12/20/2013
Adaptation Of Cover Crops In
The Texas Rolling Plains.
Paul DeLaune
Texas A&M AgriLife Research - Vernon
1
12/20/2013
Texas Rolling Plains

Chillicothe Research Station
Rainfall
◉ 46 to 76 cm; 56
to 66 cm
Smith/Walker

Monoculture
Cropping Systems
◉ Cotton
◉ Wheat (graze and
grain)

<15% of crop
acres irrigated
2
12/20/2013
Cover Crops in Texas Rolling Plains




Winter cover crops do not appear to be a viable option in the Rolling
Plains due to limited soil moisture for establishment and the removal
of soil moisture by cover crops will likely hinder subsequent crop
yields due to increased moisture deficit at planting (Dozier et al.,
2008).
Baughman et al. (2007) reported that cotton lint yields were reduced
in the Rolling Plains when a cover crop was used in combination with
no-till cotton.
Keeling et al. (1996) concluded that it could be expected to obtain a
protective ground cover 69% of the time in the Southern High Plains if
the proper species is sown and that fall rainfall is adequate for
germination and plant survival. Several legume species failed due to
inadequate moisture.
Dozier et al. (2008) concluded that legume cover crops do not
provide adequate biomass or N contributions to justify the seed and
planting costs.
3
12/20/2013
Cover Crops in Texas Rolling Plains

Research has noted higher soil moisture availability in conservation
tillage systems with cover crops compared to conservation tillage
systems without cover crops and conventional tillage systems in the
Rolling Plains (Sij et al., 2004).

Multiple year studies in the Rolling Plains have also shown no impact
of cover crops on cotton lint yields (Sij et al., 2004; DeLaune et al.,
2012).

Time of termination becomes more critical as the probability of
precipitation decreases (Unger et al., 1998).

Practices that are perceived to reduce the capability of soils to
capture rainfall will hinder adoption.
4
12/20/2013
Cover Crop Studies

Cool-Season cover crops in dryland cotton systems (Fall
2011; Chillicothe Research Station)

Cool-Season cover crops in irrigated cotton systems (Fall
2012; Chillicothe Research Station)

Warm-Season cover crops in dryland wheat systems &
intercrop (Summer 2013; Smith/Walker Research Unit)
5
12/20/2013
Methods

Soil samples (fall and spring)
◉ Nitrate, ammonium, TN, TC, SOC, MIII-P

Forage Samples
◉ Biomass, N content, C:N

Crop Yields

Soil Moisture
◉ Neutron Probes (140 cm; bi-weekly)
6
12/20/2013
Cool-Season Cover Crops in
Dryland Cotton (Fall 2011)
No-Till without a cover (1st year No-Till)
 No-Till without a cover + N
 No-till with cover

◉
◉
◉
◉
◉
Austrian winter field pea (39.2 kg/ha)
Crimson clover (16.8)
Hairy Vetch (22.4)
Wheat (33.6)
Sunn Hemp (16.8; Planted March 29, 2012)
Cover Plant Date – October 31, 2011; 4 reps/trt
 Termination Date – (4/30 legumes; 4/10 wheat; 5/31 Sunn
hemp)
 Cotton planted June 8, 2012 (DP 1044 B2RF)

7
12/20/2013
2011-2012 Drought Severity
May 3, 2011
July 5, 2011
May 8, 2012
July 10, 2012
Drought Severity
•Abnormally Dry
•Moderate
•Severe
•Extreme
•Exceptional
8
12/20/2013
Precipitation (cm)
2011
2012
Jan
0.02
0.53
Feb
0.61
1.09
March
0.02
4.95
April
0.00
3.88
May
6.39
2.03
June
1.12
7.89
July
0.25
3.63
August
0.38
8.22
September
1.04
11.59
October
6.62
0.86
November
3.37
0.03
December
3.30
Total
23.1
1.19
45.9
*Average Precipitation = 63 cm
9
12/20/2013
Austrian Winter Field Pea
Hairy Vetch
Crimson
Clover
Cover Crops
April 24,2012
10
12/20/2013
Biomass Production – Spring 2012
3000
Sunn Hemp
2500
A
Crimson Clover
Biomass (kg/ha)
Hairy Vetch
2000
AB
AWF. Pea
Wheat
BC
1500
C
1000
500
C
0
11
12/20/2013
Nitrogen Uptake - 2012
60
Sunn Hemp
50
A
Crimson Clover
AB
N Uptake (kg/ha)
Hairy Vetch
40
AWF. Pea
AB
Wheat
30
20
B
B
10
0
12
12/20/2013
Gravimetric Water Content*
0.06
0.058
Sunn Hemp
A
Crimson Clover
Grav. Water Content (kg/kg)
No-Till
0.056
0.054
0.052
0.05
No-Till 2
AB
AB
AB
Hairy Vetch
AWF. Pea
AB
Wheat
B
AB
0.048
0.046
0.044
*June 2012, 0-30 cm soil cores following 7.5cm precipitation
13
12/20/2013
14
12/20/2013
Cool-Season Cover Crops in
Cotton (Fall 2012)

No-Till without a cover
 Conventional Till without a cover
 No-till with cover
◉
◉
◉
◉
◉
Austrian winter field pea (39.2 kg/ha)
Crimson clover (22.4)
Hairy Vetch (22.4)
Wheat (33.6)
Mix (44.8 kg/ha: Rye-11.2, Wheat-11.2, Turnip-2.2, Crimson
clover-3.4, Austrian winter field pea-11.2, and Hairy vetch-5.6)

Terminated cover with glyphosate April 24, 2013
 Planted cotton June 6, 2013; DP 1219 B2RF
15
12/20/2013
Precipitation (cm)
2012
2013
Jan
0.53
1.98
Feb
1.09
7.84
March
4.95
0.03
April
3.88
4.54
May
2.03
2.43
June
7.89
9.26
July
3.63
11.03
August
8.22
2.38
September
11.59
1.62
October
0.86
0.51
November
0.03
-
December
1.19
45.9
41.6
Total
16
12/20/2013
February 12, 2013
17
12/20/2013
4/15/2013
18
12/20/2013
Biomass Production – Spring 2013
3000
Crimson Clover
2500
Wheat
A
Biomass (kg/ha)
Hairy Vetch
2000
A
AWF. Pea
Mixed
1500
AB
AB
1000
500
C
0
19
12/20/2013
Nitrogen Uptake - 2013
80
A
70
AB
N Uptake (kg/ha)
60
50
40
AB
30
20
10
B
B
0
20
12/20/2013
Stored Soil Water in Top 140 cm
310
Austrian pea
Conv. Till
Stored Soil Moisture (mm)
290
270
Crimson
clover
Hairy Vetch
Mixed cover
250
No-Till
230
210
*
190
Cover
Termination
170
150
12/5/2012
*
1/5/2013
2/5/2013
3/5/2013
4/5/2013
5/5/2013
6/5/2013
7/5/2013
8/5/2013
9/5/2013
10/5/2013
21
12/20/2013
Stored Soil Water in Top 60 cm
150
Austrian pea
Conv. Till
Crimson clover
Mixed cover
No-Till
wheat
Hairy Vetch
Stored Soil Moisture (mm)
140
130
120
110
100
90
80
70
60
50
22
12/20/2013
Dryland Cotton Yield - 2013
600
Lint Yield (kg/ha)*
500
AWF Pea
Mixed
Vetch
Conv. Till
Wheat
Crimson
400
B
B
AB
No-Till
AB
AB
A
AB
300
200
100
0
*Estimated turnout = 30%
23
12/20/2013
Cool-Season Cover Crops in
Irrigated Cotton (Fall 2012)

No-Till without a cover
 Conventional Till without a cover
 No-till with cover
◉ Wheat
◉ Mix (Rye, Wheat, Turnip, Crimson clover, Austrian winter field
pea, and Hairy vetch)

4 Replications per treatment
 Terminated with glyphosate April 24, 2013
 Plant Date June 3, 2013; DP 1219 B2RF
24
12/20/2013
April 20, 2013
March 29, 2013
25
12/20/2013
Biomass and N Uptake - 2013
80
4500
4000
A
Mixed
A
70
3500
60
Wheat
3000
50
2500
B
B
2000
40
30
1500
20
1000
10
500
0
0
Biomass
N Uptake
26
12/20/2013
Stored Soil Water in Top 140 cm
265
conv.Till
Stored Soil Moisture (mm)
mixed cover
245
No.Till
wheat
225
205
185
165
*
145
*
125
27
12/20/2013
Stored Soil Water in Top 60 cm
120
Stored Soil Water (mm)
110
100
90
80
70
60
*
conv.Till
mixed cover
50
*
No.Till
wheat
40
28
12/20/2013
Irrigated Cotton Yield - 2013
1400
Mixed
1350
Wheat
Lint Yield (kg/ha)*
Conv. Till
1300
No-Till
1250
1200
1150
1100
Estimated turnout = 35%
29
12/20/2013
Cover Crops in Wheat







Conventional till
No-till with no cover
No-till with no cover, intercropped (Turnip, Radish each @
0.56 kg/ha)
No-Till with mixed cover, no-graze
No-till with mixed cover, grazed
No-till with mixed cover, intercropped, no-graze
No-till with mixed cover, intercropped, grazed

4 reps; each plot 0.405 ha
 Planted Cover June 9, 2013
 Grazed August 26-29th; 15 pairs for 24 hours per .405 ha
30
12/20/2013
31
12/20/2013
Warm Season Cover Crop Mix in
Wheat at Vernon
Crop
Rate
(lb/ac)
Cost ($/lb)
Iron & Clay Cowpea
6
0.90
Catjang Pea
6
0.90
Lablab Bean
1
2.10
Forage Soybean
8
1.20
Browntop Millet
1.5
0.90
G. Foxtail Millet
1.5
1.00
Sorghum Sudan
2.5
0.68
Buckwheat
3
1.00
Sesame
0.5
2.10
Inoculant
-
1.75
Total
30 lb/ac $32.95/ac
32
12/20/2013
33
12/20/2013
Stored Soil Water in Top 140 cm
290
Stored Soil Water (mm)
280
270
260
250
240
230
220
210
ConvTill
NoTill
NT Cover/Graze
NT Cover/No graze
NT Cover/Graze/Intercrop
NT Cover/No Graze/Intercrop
NT No Cover/Intercrop
*
*
200
34
12/20/2013
Stored Soil Water in Top 60 cm
140
130
Stored Soil Water (mm)
120
110
100
*
90
*
80
70
60
50
ConvTill
NoTill
NT Cover/Graze
NT Cover/No graze
NT Cover/Graze/Intercrop
NT Cover/No Graze/Intercrop
NT No Cover/Intercrop
40
35
12/20/2013
Conclusions

Not all cover crops are equal, establishment can be difficult
depending on climatic conditions and management decisions.

Cover crops can use a significant amount of soil moisture.

However, loss of soil moisture due to cover crops during the
period prior to planting does not necessarily translate to
reduced cash crop performance.

Termination timing can be critical.

What’s in it for the producer? Time interval to expect benefits?
36
12/20/2013
37
Questions?
Paul DeLaune
940-552-9941 x207
[email protected]
37