Project Overview
Commodities
- Agronomic: clovers, cotton, millet, peas (field, cowpeas), rye, vetches, wheat
- Animals: bovine, goats, sheep
Practices
- Animal Production: grazing management, grazing - multispecies, rangeland/pasture management
- Crop Production: cover crops, nutrient management
- Production Systems: integrated crop and livestock systems
- Soil Management: organic matter, soil quality/health
Abstract:
Legume cover crops have potential to offset N fertilizer inputs, provide a high-value supplemental forage source for the regional livestock industry, and improve the health of agricultural soils in the Southern Rolling Plains and Permian Basin of western Texas. The fallow period between harvesting wheat and planting cotton often exceeds eight months (July–February), and the fallow period in continuous wheat systems is generally July–October. Annual precipitation in this region has a bimodal distribution, with the majority of rainfall occurring in the late spring (April, May, June) and early fall (August, September, October). The fallow periods in wheat–cotton and wheat–wheat systems are a valuable opportunity to take advantage of fall precipitation and grow a cover- or dual-use-crop.
The efforts of this project expanded upon the work of SARE project OS19-131 to investigate management options for legume cover crops in continuous winter forage, wheat (or grain sorghum)-cotton, and continuous cotton systems. Successful cover crop management can contribute surface residue, soil organic matter, and organic N, reducing fertilizer input costs. In addition to potential agronomic benefits and soil health, many cultivated legumes are high-protein forage crops that may offer dual-use potential in integrated animal systems. Texas is the leading state in goat, sheep, and cattle production for the U.S. All three of these livestock species are major regional enterprises in western Texas. Many cotton and wheat farmers also manage livestock on native rangeland or improved pasture, and wheat is often managed in a dual-use system to provide winter grazing, as well as a grain crop. The proposed cover crop practices could provide a high-quality forage source to supplement livestock production during critical periods, although optimum species and seeding rates are unknown.
Warm-season cover crop species of interest include different varieties of cowpea (Vigna unguiculate (L.) Walp.) and sunn hemp (Crotalaria juncea L.). Cool-season cover crops (in continuous cotton) include hairy vetch (Vicia villosa), Austrian winter pea (Pisum sativum L. ssp. sativum var. arvense), and Silver River sweetclover (Melilotus albus). Growing these cover crop species in a biculture with common grass crops such as cereal rye (Secale cereale L.) in the winter and pearl millet (Pennisetum glaucum (L.) R. Br.) in the summer may provide greater biomass, benefit to the soil, and potential forage. This work consisted of 10 field research trials (2 in summer 2020, 5 in winter 2020-2021, and 3 in summer 2021) on growers farms across West Central Texas. Key findings highlight the potential to maintain biomass production with reduced cover crop seeding rates (both warm- and cool-season), improving economic efficiency and reducing the risk of cover crop investment in this environment. However, the lowest seeding rate correlated with greater weed biomass in the warm-season cover crops. Inclusion of a grass species enhanced overall biomass production across systems, and also reduced weed biomass in the warm-season cover crops. Key annual legume species identified as best-adapted to our region were Austrian winter pea (cool-season) and sunn hemp and 'Iron & Clay' cowpea (warm-season). Findings have been communicated to grower audiences via Extension outlets, and multiple current and future grower collaborators have implemented cover crop practices on their farms based on our findings.
Project objectives:
The objectives of this research are to:
- Assess adaptability and production potential of both warm and cool season legume options as cover/forage crops in West Central Texas annual crop rotations.
- Determine economically optimum seeding rates according to legume species and variety.
- Assess the effect of including a grass in mixture with the legume (rye in winter and millet in summer).
- Observe and quantify any effects on subsequent crop growth.