Sowing date and seeding rate influence cereal rye productivity across the Northeastern United States

Authors: WELLMAN, LAUREL - Pennsylvania State University; Bagley, Gwendolyn; CRAWFORD, JAMIE - Cornell University; DARBY, HEATHER - University Of Vermont; DOONAN, NORA - University Of Connecticut; HASHEMI, MASOUD - University Of Massachusetts; HIRSH, SARAH - University Of Maryland; KREZINSKI, IVY - University Of Vermont; Mirsky, Steven; MOORE, VIRGINIA - Cornell University; SCOTT, BARBARA - University Of Delaware; SILLER, ARTIE - University Of Massachusetts; TAO, HAIYING - University Of Connecticut; VANGESSEL, MARK - University Of Delaware; VOLLMER, KURT - University Of Maryland; VOTYPKA, DAVE - Votypka Farms; WALLACE, JOHN - Pennsylvania State University

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/9/2026
Publication Date: 4/20/2026
Citation: Wellman, L., Bagley, G.A., Crawford, J., Darby, H., Doonan, N., Hashemi, M., Hirsh, S.M., Krezinski, I., Mirsky, S.B., Moore, V., Scott, B., Siller, A., Tao, H., Vangessel, M., Vollmer, K., Votypka, D., Wallace, J.M. 2026. Sowing date and seeding rate influence cereal rye productivity across the Northeastern United States. Agronomy Journal. 118(2). Article e70376. https://doi.org/10.1002/agj2.70376.
DOI: https://doi.org/10.1002/agj2.70376

Interpretive Summary: The more biomass a cereal rye cover crop produces and ground cover it provides, the more benefits (such as erosion control and nitrate leaching mitigation) it confers in the fields in which it is grown. The later a cereal rye cover crop is planted in the fall after cash crop harvest, the less biomass and ground cover it tends to provide. This study investigated whether increased cereal rye planting rates could make up for late planting in the Northeast US and if early spring ground cover could predict late spring biomass to guide the management decision making of farmers. The experiment was conducted across 13 site-years to test the effects of sowing date, relative to the historic first frost date of each location, and seeding rate (0, 17, 34, 67, 101,and 135 kg ha-1) on cereal rye biomass and ground cover and weed suppression. Delaying planting date from 2 weeks before to 2 weeks after the historic first frost date decreased cereal rye ground cover by 57% and biomass by 44%. Increasing seeding rates could not fully compensate for later planting. Increasing seeding rates up to 60 kg ha-1 maximized ground cover, biomass, and weed suppression at most site-years. Ground cover in early spring was correlated with biomass at cereal rye flowering, independent of planting date, indicating utility as a decision support indicator for growers. These results indicate that seeding rates up to 60 kg ha-1, lower than current existing regional recommendations, balance seed costs with potential benefits accrued in the Northeastern United States. Farmers and their advisors will use the results of this study to make better-informed decisions about cover crop planting rates and dates to promote the economic and environmental sustainability of US cropping systems.

Technical Abstract: Improving the management of cereal rye (Secale cereale L.), the most frequently used cover crop in the United States, provides an opportunity to enhance agroecosystem service provisioning. Services such as erosion control, weed suppression, and nitrate leaching mitigation are correlated with cereal rye ground cover and biomass, which decline as sowing dates are delayed. Our objective was to quantify whether increasing cereal rye seeding rates could compensate for lost growing degree days as sowing is delayed across the Northeastern United States, and if early spring ground cover could predict late spring biomass and guide grower decision making. We established a two-factor experiment across 13 site-years to test the effects of sowing date, relative to the historic first frost date of each location, and seeding rate (0, 17, 34, 67, 101, and 135 kg ha-1) on cereal rye productivity and weed suppression. Delaying sowing from 2 weeks before to 2 weeks after the historic first frost date decreased cereal rye ground cover by 57%, biomass by 44%. Increasing seeding rates could not fully compensate for fewer growing degree days. Increasing seeding rates up to 60 kg ha-1 maximized ground cover, biomass, and weed suppression at most site-years. Ground cover in early spring was correlated with biomass at anthesis, independent of sowing date, indicating utility as a decision support tool for growers. Overall, our results suggest that seeding rates up to 60 kg ha-1, which is lower than that existing regional recommendations, balance seed costs with ecosystem service provisioning potential in the Northeastern United States.