Data and code from: Sowing date and seeding rate influence cereal rye productivity across the Northeastern United States

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.