Integrating livestock and cropping systems: Interseeding cereal rye into corn for grazing

Interseeding annual forages into growing corn may be an alternative for both cover and grazing in temperate regions of the United States. A 4-year experiment evaluated the effect of interseeding cereal rye (Secale cereale) into corn for grazing after harvest on corn grain, forage biomass yield and quality, soil health, and estimated spatial biomass yields using vegetation indices (VIs) from multispectral imagery collected from an unmanned aircraft system platform. Corn was planted (79,074 plants ha^-1) each spring on two 4.8-ha sites in central Pennsylvania. Cereal rye was interseeded (135 kg ha^-1) into corn at the V4-V6 stage. Corn was harvested as grain in November, and each site was subdivided and randomly assigned to grazed or non-grazed treatments. Biomass yield and quality, soil samples, and estimates of biomass yield using VIs from multispectral imagery monitoring occurred in fall and spring. Results indicated that cereal rye plus corn stover provided enough forage for an additional 105-130 animal unit days ha^-1 with minimal impact on soil health indicators. Vegetative indices varied in the ability to predict biomass yield; all VIs except normalized difference red edge saturated at ∼2 Mg ha^-1. Spring growth of cereal rye was much less dependable than fall. Corn grain yields did not decrease (averaging 9.9 tonnes of dry matter ha^-1) as a result of grazing or due to continuous corn planting except in 2019 (dry year) when corn grain yields were reduced by 35%-40%. Interseeding cereal rye into corn that is harvested as grain can be a viable method to establish a cover crop to extend the grazing season without impairing cash crop yield.