n c e (49)• F i f t y g r a m s a i r d r y s o i l w e r e p l a c e d i n a 500 ml flask , t o w h i c h was a d d e d 1 ,5 g r a m s o f p u l v e r i z e d q u i c k ­ l i m e (CaO) a n d 20 0 ml d i s t i l l e d w a t e r . m inutes, allow ed to Shaken f o r 3 -5 s t a n d f o r 20 m i n u t e s a n d f i l t e r e d . F i f t y ml o f t h e f i l t r a t e w a s p l a c e d i n a 10 0 ml b e a k e r an d e v a p o r a t e d j u s t t o d r y n e s s o n warm p l a t e . When c o o l , t h e r e s i d u e s were m o i s t e n e d q u i c k l y and t h o r o u g h l y w i t h two ml p h e n o l d i s u l f o n i c a c i d . rubbed w ith a f l a t The s i d e s o f d i s h w e r e s t i r r i n g r o d and a llo w ed t o s ta n d f o r 10 m i n u t e s . A f t e r d i l u t e d w i t h 20 ml w a t e r , e x c e s s ammonium h y d r ­ o x i d e w as a d d e d u n t i l y e l l o w c o l o r was f u l l y d e v e l o p e d . The s o l u t i o n was made up t o 50 ml w i t h w a t e r a n d t h e n itrate c o n t e n t was d e t e r m i n e d c o l o r i m e t r i c a l l y , blue f i l t e r . using a 31 (i|.) P h o s p h a t e d e t e r m i n a t i o n s w e r e made a c c o r d i n g t o methods s u g g e s t e d by B ra y and K u r t z (l5)» ’’A c i d s o l u b l e a n d a d s o r b e d ” p h o s p h a t e ? S e v e n ml o f 0«1 N H C 1 - 0 . 0 3 N NH^F s o l u t i o n a n d one gram o f a i r d r y s o i l w a s p l a c e d i n t o a flask , shaken f o r one m i n u t e a n d f i l t e r e d . To s i x ml o f t h e f i l t r a t e w e r e a d d e d f i v e d r o p s o f NH[j_Mo-HCl s o l u t i o n a n d f i v e d r o p s F - S r e a g e n t . The t r a n s ­ m i s s i o n w as r e a d on L u m e t r o n c o l o r i m e t e r i n 5 - 6 m i n u t e s , using re d f i l t e r (650 m u ). ’’A d s o r b e d ” p h o s p h a t e : Same a s a b o v e e x c e p t t h e e x t r a c t i n g r e a g e n t was 0 . 0 2 5 N HC I-O .O 3 N NH^F. (5) Ca, Mg d e t e r m i n a t i o n s w e r e made a c c o r d i n g t o m e t h o d s s u g g e s t e d b y Cheng a n d B r a y ( 1 7 ) • Ca: F i v e g r a m s a i r d r y s o i l w e r e s h a k e n w i t h 10 ml 23 p e r ­ c e n t NaNO^ f o r o n e m i n u t e a n d f i l t e r e d . F i v e ml o f t h e f i l t r a t e w e r e d i l u t e d t o 50 ml w i t h w a t e r , t o w h ic h were a d d e d two ml 1 0 p e r c e n t KOH s o l u t i o n a n d 0 . 3 gram o f i n d i ­ c a t o r powder. The s o l u t i o n w a s s t i r r e d a n d t i t r a t e d w i t h 0 . 4. p e r c e n t v e r s e n a t e s o l u t i o n t o e n d p o i n t . was c o m p a r e d w i t h s t a n d a r d s . The c o l o r The s o l u t i o n s w e r e s a v e d f o r Mg d e t e r m i n a t i o n s . Mg: F i v e ml KH^_C1-NH^0H b u f f e r , one ml 2 p e r c e n t KCN 32 s o l u t i o n a n d s i x d r o p s F -2l|2 i n d i c a t o r w e r e a d d e d , s o l u t i o n was s t i r r e d The a n d t i t r a t e d w i t h O.ij. p e r c e n t v e r s e n - a t e s o l u t i o n t o end p o i n t # N o t e — o n e ml o f O.I 4. p e r c e n t v e r s e n a t e s o l u t i o n i s e q u i v a l e n t t o 0#i^35 mgm Ca o r 0 . 1 9 8 mgm Mg# (6 ) D e t e r m i n a t i o n o f e x c h a n g e a b l e Na an d K i n s o i l To f i v e g r a m s o f s o i l was a d d e d 0 . 5 gram ammonium o x a l a t e c r y s t a l an d 50 ml o f e x t r a c t i n g s o l u t i o n a n d O.OI4. N ammonium o x a l a t e ) . (2 N NH^Ac The s o l u t i o n w as s h a k e n , a llo w e d t o s t a n d o v e r n i g h t and f i l t e r e d . The f l a s k w a s r in s e d th re e tim es w ith the e x tr a c tin g s o lu tio n . Made up t o 1 0 0 ml a n d t h e c o n c e n t r a t i o n s o f Na an d K w e r e d e t e r ­ m ined w i t h fla m e p h o to p ie te r. The r e s u l t s o f c h e m i c a l a n a L y s e s a r e shown i n T a b l e 11# A lthough A rie s (ij.) r e p o r t e d an i n c r e a s e i n s o l u b l e P a n d Ca o f s u l f i t e l i g n i n - t r e a t e d s o i l , in t h i s experim ent. r e s u l t s o f P, in co n sisten t. i t was n o t o b s e r v e d As c a n b e s e e n f r o m T a b l e 1 1 , t h e Ca, Mg, a n d Na d e t e r m i n a t i o n s w e r e r a t h e r " L ig n in " d id , however, cause an i n c r e a s e in th e exchangeable p o tassiu m c o n te n t o f s o i l . It is i n t e r e s t i n g to note t h a t " l i g n i n " - t r e a t e d s o il contained a h i g h e r t o t a l c o n t e n t o f e x c h a n g e a b l e Ca, Mg, Na a n d K than d id th e u n tre a te d s o i l . as t h e r a t e o f " l i g n i n " It sh o u ld a l s o be n o te d t h a t a p p l i c a t i o n i n c r e a s e d t h e r e was a corresponding decrease in th e n i t r a t e co ntent of th e s o il (F ig u r e V). T h is change can be a t t r i b u t e d to t h e i n c r e a s e d TABLE 1 1 TOTAL AND ADSORBED P (PPM), EXCHANGEABLE Ca, Mg, Na, K, AND'NO. (MGMS PER 10 0 GRAMS OP SOIL) OP SOILS TREATED WITH DIFFERENT RATES OF^'LIGNIN" Miami s a n d y lo a m L 0 B r o o k s to n c l a y loam L 2.5 L 5.0 L 7 .5 '' L ig n . in " L 0 L 2.5 L 5»o L 7 .5 31.53 30.90 3 O0I4.2 3 0 .6 6 1 .2 I4.26 4.50 14.09 1 .2 97.80 99.00 87.80 11.52 12.81]. T otal P 7o09 7.05 5.52 5 ci^6 Ad. P 3 .6 0 2.99 3 .0 0 3 .1 2 Ca 39.60 39.20 3 6 ,6 0 37.60 Mg 3.02 ^-•72 1 .9 9 3.20 9 J 4I4 17.76- Na I4.80 14-.92 14-72 7.20 3.1^2 3.38 3.9k 14.142 7.00 K 3.0i| 2.92 3.72 3.32 12.90 1-14-514- 114.56 1 6 .6 6 0.50 NO3 3.29 2.72 1.92 1 .7 6 I48.0 8 38.61]. 38.56 26.90 14.56 91.20 25.80 0 treated r a t e cdnt rit o f : s o i l s : : I d i f f rent r a t e s o f i’- l i g n i n 3.0 US !-_o 25 LO loam Lx S B rookston loam ■Figure I X . Ca r b o n d i o x Lde p r o d u c t i o n •t r e a t ' e ' d ; wi:t'H"'diTf prerit"' r a t e ' 3 of'-' ’TIg'n an Lio t 2 .g: t- 5 .o Mi am i s anc . y : l o Lie Brool Li.S cl. l o am 3k m icrobial a c tiv ity ( s e e T a b l e 12) w h i c h i m m o b i l i z e d , t h e so il av ailab le n itr a te . (7) B u f f e r c u rv e T w e n t y - f i v e g r a m s o f a i r d r y s o i l a n d 100 ml 0 . 1 N HC1 w e r e p l a c e d i n t o a 2 $ 0 ml E r l e n m e y e r f l a s k , a l l o w e d t o s t a n d o v e r n i g h t an d f i l t e r e d . shaken, I t was l e a c h e d w i t h a d d i t i o n a l 200 ml 0 . 1 N HC1 a n d w a s h e d w i t h 250 ml 95 p e r c e n t a l c o h o l a n d t h e n w i t h 300 m l o f d i s t i l l e d w a t e r , adding a sm all p o r tio n a t a tim e . The s o i l was t r a n s f e r r e d t o 250 ml b e a k e r a n d a l l o w e d t o a i r d r y . o f w a t e r were added and t h e NaOH p o t e n t i o m e t r i c a l l y . w ith w a te r. T w e n t y - f i v O ml s o i l was t i t r a t e d w i t h 0 . 1 N The ’’l i g n i n " was w a s h e d o n l y A fte r a i r d rying, 25 ml w a t e r a n d B a C l 2 i n e x c e s s w e r e a d d e d a n d t h e n t i t r a t e d w i t h 0 . 1 0 6 N NaOH p o ten tio m etrically . V II, The r e s u l t s a r e shown i n F i g u r e s V I , and V I I I . It appears t h a t the b u f f e r c a p a c ity of both s o il s w as s l i g h t l y i n c r e a s e d a s a r e s u l t o f " l i g n i n " The g r e a t e s t b u f f e r a c t i o n o f " l i g n i n " 6 ,5 and 8 .0 ad d itio n . l i e s b e t w e e n pH (see F igure V I II ). A c o m p a r i s o n b e t w e e n t h e pH o f t h e H - s a t u r a t e d " l i g n i n " and t h a t o f o r i g i n a l " l i g n i n " r e v e a l s t h a t t h e r e was an i n c r e a s e o f 0 . 7 1 i n t h e pH v a l u e o f t h e f o r m e r . This d i f f e r e n c e l e a d s one t o s u s p e c t t h a t some c h a n g e h a d t a k e n p la c e d u rin g th e hydrogen s a t u r a t i o n p ro c e s s . o f t h e c h a n g e i s unknown* . The n a t u r e Figure V I I. Buffer c u r v e s : of:: Brooks-;on>c la y loam tr e ated ; wi d i f f e r e n t r a t e s of "ligninw : o_ w 35 C. B i o l o g i c a l One m e t h o d f o r m e a s u r i n g c h a n g e s i n t h e m e t a b o l i c a c t i v i t i e s of s o i l m icroorganism s i s d ioxide p ro d u c tio n i n the s o i l . to m easure carbon The c a r b o n d i o x i d e p r o - - d u c t i o n i n t h i s e x p e r i m e n t was d e t e r m i n e d a c c o r d i n g t o Waksmanf s m e t h o d ( 6 2 ) , One h u n d r e d g r a m s o f a i r d*ry s o i l was p l a c e d i n a 1 2 5 ml E r l e n m e y e r f l a s k . S u ffic ie n t w ater was a d d e d t o b r i n g t h e s o i l t o m o i s t u r e e q u i v a l e n t a c c o r d ­ i n g t o t h e d a t a r e c o r d e d i n T a b l e ip* The a p p a r a t u s u s e d i n t h i s e x p e r i m e n t i s d i a g r a m m e d i n F i g u r e X. A i r was p a s s e d s u c c e s s i v e l y t h r o u g h a s t r o n g NaOH s o l u t i o n , a n d t h r o u g h a s t a n d a r d KOH s o l u t i o n . over the s o il, A i r f l o w w as r e g u ­ l a t e d t o a p p r o x i m a t e l y 20 b u b b l e s p e r m i n u t e a n d a l l o w e d to flow f o r a p e r i o d o f f i v e m in u te s . T h i s p r o c e s s was r e p e a t e d a f t e r a p e r i o d o f two d a y s a n d a g a i n b e f o r e titratio n two d a y s l a t e r . The KOH s o l u t i o n w as t i t r a t e d w i t h s t a n d a r d HC1 a n d t h e w e i g h t o f c a r b o n d i o x i d e e v o l v e d from t h e s o i l c a l c u l a t e d . The d a t a o b t a i n e d i n t h i s e x p e r i m e n t a r e sh own i n T a b l e 1 2 • The r e s u l t s o f t h i s itio n of "lignin" activ ity . to the experim ent i n d i c a t e t h a t th e add­ s o il stim u lated the m icrob ial The i n c r e a s e i n c a r b o n d i o x i d e , as i l l u s t r a t e d i n F ig u re IX, i n d i c a t e d t h a t d eco m p o sitio n of th e " l i g n i n " m a t e r i a l w as t a k i n g p l a c e . i n T able 1, As shown by t h e d a t a r e p o r t e d the " l i g n i n ” m a te ria l used i n t h i s stu d y con­ t a i n s 5 6 . 3 p e r c e n t c e l l u l o s e a n d 1+2• 53 p e r c e n t l i g n i n . This evolution soil So ion of carbon dioxide and. without " l i g treatm ent TABLE 1 2 CARBON DIOXIDE PRODUCTION OF SOILS TREATED WITH DIFFERENT RATES -OF "LIGNIN” ____________ M i l l i g r a m s p e r 10 0 gra m s s o i l ___________ Miami s a n d y B rookston "Lignin" loam c l a y lo a m 0 6 .7 0 6 8 12.075 2 .5 7 .2 8 1 8 1 3 .1 1 0 5.o 7.^570 15.699 7 .5 8 .2 8 0 0 1 6 .1 6 0 l 8 .l4.OO . ' 37 c o m p lic a te s th e problem o f d e te r m in in g w h e th e r t h e l i g n i n o r t h e c e l l u l o s e w a s b e i n g a t t a c k e d by t h e .ismso s o il m icrorgan- Many w o r k e r s h a v e shown t h a t i s o l a t e d l i g n i n was q u ite r e s is ta n t to m icrobial a tta c k . O thers (63) in d ic a te d t h a t l i g n i n w as n o t a b s o l u t e l y r e s i s t a n t t o d e c o m p o s i t i o n b u t c o u l d be g r a d u a l l y o x i d i z e d by c e r t a i n f u n g i . la tter, however, ta k e s a r e l a t i v e l y lo n g tim e whereas th e " l i g n i n " and s o i l i n t h i s f iv e weeks. in th is It The e x p e r i m e n t were i n c u b a t e d o n l y i s b e lie v e d th a t the p e rio d of in c u b a tio n e x p e r i m e n t was n o t l o n g e n o u g h t o b r i n g a b o u t a n y co n sid e rab le tra n sfo rm a tio n of the "lig n in " m a te ria l. is, th erefo re, It c o n c lu d e d t h a t most o f th e i n c r e a s e d ca rb o n d i o x i d e p r o d u c t i o n w h i c h r e s u l t e d fro m t h e a p p l i e d " l i g n i n " was d u e t o t h e d e c o m p o s i t i o n o f t h e c e l l u l o s e c o n t a i n e d i n the " lig n in " m aterial* IV . GREENHOUSE STUDIES Procedure: Two s p l i t p l o t e x p e r i m e n t s w e r e d e s i g n e d t o effect study th e o f '’l i g n i n 1’ u s e d a s a m u l c h an d m i x e d w i t h s o i l the y i e l d of tom atoes (S to k esd ale) on and s p r i n g w h e a t( H e n ry ), w i t h a n d w i t h o u t f e r t i l i z e r a n d l i m e on Miami s a n d y l o a m so il. The p l a n t s w e r e g row n i n t w o - g a l l o n j a r s e x p e r i m e n t w as r e p l i c a t e d f o u r t i m e s . and each The t r e a t m e n t s u s e d i n t h e s e e x p e rim e n ts a r e o u t l i n e d below : 1 . ’’L i g n i n Rate o f a p p l i c a t i o n 0 2*5 5.0 7 .5 tons p e r acre L 0 tons p e r a c r e L 2* 5 tons p e racre L 5.0 tons p eracre L 7 .5 2. F e r t i l i z e r I4. - I 6 - 8 f o r t o m a t o e s ; 3 - 1 2 - 1 2 f o r s p r i n g w h e a t Rate o f a p p l i c a t i o n • 0 lb s/acre F 0 1000 l b s / a c r e F 1 3 . Lime Rate o f a p p l i c a t i o n "L ig n in '', 0 lb s/acre 1000 l b s / a c r e f e r t i l i z e r and lim e w ere mixed w i t h th e s o i l j u s t b e f o r e t r a n s p l a n t i n g o f th e tom ato p l a n t s o r s e e d in g of s p rin g w heat. " L i g n i n " was a p p l i e d a s a m u l c h when t h e p l a n t s h a d r e c o v e r e d fro m t r a n s p l a n t i n g o r a f t e r t h i n n i n g in case of w heat. W a t e r i n g w as d o n e w i t h d i s t i l l e d w a t e r , . 39 Ao E x p e r i m e n t w it h . T o m a t o e s o n Miami S a n d y Loam The e f f e c t o f '’l i g n i n " on tom ato y i e l d s i s shown i n T able 13. It c a n be n o t e d from t h e d a t a t h a t t h e a v e r a g e y i e l d s o f tom atoes i n " l i g n i n " - t r e a t e d s o i l s exceeded s i g n i f i c a n t l y t h o s e from u n t r e a t e d s o i l s . to the " lig n in " relatio n sh ip catio n . T he i n c r e a s e was i n p r o p o r t i o n t r e a t m e n t up t o t h e f i v e t o n r a t e , d id n o t h o ld f o r th e 7e5 to n " l i g n i n " The ap p li­ T h is c o i n c i d e s w i t h t h e r e s u l t s r e p o r t e d by A r i e s ( I).) a n d U. S . F o r e s t P r o d u c t L a b o r a t o r y ( 2 6 ) . A b r e a k d o w n o f T a b l e 13 g i v e s i n t e r e s t i n g r e s u l t s w h i c h a r e t a b u l a t e d i n T a b l e lip. It is a p p a re n t t h a t m ulching, f e r t i l i z e r application and l im i n g i n c r e a s e d t h e e f f e c t i v e n e s s o f " l i g n i n " , N o te th e d e p r e s s iv e e f f e c t o f m ixing a t h ig h l e v e l o f " l i g n i n " a p p l i c a t i o n w h e r e no f e r t i l i z e r a n d l i m e w e r e u s e d . This s u g g e s ts t h a t th e drop i n y i e l d beyond f i v e to n s p e r a c re was due p r o b a b l y t o t h e l a c k o f n i t r o g e n s u p p l y . B. E x p e r i m e n t w i t h W h e a t on Miami S a n d y Loam T w e n t y w h e a t s e e d s w e r e sown i n e a c h p o t . se e d lin g s reach ed 1 -1 .5 in ch es high, to s ix p la n ts p e r p o t. h e a d s were h a r v e s te d , recorded. A fte r the t h e y w e r e t h i n n e d down A f t e r th e p l a n t s were m a tu re , the t h r e s h e d and th e w e ig h t o f g r a i n s The y i e l d o f s p r i n g w h e a t g r a i n s a s a f f e c t e d by d iffe re n t ra te s of "lig n in " ap p licatio n is shown i n T a b l e l 5 o 40 TABLE 13 EFFECT OF "LIGNIN" ON THE YIELD OF TOMATO PLANTS GROWN ON A MIAMI SANDY LOAM SOIL Grams p e r p o t L 0 L 2 .5 mulched mixed m ulched mixed L 5« o m ulched m ixed L 7.5 i_< • o • u . F e rtilized Lime No l i m e Not f e r t i l i z e d Lime No l i m e 1 6 2 .2 l 8 0 .0 165.5 2 1 4 .5 193.5 228.8 161.7 1 2 3 .6 11+8.7 179.5 218.7 163.7 141.4 174.7 176.5 221.5 155.2 199.7 170.0 218.5 84.5 6 . 39: 5% - Average 1% 1 3 2 . 6* 1 7 3 .8 103.1 2 0 1 .2 164.7 195.2 1 7 6 .0 20/+.5 7 6 .0 1 9 2 .3 1 6 7 .9 - 8.1+6 TABLE 11+ EFFECT OF MULCHING, FERTILIZER AND LIMING ON THE USE OF "LIGNIN" — MIAMI SANDY LOAM SOIL M u lc h e d Y i e l d o f t o m a t o i n g r am s p e r p o t LimeM ixed F e rtiliz e d Not fertilized 132.6 L 0 No lim e 142.90 122.30 1 5 1 . 85 113.40 L 2.5 176.15 171.55 1 6 8 . 1+0 179.30 174.20 173.50 L 5*0 212.48 172.10 197.60 187.20 196,05 1 8 8 , 1+0 L 7.5 212.98 133.05 190.05 145.90 173.40 162,55 Ave. 2 0 0 .5 3 152.32 174.74 158.70 173.88 159.48 L «S • D. 5^ - 4.3 4 5.75 4e40 5.83 4.31 5.75 41 TABLE 1 5 EFFECT OF "LIGNIN” ON THE YIELD OF SPRING WHEAT GROWN ON MIAMI SANDY LOAM SOIL Grams p e r s i x p l a n t s F e rtilized Lime No l i m e L 0 L 2.5 L 5eO L 7 .5 'L. S .D . A verage Not f e r t i l i z e d Lime No l i m e 2.13 2.38 1.70 1.51 1.93* m ulched 3*4-5 2.75 1 .9 6 1.51 2.55 m ixed 3*20 2.91 2.29 2.38 m ulched 3.16 3.29 2.77 2.33 mixed 2.69 3.34 2.47 2.66 m ulched 2.47 3.39 1.85 2.36 mixed 2.08 3.27 1.73 1.51 5% - 0.105 - 0.135 2.89 2.33 A gain, t h e a v e r a g e y i e l d o f w h e a t g r o w n on " l i g n i n " - t r e a t e d s o i l was s i g n i f i c a n t l y h i g h e r t h a n o n t h e c o n t r o l so il. The i n c r e a s e s show a s i m i l a r t r e n d t o t h a t o b t a i n e d w i t h to m a t o - e s ( T a b l e 1 3 ) . M ulching and l i m in g , however, d i d n o t h a v e any f a v o r a b l e i n f l u e n c e on t h e i n c r e a s e s w h i c h r e s u l t e d f r o m ’’l i g n i n " ap p licatio n . This i s shown i n T able 1 6. From t h e s e two e x p e r i m e n t s , op timum r a t e of "lig n in " it se em s t h a t t h e a p p l i c a t i o n was f i v e t o n s p e r a c r e . C om parison o f t h e E f f e c t o f " L i g n i n " w i t h Ground C orncobs and Saw dust Used a s M u lch e s and a s M ix tu r e w i t h B r o o k s t o n C l a y Loam o n t h e Y i e l d o f T o m a t o e s a n d S p r i n g W heat A n o t h e r two e x p e r i m e n t s w e r e d e s i g n e d t o c o m p a r e t h e e f f e c t o f " l i g n i n " w i t h g ro u n d co rn co b s and saw dust which a r e o f t e n u s e d as m u lc h in g m a t e r i a l and m ixed w ith s o i l . T h e s e two e x p e r i m e n t s w e r e c a r r i e d o u t w i t h B r o o k s t o n c l a y loam s o i l u n d e r g re e n h o u s e c o n d i t i o n s . The t r e a t m e n t s in v o lv e d were as f o llo w s : Rate o f a p p l i c a t i o n 1. M aterial Check 1"»T. L- Ti g n i n " Ground c o r n c o b s Sawdust 3 to n s p e r acre 5 to n s p e r acre 5 tons p er acre 2. F e r t i l i z e r s 061218 - 12-12 12-12 1 2 -1 2 12-12 1000 1000 1000 1000 lb s. per lb s . per lb s. per lb s. per acre acre acre acre Nq N2 TABLE 1 6 EFFECT OF MULCHING, FERTILIZER, AND LIMING ON THE USE OF nLIGNIN” — MIAMI SANDY LOAM SOIL Y i e l d o f s p r i n g w h e a t - gr am s p e r s i x p l a n t s M ulched M ix e d F e rtilized Not fertilized Lime No lim e 2.28 1.60 1.9i|- 1 .94 2.79 3 .1 8 2.02 2.83 2.38 2.89 2.79 3.12 2,56 2.77 2.91 L 7 .5 2.50 2.15 2 .8 1 1.86 2.09 2.65 A ve. 2.45 2okl 2.85 2.01 2.142 2.47 L 0 1.94 L 2 ,5 2 .ip. L 5.0 L .S .D . % 0.079 0 . 08l 0.079 1% OolO< 0.108 0 .105 kk C. E x p e r i m e n t w i t h T o m a t o e s o n B r o o k s t o n C l a y Loam E f f e c t o f t h e d i f f e r e n t o r g a n ic m a t e r i a l s , w i t h and w i t h o u t n i t r o g e n on t h e y i e l d o f to m a to e s i s shown i n T a b l e 17. The r e s u l t s of th is e x p e r im e n t (T a b le 17) i n d i c a t e t h a t th e a p p l i c a t i o n o f sawdust to s o i l d e c r e a s e s th e tom ato y i e l d . A llison d e p r e s s iv e e f f e c t o f sawdust to c o n stitu en ts, such as ta n n in s , an i n c r e a s e i n s o i l acid ity , sig n ifican tly (1) a t t r i b u t e d the the f o rm a tio n o f t o x i c resin s, and t u r p e n t i n e , to and t o t h e d e p l e t i o n o f a v a i l ­ able n itr o g e n . The a v e r a g e y i e l d s o f t o m a t o e s o n s o i l s t r e a t e d w i t h c o r n c o b s a n d '’l i g n i n ” w e r e n o t s i g n i f i c a n t l y l a r g e r t h a n t h e y w ere on t h e c o n t r o l s o i l s . It s h o u l d b e n o t e d , " how­ e v e r , w hen n i t r o g e n w as s u p p l i e d a t a r a t e o f 18 0 p o u n d s per acre, t h e to m a to y i e l d s o f " l i g n i n " - t r e a t e d s o i l were s i g n i f i c a n t l y i n c r e a s e d over th o s e o b ta in e d where " l i g n i n ” was n o t a p p l i e d b u t w h e r e n i t r o g e n was a p p l i e d , , D« E x p e r i m e n t w i t h S p r i n g W hea t on B r o o k s t o n C l a y Loam A s i m i l a r e x p e r i m e n t was c a r r i e d o u t u s i n g s p r i n g wheat and t h r e e l e v e l s o f n i t r o g e n f e r t i l i z e r . of th ree re p lic a tio n s The r e s u l t s a r e shown i n T a b l e 1 8 • The r e s i x l t s o f t h e e x p e r i m e n t i n d i c a t e a p p l i c a t i o n o f " l i g n i n ” , ground co rn co b s, ( T a b l e 18 ) t h a t and saw dust s i g n i f i c a n t l y in c r e a s e d the y i e l d o f s p rin g w heat. A k5 TABLE 1 7 COMPARISON OP THE EFFECT OF "LIGNIN'', SAWDUST, AND GROUND CORNCOBS ON THE YIELD OF TOMATO PLANTS GROWN ON BROOKSTON CLAY LOAM: s o i l C h ec k No m ulche d Grams p e r p o t Corncobs Sawdust 126 II4I m ulched 1 70 m ixed n2 m ulched 261 m ixed n3 m ulched 278 m ixed Average L .S .D . 2 0 6 .1 % - 15.83 ; 1% 111+ 90 113 80 113 2i+0 191 161 11+9 l i +0 181+ 267 21+1 222 228 187 23k 281 17 9 329 293 263 316 207.3 1 7 0 .1 209*1 mixed N1 "Lignin" - 2 0 . 96 TABLE 18 COMPARISON OF THE EFFECT OF "LIGNIN", SAWDUST, AND GROUND CORNCOBS ON THE YIELD OF SPRING WHEAT GROWN ON BROOKSTON CLAY LOAM SOIL C hec k Nq N^ N2 m ulched m ixed m ulched 3.21+ 3.32 Grams p e r s i x p l a n t s Corncobs Sawdust "L ignin" 1+.23 2.93 5 .1 9 m ixed m ulched m ixed 3.71+ 3.71+ 3 .8 1 1+.02 Average 3.1+3 3.99 3.37 3.16 If . 63 3.76 1+.18 3.99 3*1+7 2.98 !+• 69 l+o 61+ 4*52 1+.1+7 3.73 1+.25 Ij.6 com parison o f th e r e s u l t s from t h e s e t h r e e m a t e r i a l s show t h a t a v e r a g e y i e l d o f w h e a t was h i g h e s t o n " l i g n i n ,,- t r e a t e d so il, i n t e r m e d i a t e o n c o r n c o b - t r e a t e d s o i l an d l e a s t on t h e saw dust-treated s o il . M ulching i n t h i s experim ent r e s u l t e d i n y i e l d s d e f i n ­ itely?- h i g h e r t h a n w e r e o b t a i n e d w h e r e t h e m a t e r i a l s w e r e m ixed w i t h s o i l a t a low n i t r o g e n l e v e l . n itrogen le v e l, however, i n g w a s l e s s marl® d . At t h e h i g h e s t th e d i f f e r e n c e i n f a v o r of m ulch­ V. FIE L D STUDIES An e x p e r i m e n t d e s i g n e d t o c o m p a r e v a r i o u s m u l c h i n g m a t e r i a l s was c a r r i e d o u t i n t h e f i e l d . The e x p e r i m e n t was l o c a t e d o n M e t e a l o a m y s a n d s o i l on t h e M i c h i g a n S t a t e C o l l e g e Farm a t E a s t L a n s i n g , M i c h i g a n , p l a n t e d o n J u n e 9, 1 9 5 2 , Soybeans were i n 28 i n c h rows lL). f e e t l o n g . T h e r e w e r e f o u r ro w s i n e a c h p l o t . On J u n e 25» 0 - 2 0 - 2 0 a t t h e r a t e o f 1000 pounds p e r a c r e was s i d e d r e s s e d and e n o u g h ammonium n i t r a t e t o make f o u r l e v e l s o f n i t r o g e n w as a p p l i e d b y b r o a d c a s t i n g . The n i t r o g e n a p p l i e d w as enough t o r a i s e t h e 0 - 2 0 -2 0 g ra d e t o g r a d e s c o n t a i n i n g 0, 6 , 12, 18 p e r c e n t n i t r o g e n , resp ectiv ely . Ground c o r n ­ c o b s , wheat s tr a w and saw dust w ere a p p l i e d as m ulches a t a rate o f f iv e to n s p e r a c r e . th re e tim es, The f i e l d w as c u l t i v a t e d tw ic e b e f o r e and once a f t e r th e m u lch in g . The b e a n s o f t h e c e n t r a l two rows w e r e h a r v e s t e d on O c t o b e r 7« The a v e r a g e y i e l d s o f s h e l l e d b e a n s a r e shown i n T able 1 9, The r e s u l t s o f t h i s experim ent i n d i c a t e t h a t th e use o f m ulch w i t h o u t n i t r o g e n a p p l i c a t i o n h a d a d e p r e s s i n g e f f e c t on t h e y i e l d o f s o y b e a n s . at a rate o f 60 pounds p e r a c r e , was m i n i m i z e d . When n i t r o g e n was a p p l i e d the d epressive e f f e c t A s l i g h t i n c r e a s e i n y i e l d by m ulching w i t h t h e e x c e p t i o n o f w h e a t s t r a w w a s o b t a i n e d when 12 0 48 TABLE 19 EFFECT OF VARIOUS MULCHING MATERIALS ON THE YIELD OF SOYBEANS GROWN ON METEA LOAMY SAND SOIL Ch ec k Grams p e r two rows Corncobs W h eat straw Sawdust Average No 100 7 79 4 816 817 858 Nl 1085 1085 1072 1079 1080 N2 1167 1280 1245 1188 1220 N3 1313 1329 1294 1345 1320 Ave, 1143 1122 1107 1107 k -9 a n d 1 8 0 p o u n d s o f n i t r o g e n p e r a c r e w as a p p l i e d , O thers ( Ip8 , 60) h a v e o b s e r v e d s i m i l a r d e p r e s s i n g r e s u l t s i n y i e l d w hen no n i t r o g e n was a d d e d . The f a c t o r s c a u s i n g t h e d e c r e a s e i n y i e l d by m u lc h in g a t low s o i l nitrogen le v e ls can be summarized as f o ll o w s : 1 . reduction of n itr a te p ro d u ctio n 2 . r e ta r d e d accum ulation of n i t r a t e (58> 39) in s o il ( 11+, 2 7 , 29, W 3 . d e c re a se i n t o t a l exchangeable b a s e s (59) I4.. i n c r e a s e d b i o l o g i c a l a c t i v i t y i m m o b i l i z e s t h e a v a i l ­ able n itro g e n in s o il ( 2 1 , ij.0 ) 5 . p re s e n c e o f to x ic s u b sta n c e s in m ulching m a te r ia l (1, 56) 60 i n c r e a s e i n s o i l a c i d i t y F avorable e f f e c ts (1 ) o f m ulching have a ls o been r e p o r t e d such as i n c r e a s e i n r e p l a c e a b l e p o ta ss iu m und er straw m u l c h ( 7 , 8 , 7 3 > 7 ^4-) a n d i m p r o v e m e n t i n p h y s i c a l p r o p e r t i e s of s o il. The r e s u l t s of th is f i e l d e x p e r i m e n t t e n d t o show t h a t w h e n no n i t r o g e n was a d d e d t h e d e t r i m e n t a l e f f e c t s o f m u lc h in g masked th e b e n e f i c i a l e f f e c t s . n i t r o g e n was a p p l i e d , When s u f f i c i e n t the depressive e f f e c ts , as p o in te d o u t ab o v e , w ere r e d u c e d and a s l i g h t i n c r e a s e i n y i e l d was o b t a i n e d i f 1 8 0 p o u n d s o f n i t r o g e n p e r a c r e was a d d e d . V I. S u r f a c e s o i l f r o m Miami SUMMARY sandy loam , w e l l m ixed w i t h " l i g n i n " loam and B r o o k s to n c l a y a t 0, 2 . 5 , 5*0, a n d 7*5 to n s p e r a c r e and w i t h m o is t u r e m a i n t a in e d a p p r o x im a te ly a t m o i s t u r e e q u i v a l e n t f o r f i v e weeks w e re b r o u g h t t o the la b o r a to r y f o r s tu d ie s of t h e i r p h y s ic a l, chem ical, an d b i o l o g i c a l p r o p e r t i e s . The a d d i t i o n o f " l i g n i n " t o s o il in c re a se d th e aggre­ g a t e s g r e a t e r t h a n 0 o25 m i l l i m e t e r , p e rc e n t m oisture at m o istu re e q u iv a le n t, hygroscopic c o e f fic ie n t,, p l a s t i c lim its, s t i c k y p o i n t a n d a m ount o f a v a i l a b l e w a t e r . also in creased p ercen t p o r o s itie s It at various ten sio n s and d e c r e a s e d p e r c e n t c a p i l l a r y p o r o s i t y . M ixing " l i g n i n " w i t h s o i l i n c r e a s e d s l i g h t l y t h e b ase exchange c a p a c i t y , buffer action, pH a n d e x c h a n g e a b l e p o t a s s i u m w h e re a s t o t a l and a d s o rb e d p h o s p h a te , exchange- c a l c i u m , m a g n e s iu m an d s o d iu m w e r e n o t a f f e c t e d . I n g r e e n h o u s e e x p e r i m e n t , Miami s a n d y lo a m s u r f a c e s o i l p r o d u c e d h i g h e r y i e l d s o f to m a to e s and s p r i n g w heat on " l i g n i n " - t r e a t e d so ils. The a v e r a g e y i e l d was h i g h e s t on s o i l w h i c h r e c e i v e d f i v e t o n s p e r a c r e o f " l i g n i n " . A p p l i c a t i o n o f f e r t i l i z e r a n d l i m e and m u l c h i n g i n c r e a s e d the e ffe c tiv e n e s s of " lig n in " on t h e y i e l d I n c r e a s e o f t o m a t o e s b u t t h e l a t t e r two d i d n o t m a t e r i a l l y a f f e c t t h a t o f s p rin g w heats 5o A c o m p a r i s o n b e t w e e n t h e e f f e c t o f g r o u n d c o r n c o b s , s a w d u st and " l i g n i n " (at fiv e m ulch and m ixed w ith s o i l to n s p e r a c r e ) u se d as o n t h e y i e l d o f t o m a t o an d s p r i n g w h e a t was s t u d i e d o n B r o o k s t o n c l a y l o a m s u r f a c e s o il i n the greenhouse. w as p r e f e r a b l e so il. t^ The r e s u l t s s h o w e d t h a t ’’l i g n i n " c o r n c o b s a n d s a w d u s t w hen m i x e d w i t h When u s e d a s m u l c h e s , "lignin" and c o r n c o b s were p r e f e r a b le to saw dust. 6 0 M ixing t h e s e m a t e r i a l s w i t h s o i l s r e s u l t e d i n d e c r e a s e d y ield s. The l e a s t d e p r e s s i o n o c c u r r e d w i t h " l i g n i n " . The d e p r e s s i v e e f f e c t g r a d u a l l y d i s a p p e a r e d a s t h e r a t e of nitrogen, a p p lic a tio n in c re a se d . 7 . The e f f e c t o f s a w d u s t , w h e a t s t r a w a n d g r o u n d c o r n c o b m u l c h e s on t h e y i e l d o f s o y b e a n s w a s s t u d i e d on. t h e M etea loamy s a n d s o i l a t t h e M ic h ig a n S t a t e C o l l e g e Farm, E a s t L a n s i n g , M ic h i g a n . The r e s u l t s in d icated t h a t w hen no n i t r o g e n was a p p l i e d t h e y a l l decreased the y ie ld of soybeans. T he d e t r i m e n t a l e f f e c t was i n t h e f o llo w in g o r d e r : w heat s tra w = saw dust > ground corncobs. The d e p r e s s i v e e f f e c t was m i n i m i z e d when n i t r o g e n was a p p l i e d a t a r a t e W her e 1 2 0 , added, o f 60 p o u n d s p e r a c r e . and l 8 0 pounds o f n i t r o g e n p e r a c r e were a n i n c r e a s e i n s o y b e a n y i e l d w as o b t a i n e d . 1 vri. CONCLUSIONS ’’L i g n i n ” p r o d u c e d f r o m s a c c h a r i f i c a t i o n o f c o r n c o b s im p ro v e d b o t h t h e p h y s i c a l and c h e m i c a l p r o p e r t i e s o f the su rfa c e so ils f r o m Miami s a n d y l o a m a n d B r o o k s t o n c l a y loam . The i n c o r p o r a t i o n o f ’’l i g n i n " n itro g e n but to depletes av ailab le so il a l e s s e r e x t e n t t h a n was t h e c a s e w i t h ground corn co b s and s a w d u st. On t h e a v e r a g e , "lig n in " applied at a r a te of f iv e tons p e r a c r e gave th e h i g h e s t y i e l d o f b o th t h e to m ato and s p r in g wheat under greenhouse c o n d itio n s . 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