USDA-A RS, Southern Piedmont Conservation Research Center, Watkinsville, GA 30677 Contributors Field Programs Branch, Tennessee Valley Authority Environmental Protection Agency Georgia Commodity Commission for Soybeans

Proceedings

of the

1985

Southern Region

No-Till Conference

July 16-17, 1985 Griffin, Georgia

Edited by

W. L. Hargrove and F. C. Boswell

Agronomy Department, Georgia Agricultural Experiment Station, Experiment, GA 30212

and

G. W. Langdale

USDA-ARS, Southern Piedmont Conservation Research Center, Watkinsville, GA 30677

Contributors

Field Programs Branch, Tennessee Valley Authority

Environmental Protection Agency

Preface

The objective of the Southern Region No-Tillage Conference i s t o

promote no- tillage production systems

by

providing a means

of

communication between research, extension, conservation, and

industry personnel and agricultural producers from the thirteen

s t a t e s

i n

the Southern region.

"The Rising Hope of O u r Land"

i s

from

the preamble t o the charter

of

the University

of

Georgia

written by Abraham Baldwin

i n

1785.

I n

t h i s year

of

the

Bicentennial

of

the University,

i t

i s a

f i t t i n g

theme

f o r

t h i s

Conference.

Not only does

i t

verbally symbolize the College

of

Agriculture and i t s resources

i n

teaching, research, and service,

b u t i t

expresses the hope

of

success

i n

soil conservation

and

productivity offered

by

no- tillage production methods

-

hope for our

land, for o u r farmers, for our future.

The f i r s t no- tillage conference was held among seven

southeastern s t a t e s

i n 1978

and was hosted

by

the Georgia

S t a t i o n .

This year marks a new beginning

w i t h

an expanded conference, which

includes a l l thirteen s t a t e s

i n

the Southern region. The Georgia

Station

i s

honored t o be the s i t e

of

the 1985 conference.

I t i s our

hope t h a t t h i s publication

will

be effective

i n

accomplishing the

objective

of

the conference.

W.

L.

Hargrove

Associate Professor,

UGA

F. C.

Boswell

Professor,

UGA

Soil Scientist

Conservation Tillage: National, International, and Future Prospects

No-Till

in

the Lowland Humid Tropics

La1

. . .

2 3 5

The Future of No-Tillage

63

Functions of Legume Cover Crops in No-Till

and Conventional Till Corn Production

M. Utomo, W. W. Frye, and R. L. Blevins

Department of Agronomy, University of Kentucky, Lexington, KY 40546-0091

Legumes are i m p o r t a n t i n c r o p p r o d u c t i o n due t o t h e i r c a p a b i l i t y o f f i x i n g atmospheric n i t r o g e n . I n a d d i t i o n t o s u p p l y i n g b i o l o g i c a l l y f i x e d N

t o t h e c o r n , t h e y add o r g a n i c matter, affect t h e supply o f a v a i l a b l e water and p l a n t n u t r i e n t s , improve t h e p h y s i c a l p r o p e r t i e s o f t h e s o i l , and p r o v i d e e r o s i o n c o n t r o l

(3).

I n Kentucky, research conducted from 1977 through 1983 ( 1 , 3 ) showed t h a t w i n t e r annual legumes could be grown as c o v e r crops i n a continuous n o - t i l l c o r n system. Hairy v e t c h r e s u l t e d i n t h e greatest y i e l d s of corn g r a i n , because it produced more d r y matter, t h u s more mulch, and h i g h e r

n i t r o g e n c o n t e n t t h a n t h e o t h e r c o v e r crops. The p l o t s used f o r t h e above experiment were s p l i t i n 1984, and one- half of each p l o t was c o n v e n t i o n a l l y

t i l l e d . The o b j e c t i v e s of t h i s were t o (a) determine t h e effects o f legume

c o v e r crops i n b o t h c o n v e n t i o n a l till and n o - t i l l systems, ( b ) compare t h e

e f f e c t s o f c o n t i n u o u s n o - t i l l w i t h t h a t o f p e r i o d i c c o n v e n t i o n a l t i l l a g e f o l l o w i n g s e v e r a l y e a r s o f n o - t i l l , and ( c ) e v a l u a t e t h e system under h i g h e r

rates o f f e r t i l i z e r N t h a n was used p r e v i o u s l y .

MATERIAL AND METHODS

The experiment was conducted a t Lexington, Kentucky on a Maury s o i l ( f i n e - s i l t y , mixed, mesic, Typic P a l e u d a l f ) . The p l o t s were e s t a b l i s h e d i n 1976 and maintained through 1983 under a system o f c o n t i n u o u s n o - t i l l c o r n

w i t h annual legumes as c o v e r crops ( 1 ) . I n 1984 t h e p l o t s were s p l i t i n t o c o n v e n t i o n a l till and n o - t i l l t r e a t m e n t s . The w i n t e r c o v e r c r o p s were overseeded i n mid-September 1983 i n t o t h e s t a n d i n g n o - t i l l corn. Cover t r e a t m e n t s were h a i r y v e t c h a l o n e , h a i r y v e t c h mixed w i t h annual r y e g r a s s ,

b i g f l o w e r v e t c h , rye, and c o r n r e s i d u e a l o n e . The annual r y e g r a s s

w i n t e r - k i l l e d l e a v i n g a pure s t a n d o f h a i r y v e t c h , therefore, r e s u l t s from

66

180

160

140

120

100

80

60

40

20 0

6/28 7/27 5/25? 6 / 2 8 7/27

S o i l Depth = 7.5 - 15

cm

170 - HV - CT 170-HV-NT

L

F i g . 1. A v a i l a b l e s o i l n i t r o g e n

+

o f n o - t i l l a g e and c o n v e n t i o n a l

t i l l a g e , 1984. h a i r y v e t c h ? CR c o r n r e s i d u e ; and 0

o f f e r t i l i z e r ; B e f o r e N f e r t i l i z e r a p p l i e d ) .

100 k g / h a / y r N estimated by E b e l h a r e t al. (1) from g r a i n y i e l d s and based

on f e r t i l i z e r N e q u i v a l e n t , b u t i t d o e s n o t take i n t o a c c o u n t m i n e r a l i z a t i o n o f s t o r e d s o i l o r g a n i c N. We p r e s e n t l y d o n o t have a r e l i a b l e estimate of t h a t .

Legumes as Mulch

The mulch from k i l l e d w i n t e r c o v e r c r o p s a f f e c t s s o i l t e m p e r a t u r e , s o i l m o i s t u r e , and s o i l e r o s i o n . Maximum and minimum s o i l t e m p e r a t u r e s were measured d a i l y a t 5-cm d e p t h d u r i n g t h e f i r s t month a f t e r p l a n t i n g t h e c o r n .

The a v e r a g e maximum s o i l t e m p e r a t u r e s , measured both i n row and between row, were c o n s i s t e n t l y l o w e r u n d e r n o - t i l l t h a n c o n v e n t i o n a l till. However, n o - t i l l m a x i m u m s o i l t e m p e r a t u r e s u n d e r c o r n r e s i d u e , r y e , and h a i r y v e t c h were 1.9, 1.8, and 3.6 C, r e s p e c t i v e l y , h i g h e r when measured i n t h e row