This nationwide, farmer-participatory cover crop breeding (CCB) network focused on hairy vetch, crimson clover, and winter pea with the goal of releasing new, regionally adapted cultivars for organic systems. Breeding priorities include emergence, winter survival, fall and spring vigor, biomass, nitrogen (N) fixation; desirable flowering dates, disease resistance, seed yield, and absence of hard (dormant) seed and pod shattering (traits related to weediness). Scientists and farmers conducted field trials at multiple locations across the US to develop new breeding populations, evaluate promising advanced lines for cultivar development in different environments, and improve seed yields.

Vetch variety trials revealed genetic variation in seed dormancy and shattering, verified early (fall) indicators of spring vigor and high biomass, and identified promising new cultivars for commercial release. Crimson clover trials identified lines that combine high biomass and N with good fall emergence and winter survival. Strong genetic variation in winter pea cold-hardiness, disease resistance, biomass, and forage quality opens opportunities for developing improved cover crop varieties. Challenges with seed increase have arisen, leading to additional CCB trials to identify best locations, climates, and management practices for cover crop seed production.