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

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.