The success of planting cover crops depends on choosing not only the appropriate species but also the appropriate planting and termination dates for addressing resource concerns.  In response to questions from NRCS field staff and producers, the Jamie L. Whitten Plant Materials Center in Coffeeville, MS, implemented a two-year study to evaluate planting windows for cool season annual legume cover crops in the Mid-South. Annual cool season legume cover crops can provide many benefits to production agriculture systems such as soil erosion control, reduced fertilizer costs, and improved yield. Two common cool season legume species utilized in the Mid-South are crimson clover (Trifolium incarnatum) and hairy vetch (Vicia villosa); however, establishing a cover crop within the proper window is critical to maximizing the benefits provided. 

In this study, monocultures of ‘Dixie’ crimson clover and ‘Purple Bounty’ hairy vetch were planted with a seed drill at 15 lbs/acre. Treatments consisted of five planting dates (September 15 to November 15) in combination with five termination dates (March 1 to May 1). At each termination date, samples were taken to determine dry matter yield and nitrogen concentrations in the aboveground biomass. Both species produced significantly greater dry matter and nitrogen production when planted from September 15 to October 15 and terminated on or after April 15. Legumes planted in November or terminated prior to April 15 tend to be riskier due to colder temperatures resulting in less plant growth. It is recommended that annual cool season legumes be planted between September 15 and October 15 and termination be delayed until April 15 to maximize dry matter production and nitrogen production in the Mid-South. For a more in depth look at this study, please see the following link: Planting and Termination Date Effect on Aboveground Performance of Two Cool Season Legume Cover Crops (usda.gov). 

With this and other work, the Plant Materials Program aims to share plant solutions that solve local and national conservation problems. For additional information on specific species of plants mentioned, please see the USDA PLANTS database. Technical information and guidance on the use of conservation plants to address resource concerns can be found on the Plant Materials Program website or  contact the nearest Plant Materials Center or plant materials specialist.