Biomass potential of drill interseeded cover crops in corn in Kentucky

Drill interseeding is an alternative method for establishing annual cover crops (CCs), but regional weather and management practices, including soil-residual herbicides, could impact its success. Split-plot field experiments in Princeton, KY, assessed establishment and biomass of drill-interseeded annual ryegrass [Lolium perenne ssp. multiflorum (Lam.) Husnot] and orchardgrass (Dactylis glomerata L.) following different soil-residual herbicide rates (subplot factor) in corn (Zea mays L.); these treatments (whole plot factor) were compared to cereal rye (Secale cereale L.) sown after corn harvest and a no CC control. The herbicide did not affect establishment of either interseeded species in either year. Orchardgrass plants survived both summers, but density before tillering was only 8 and 25% of initial density in 2016 and 2017, respectively. Biomass by corn harvest (3.3 and 26.4 g m^–2 in 2016 and 2017, respectively) was similar across all herbicide treatments. Most annual ryegrass plants died before corn harvest, possibly due to heat stress. Corn yield was not affected by interseeded orchardgrass, but corn was unacceptably weedy in 1 yr as grass weeds could not be controlled chemically after orchardgrass emergence. By the following spring, cereal rye planted after corn harvest produced more biomass (360 and 289 g m^–2 in 2016–2017 and 2017–2018, respectively) than interseeded orchardgrass (48 and 130 g m^–2 in 2016–2017 and 2017–2018, respectively). Orchardgrass was better suited to interseeding than annual ryegrass, but biomass was limited by low plant survival. Southern producers must weigh potential benefits of interseeding against those provided by cereal rye planted after harvest.