The Performance of Cover Crops in Minimally Til...

The Performance of Cover Crops in Minimally Tilled Forage-based Grazing Systems

The Performance of Cover Crops in Minimally Tilled Forage-based Grazing Systems

Introduction:

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Texas plays a major role in agriculture, especially in the beef industry. Cattle production is crucial to the Texas High Plains agriculture community, but production systems that jeopardize the sustainability of water use through the continued depletion of the Ogallala Aquifer put the industry and the vitality of rural communities at risk.

Forage-based livestock systems have proven to be economical and resource-efficient methods for High Plains agriculture. Long-term integrated crop/livestock systems help reduce overall water use and preserve soil health while maintaining marketable weight for animals that are proving profitable for farmers.

Integrating winter cover crops with summer forage crops could maximize land productivity and system profitability by improving water infiltration, stabilizing soils, and increasing additional potential income channels. However, adoption of cover crops has been slow because of concerns that cover crops withdraw soil water to the detriment of the summer crop, and they may not generate immediate economic benefits.

In a Southern SARE-funded Graduate Student Grant (GS15-152), “Evaluation of Winter Annual Cover Crops Under Multiple Residue Management: Impacts on land management, soil water depletion, and cash crop productivity,” Texas Tech University researchers investigated five cover crops species as potential complements to a warm-season beef-stocker grazing system. The impact of the project was two-fold: Stabilize the soil surface from excessive wind erosion and desiccation; and strengthen rural communities by ensuring the persistence of profitable agriculture in the region.

Research Summary:

The use of winter annual cover crops is very promising for the Texas High Plains. The five species selected for the study (rye, burr medic, hairy vetch, rape-kale, and wheat) were developed for or found to be adaptable to the Southern High Plains. The target uses of these cover crops serve the dual roles of stabilization and enhancement of soil plus their use as a grazeable spring forage.

The research investigated the interacting effects of irrigation and tillage with the five cover crops on soil water depletion and productivity of the cover and subsequent forage crop (teff) to identify the most successful cover crop practices in the drought-prone Southern High Plains.

Research Objectives:

Researchers compared the persistence and productivity of five winter cover crop species under four water and tillage treatment combinations for the ability to conserve soil water and promote growth of summer forages.

They also compared the residual effects of cover crops and winter management strategies on the productivity and nutrient status of a subsequent no-till, irrigated summer teff hay crop. Such effects could include nitrogen supplied by legumes, allelopathy from wheat and rye, and the depletion of soil water in the rooting zone.

Research Results:

Nodules on hairy vetch

Nodules on hairy vetch. Photo credit: Texas Tech University

The two-year study was conducted at the Texas Tech Research Farm in New Deal, TX. A 50 foot by 180 foot area was allocated to the small plot experiment with three replicate blocks. Two irrigation treatments, dryland and irrigation, were applied across all blocks.

Within each block, two tillage treatments (minimal and no-till) were arranged with the cover crop treatments. Treatments compared rye, wheat, burr medic, hairy vetch, rape-kale and an unplanted fallow.

Irrigation and Rainfall:

Rainfall was lower in the first year of the study than in the second year. As a result, there were differences in the way the cover crops performed between years as the crops were irrigated in the drier year to make up for the lack of moisture. Overall, researchers found that ground cover was greater in the first year when rainfall was higher. However, in the year where irrigation was used, winter cover crops did not require more irrigation than the winter fallow within each irrigation and tillage combination.

Cover Crop Yield:

Greater cumulative yields were observed in the first year compared to the second year. In the first year, the greatest yields were observed in rape-kale and irrigated rye (irrigated and dryland) and irrigated rape-kale, followed by dryland rape-kale. In the second year, the greatest cumulative yields were produced by irrigated rye, followed by irrigated hairy vetch and dryland rye, then wheat (both irrigation regimes) and dryland hairy vetch. Cover crops not listed within each year produced negligible yields.

Cover Crop Crude Protein:

There were no differences in crude protein among the cover crops in the first year. Hairy vetch had the greatest crude protein concentration in the second year.

Nodulation:

Tillage on the legume species studied (hairy vetch and burr medic) reduced the nodulation of the plant roots, thereby diminishing the amount of nitrogen that could be supplied to the cash crop.

Teff Yield:

In the first year, competition from rape-kale decreased teff cumulative yields compared to the other winter cover crops. Winter tillage reduced teff yields in the second year, regardless of winter irrigation or cover crop grown.

Soil Water Content:

The use of a winter cover crop did not significantly reduce the soil volumetric water content at any depth relative to the winter fallow. Tillage reduced the volumetric water content in the top two feet of soil in the tilled plots.

Final Outcomes:

Bee on a rape flower

Bee on a rape flower. Photo credit: Texas Tech University

A winter cover crop did not decrease soil water reserves more than a winter fallow. Switching to no-till reduced soil water loss and increased cumulative teff yields.

The results should help minimize producer concerns about water use by winter cover crops and the impact on the subsequent cash crop. For producers interested in growing a winter cover crop, the researchers recommend planting rye. Results showed that dryland rye produced a modest yield, even in a dry year. However, light irrigation is needed if producers intend to graze the crop during the winter.

For a more detailed analyses of the research results, visit the national SARE projects database and search by project number GS15-152.

Published by the Southern Region of the Sustainable Agriculture Research and Education (SARE) program. Funded by the USDA National Institute of Food and Agriculture (NIFA), Southern SARE operates under cooperative agreements with the University of Georgia, Fort Valley State University, and the Kerr Center for Sustainable Agriculture to offer competitive grants to advance sustainable agriculture in America's Southern region. This material is based upon work that is supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, through Southern Sustainable Agriculture Research and Education, under sub-award numbers: GS15-152. USDA is an equal opportunity employer and service provider. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.