Considerations for Managing Cover Crops. Andrew Price USDA-ARS-NSDL

Transcription

1 Considerations for Managing Cover Crops Andrew Price USDA-ARS-NSDL

2 Considerations for Managing Cover Crops Andrew Price USDA-ARS-NSDL

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7 + Facilitates increase of soil quality and subsequent productivity Protects against soil water and wind erosion Decreases moisture loss Reduces fuel and time Potential that cover crop residue can suppress weed emergence and growth Facilitates increased weed seed predation and weathering Conservation Agriculture - Provides trashy seedbed that requires management knowledge Potential that cover crop residue can suppress crop growth Accumulates weed seed on & near soil surface Provides cooler early spring soil temperature Eliminates broadcast preplant incorporated application; residue intercepts preemergence application Eliminates conventional cultivation NSDL file picture

8 Comparison of mechanical and chemical winter cereal cover crop termination systems and cotton yield in conservation agriculture.

9 Comparison of mechanical and chemical winter cereal cover crop termination systems In the spring, the covers were terminated 3 wk prior to cash crop planting with either: a mechanical roller alone; glyphosate at 0.75, 0.38, 0.19, or 0 lb ae/ac alone; or a mechanical roller followed by each rate of glyphosate. a non-treated check was included to complete the factorial treatment arrangement. Price, A. J., F. J. Arriaga, R. L. Raper, K. S. Balkcom, T. S. Kornecki, and D. W. Reeves Comparison of mechanical and chemical winter cereal cover crop termination systems and cotton yield in conservation agriculture. Cotton Sci. 13:

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12 Conclusions Rolling applied to mature rye can increase termination up to 20% compared to reduced glyphosate rates alone or up to 47% compared to non-treated plots. Rolling followed by reduced glyphosate rates as low as 0.38 lb ae/ac can effectively and reliably terminate a mature winter rye cover. Reduced glyphosate rates as low as 0.38 lb ae/ac alone may effectively terminate immature cereal covers.

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14 Conservation Agriculture 100 Amount of PRE reaching soil kg/ha ~ 50% interception 4000 kg/ha ~ 75% interception 8000 kg/ha > 90% interception Amount of Biomass (kg/ha) Banks and Robinson (1982)

15 Do herbicides wash-off cover crop residues with irrigation? 110 y = 99e x (R 2 = 0.70) pendimethalin With a 12.5 mm irrigation event, approximately 13% of the metolachlor and 0.6% of the pendimethalin washes off the cover crop residue y (100 - cumulative %-loss) 90 13% Metolachlor % Pendimethalin y = 92e x (R 2 = 0.61) metolachlor x (cumulative rainfall; mm) Potter et al J. Envrion. Qual. 37:

16 Conservation Agriculture Recognition that reduced tillage accelerates buildup of seed of weed species less susceptible to applied herbicides points to the importance of maintaining acceptable levels of weed control in reduced-tillage systems beyond that necessary in systems utilizing moldboard plows. Ball (1992). It is also likely that development of herbicide-resistant weed populations will be more rapid in reduced-tillage systems due to the potential for rapid seedbank increases when control cannot be maintained. NSDL file picture

17 Weed biomass (lb/a) Weed biomass in conservation-tilled soybean as affected by cover crop and herbicide regime (51 DAP) Price, A. J., D. W. Reeves, and M. G. Patterson Evaluation of three winter cereals for weed control in conservation-tillage non-transgenic soybean. Renewable Agric. and Food Sys. 21: LSD 0.1 = 1276 lb/a Black oat Wheat Rye Fallow 0 None Low High Herbicide regime

18 Cover Crops as a Mulch Exclude light needed for weed seed germination and growth Act as physical barrier to weed growth 4 inches Thicker mulches work better at suppressing weeds

19 Cover Crop Planting and Termination 5 cover crop planting dates; 4 termination dates Corn and cotton cash crop rotation Clover cover crop preceding corn; Rye cover crop preceding cotton Weed biomass evaluated at 4- leaf (cotton) and 8-leaf (corn) growth stage prior to POST herbicide application

20 Rye Planting and Termination Rye biomass (kg/ha) Cover crop planted 4 or 2 weeks before, at (0), or 2 or 4 weeks after average frost Terminating cover crop 1, 2, 3 or 4 weeks before planting Estimate of rye biomass (kg/ha)

21 Rye Planting and Termination Weed suppression in cotton Weed biomass (kg/ha)

22 Clover Planting and Termination Clover biomass (kg/ha)

23 Clover Planting and Termination Weed suppression in corn Weed biomass (kg/ha)

24 Cover Crop Planting and Termination Well-established covers suppress weed growth An earlier planting date and later termination date increases cover biomass and decreases weed biomass winter and summer weeds

25 Building Mulch Current clover cover crop Cotton residue from last fall Rye residue from last spring Corn residue from 1 1/2 yr ago!

26 Methods and Materials 5 management systems 3 winter rye conservation-tillage 1 winter fallow conservation-tillage 1 conventional tillage 4 herbicide regimes PRE broadcast fb POST fb LAYBY PRE banded fb POST fb LAYBY POST fb LAYBY LAYBY alone 2 locations (EVS & TV)

27 Results and Discussion

28 Early Palmer Amaranth Density by Treatment - E.V. Smith 2007 Rye Biomass (kg/ha) PD1 PD2 PD3 CT WF Density (plants/ha) Rye Palmer Amaranth Cover Crop Treatment Late Palmer Amaranth Density by Treatment - E.V. Smith 2007 Rye Biomass (kg/ha) PD1 PD2 PD3 CT WF Density (plants/ha) Rye Palmer Amaranth Cover Crop Treatment PD1 PD2 PD3 CT WF Rye Seed Cotton Price, A. J., K. S. Balkcom, L. M. Duzy, and J. A. Kelton Herbicide and cover cop residue integration for Amaranth control in conservation agriculture cotton. Weed Technol. 26:

29 Materials and Methods Location E.V.S Research Station, AL Experimental design Split-split-split plot Replication Three Plot size Main-plot 60 x 9.1 meter Subplot 15 x 9.1 meter Sub-subplot 3.6 x 9.1 meter No-Inversion Inversion Rye Clover Fallow No-Herbicide Pre alone Post alone Pre + Post

30 Treatments Cont Herbicide programs split in LL system No-Herbicide Only preemergence Prowl (2 Pt acre -1 ) + Reflex (1Pt acre -1 ) and Caparol (24 floz acre -1 ) plus MSMA (40 floz acre -1 ) LAYBY Only postemergence Ignite(29 oz/a) + Dual Magnum II (8 oz/a) and Caparol (24 floz acre -1 ) plus MSMA (40 floz acre -1 ) LAYBY Pre+postemergence

31 Palmer amaranth control under different tillage and herbicide programs 100 NONE PRE POST PRE+POST 80 % Control Inversion NO Inversion YES

32 Palmer amaranth control under different covers and herbicide programs 100 NONE PRE POST PRE+POST 80 % Control FALLOW CLOVER RYE

33 Conclusions Inversion tillage is avoidable Integration of cover crops and an effective PRE + POST herbicide regime with extended residual activity can effectively manage Palmer amaranth in a glufosinate-resistant cotton system Aulakh, J. S., A. J. Price, S. F. Enloe, E. Van Santen, G. Wehtje and M.G. Patterson Palmer amaranth management in glufosinate-resistant cotton: I. tillage system, cover crops and herbicide management. Weed Management and Herbicide Resistance Special Issue. Agronomy. 2: Aulakh, J. S., A. J. Price, S. F. Enloe, G. Wehtje and M.G. Patterson Palmer amaranth management in glufosinate-resistant cotton: II. primary, secondary, and conservation tillage. Weed Management and Herbicide Resistance Special Issue. Agronomy. 3:28-42.

34 Demonstrating Use of High-Residue, Cover-Crop Conservation- Tillage Systems to Control Glyphosate-Resistant Palmer Amaranth Funded NRCS Conservation Innovation Grant ($186,276) Multi-state collaborative agreement with objectives to: Demonstrate successful resistant pigweed control methods Promote adoption of high residue cover crop systems Provide successful model to producers incorporating this system Ensure conservation tillage remains a viable alternative to conventional tillage practices

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