- Agronomic: soybeans
- Crop Production: cover crops
- Education and Training: on-farm/ranch research
- Soil Management: organic matter, soil analysis, soil quality/health
Degrading soil health, biodiversity, and soil resilience are major challenges to sustainable crop production under changing climates (Freckman and Virginia, 1997). Excessive tillage, inappropriate crop rotations, monocultures, excessive grazing or crop residue removal have degraded soils in the Southern U.S. crop production systems. Recent extreme climatic events that drastically affected the South have exacerbated soil degradation in this region. Soil health is strongly related with beneficial soil and ecosystem functions including water storage, decomposition, and nutrient cycling; and responds sensitively to land management practices and climate. According to the Organic Farming Research Foundation survey among farmers (National Organic Research Agenda, 2016), 42 percent of respondents in the Southern US demanded more research to identify cultural practices to improve soil health that would improve the resilience of production systems to extreme weather. Recently, much attention is being focused on cover cropping as a sustainable practice to achieve these goals.
Reducing weed pressure on crops without affecting soil health through intense and frequent tillage and cultivation practices is a major challenge in sustainable crop production. With the increasing interest toward organic grain production in the Southern U.S., fall cover crops could be explored as a sustainable practice that reduce weed pressure, as well as improving soil health and cropping system intensity and diversity. Even though the multiple functions make cover crops a whole-farm system approach for improving sustainability and profitability of cropping systems, few producers in the South have included cover crops as part of their cropping systems. A major reason being lack of knowledge regarding the suitable cover crops for their locality that lead to improved use of resources and soil health. In addition, farmers often ask, "Why should I plant a cover crop that uses up all my water?"
To address this issue, we conducted a study (2016-2017 and 2017-2018 field seasons) to evaluate the common fall cover crops in South Carolina for water use with the financial support of the Southern SARE On-Farm Research Grant program. In this research, we evaluated seven cover crop treatments [rye, crimson clover, rye/crimson clover mixture, oat/ radish mixture, crimson clover/turnip mixture, Austrian winter peas/rye/wheat/crimson clover/hairy vetch mixture (Mixture of 5a), and oats/wheat/crimson clover/radish/turnip mixture (Mixture of 5b). Our results indicated that none of the cover crop treatments depleted soil water more than a fallow control.
In the present study, we determined the effect of the same cover crops on soil health and weed suppression, and their impact on the performance of the following cash crop. Our results indicated that mixture of 5a, rye, and the mixture of rye and crimson clover were the best cover crops in terms of biomass production and improving the following cash crop (soybean) performance. However, mixture of 5a was superior when soil health improvements were also considered.
Evaluate cover crops belonging to brassica, grass and legume groups, as individual species and in mixtures for their benefits to soil health and weed suppression.