Liming Acid Soils Is Essential for Ryegrass Forage Production

Transcription

Liming Acid Soils Is Essential for Ryegrass Forage Production
Louisiana
Liming Acid Soils Is Essential
for Ryegrass Forage Production
By M . M . E i c h h o r n and Paul Bell
Louisiana field research indicates the importance
ryegrass forage production.
Substantial
differences
and liming were recorded.
T H E E F F E C T S o f soil a c i d i t y o n
seven varieties o f ryegrass were studied
at the H i l l F a r m Research Station at
Homer, L A . I n i t i a l soil p H at the test
site was 4.2. Exchangeable a l u m i n u m
( A l ) was 118 parts per m i l l i o n ( p p m ) o n
the c o n t r o l plots at the outset o f the
study (Table 1).
Table 1. Effects of agricultural limestone on
soil pH and soil chemical properties.
Lime
Before Before After
Prior to
rate,
cropping harvest harvest planting
tons/A Aug '92 Nov '92 May '93 Aug '93
Soil pH 4.2
0
4.0
3.8
3.8
€4
4,4
4.4
1
2
4.9
4.9
5.2
•3.9
Sol
4
5.9
5.8
5.7
4.1
M
M
6.5
1
0
2
8
162
81
100
Exchangeable Ca, ppm
79
82
83
414
384
424
1,021
1,051
1,117
0
2
8
118
91
91
Exchangeable Al, ppm
106
83
114
24
24
26
2
1
3
Fine, h i g h q u a l i t y a g r i c u l t u r a l l i m e
(100.2 percent effective c a l c i u m carbonate equivalent) was applied at rates o f 1,
2, 4 and 8 t o n s / A i n A u g u s t 1992 and
incorporated t o a d e p t h o f 6 inches.
Ryegrass was drill-seeded i n October
1992. T h e crop received n i t r o g e n ( N ) ,
phosphorus (P), potassium ( K ) and sul-
of liming to correct soil acidity for
in varietal responses to soil acidity
f u r (S) f e r t i l i z a t i o n i n f o u r applications
f o r t o t a l rates o f 328 l b / A N , 162 l b / A
P 0 , 464 l b / A K 0 and 72 l b / A S. T h e
ryegrass was harvested seven times i n
the October 1992 t o M a y 1993 g r o w i n g
season: December 1, F e b r u a r y 1, Febr u a r y 24, M a r c h 25, A p r i l 13, M a y 3
a n d M a y 26.
2
5
2
Significant Results
Soil p H values were increased by a l l
rates, but l i m e application at 8 t o n s / A
was r e q u i r e d t o raise the soil p H t o
6.5 ( T a b l e 1 ) . L i m i n g s u b s t a n t i a l l y
increased exchangeable c a l c i u m ( C a )
a n d l o w e r e d exchangeable A l , w h i c h
c o n t r i b u t e d t o significant forage yield
responses at the lowest r a t e o f l i m e
application (Table 2).
Table 2. Effects of liming on Marshall ryegrass
dry matter yields.
Dry matter, lb/A
Lime
— Harvest
Total of
rate,
tons/A
1
7
7 harvests
3
5
2,812
0 124
819 283
0
658 869 1,519 673
8,723
1
9,672
709 936 1,606 719
8,142
868 757 1,679 646
8
793 821 1,678 914
8,828
L o w soil p H delayed harvests a n d
reduced yields. None o f the seven v a r i eties p r o d u c e d harvestable forage o n
the acid c o n t r o l plots at the f i r s t harvest
Dr. Eichhorn is Professor of Agronomy, L S U Agricultural Center, H i l l Farm Research
Station, Homer, L A ; Dr. Bell is Assistant Professor, Dept. of Agronomy, L S U Agricultural
Center, Baton Rouge, L A .
W
Better Crops/Fall
1993
GROWTH of ryegrass was severely limited where no lime was applied (at left). Plot shown at right
received 1 ton/A lime application, which increased yield and soil pH.
Summary
date. I n contrast, M a r s h a l l variety p r o duced 658 l b / A d r y matter at f i r s t harvest on plots receiving 1 t o n / A lime and
868 l b / A o n the 4 t o n s / A lime plots.
M a r s h a l l , Tetragold, Surrey and Jackson v a r i e t i e s p r o d u c e d s i g n i f i c a n t l y
higher yields w i t h l i m i n g t h a n d i d G u l f ,
F l o r i d a 80 and T X R - 9 1 - A 7 E F .
F a l l applications o f g o o d q u a l i t y agric u l t u r a l l i m e t o a c i d soils p r i o r t o
ryegrass seeding is an i m p o r t a n t m a n agement practice f o r acceptable forage
yields. L i m i n g increased soil p H ,
increased exchangeable Ca, l o w e r e d
exchangeable A l , advanced forage harvest and increased yields. •
Acid Tolerance . . . from page 9
was the most A l - t o l e r a n t legume i n that
it p r o d u c e d 60 percent o f the m a x i m u m
yield at p H 4.4 and 91 p p m A l , w h i l e
other legumes p r o d u c e d very l i t t l e
g r o w t h at that A l level. However, Serala
lespedeza p r o d u c e d more g r o w t h at 39
and 59 p p m A l t h a n d i d aeschynomene.
Serala also p r o d u c e d more g r o w t h t h a n
d i d Interstate 76 lespedeza at a l l A l
levels. A l y c e clover was the least A l tolerant species, p r o d u c i n g only 41 and
38 percent o f m a x i m u m yield at 39 and
59 p p m A l . None o f the legumes p r o duced significant g r o w t h at p H values
above 7.
Summary
Common bermudagrass and Marshall ryegrass w e r e b o t h t o l e r a n t o f
Better Crops/Fall 1993
highly acid and alkaline soil, although
ryegrass yield was severely depressed at
p H 4.6 and 111 p p m o f exchangeable A l .
Dallisgrass and bahiagrass were highly
A l tolerant, but yields were greatly
reduced i n alkaline soil. None o f the
l e g u m e s g r e w w e l l at a l k a l i n e p H
values. Cool-season clovers p r o d u c e d
m a x i m u m yields at p H 5.2 and 36 p p m
exchangeable A l w h i l e w a r m - s e a s o n
legumes, w h i c h are generally considered more acid tolerant, p r o d u c e d maxi m u m y i e l d s at p H 5.7 a n d 4 p p m
exchangeable A l . Reasons f o r these differences are b e i n g investigated. I t is
encouraging that legumes can be p r o ductive on this highly acid F l a t w o o d soil
w i t h as l i t t l e as 3 t o n s / A o f applied
lime. •
11

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