Optimizing organic no‐till planted soybean with cover crop selection and termination timing

• Published in: Agronomy journal 2023-07, Vol.115 (4), p.1938-1956
• Main Authors: Liebert, Jeffrey, Mirsky, Steven B., Pelzer, Christopher J., Ryan, Matthew R.
• Format: Article
• Language: English
• ISSN: 0002-1962; 1435-0645
• DOI: 10.1002/agj2.21390

Research is needed to develop and optimize agroecological practices that can replace unsustainable managementand increase agricultural diversification. Field experiments were conducted in Maryland and New York to assess the effect of cover crop cultivar selection and cover crop termination soybean [Glycine max (L.) Merr.] planting (roll‐plant) date on cover crop growth stage, biomass, and reseeding; weed biomass; and soybean density and yield in organically managed no‐till planted soybean production. Twelve winter cereal cultivars—four each for barley (Hordeum vulgare L.), cereal rye (Secale cereale L.), and triticale (× Triticosecale Wittm. ex A. Camus.)—were seeded at equivalent densities and terminated at four roll‐plant dates. Although many cover crop cultivars had not yet reached the recommended growth stage for adequate termination (anthesis) at the earlier roll‐plant dates, greater soybean yields and similar cover crop reseeding, compared with later dates, were observed. Weed biomass was low across treatments despite cover crop biomass production below the recommended threshold of 8 Mg ha−1. When pooled over cultivars, triticale performed as well as cereal rye in terms of biomass production, weed suppression, and soybean yield. Within each species, differences in weed biomass and soybean yield were observed among cultivars, but inconsistent across site‐years. Results from this research also show that planting soybean before cover crop anthesis can help maximize yield. Farmers can improve management in cover crop‐based no‐till planted soybean by selecting regionally adapted winter cereal species and cultivars that perform well across a range of outcomes, rather than focusing exclusively on biomass production. Core ideas High cover crop biomass production and a narrow termination window are barriers in no‐till planted soybean. Pre‐anthesis termination can lead to adequate weed control, high crop yield, and minimal cover crop reseeding. Triticale performed better than barley and as well as—or better than—cereal rye at equivalent seeding density. Species and cultivar selection are important, yet undervalued, tools for optimizing no‐till planted soybean.