Why breed legume cover crops
Although they offer many benefits, legume cover crops can be variable in performance. Management constraints and poorly performing germplasm are contributing factors. Unlike cash crops, cover crops have not been bred to optimize the traits that farmers need, particularly for specific regions of the United States. This deficiency means that modest investments in germplasm improvement could yield large benefits; thus we are taking advantage of this opportunity to improve legume cover crops through a multi-site project across the US.
The ideal legume cover crop provides valuable ecosystem services, such as nitrogen scavenging and fixation, reduced erosion, improved soil health, weed suppression, and the provision of habitat and resources for beneficial organisms such as pollinators. When optimized, cover crops can help address critical challenges to agricultural productivity, like adaptation to and mitigation against climate change, bolstering no-till agriculture in the face of multiple-herbicide resistant weeds, and minimizing nutrient loading in our water supply.
Cover Crop Survey
To help inform our breeding efforts, we conducted a national survey of organic and conventional farmers to learn about what cover crop traits they thought were important. The top four traits chosen by respondents were: nitrogen fixation, winter hardiness, biomass production, and early vigor.
Legume Selection Nurseries
Our legume cover crop breeding project is a multi-site project, with sites in Maryland, North Carolina, Minnesota, and here in New York. Our goal is to improve the germplasm of hairy vetch (Vicia villosa), Austrian winter pea (Pisum sativum), and crimson clover (Trifolium incarnatum) through traditional (non-GMO) and farmer-participatory methods.
In September of 2016 we hand-planted nurseries of hairy vetch and crimson clover, and used a cone-seeder to plant Austrian winter pea. We planted 27 accessions of hairy vetch (which meant handling 2,496 individual vetch seeds), 20 accessions of crimson clover, and 20 accessions of winter pea. We assessed the nurseries for winterkill, plant vigor, growth stage, biological nitrogen fixation, and early maturity. Before flowering, we selected the best individuals from the populations and culled the non-chosen plants. We are saving seeds from the chosen populations to replant in the second year of the trial.