Intercropping in Summer Annual Forage Systems
Summer annual forage systems offer flexibility in their planting and harvest date and can act as “emergency forage” for livestock producers if corn or alfalfa fails. The goal of this work is to examine competition and inputs in various mixtures of four summer annual forage crops. By intercropping these forages together, we hope to optimize their productivity and forage quality by allowing resource partitioning. Increased diversity should also increase resource use efficiency and allow for reduced fertilizer inputs, herbicides, and seed use.
We hypothesize that mixtures will yield more than monocultures, and that mixtures of grasses and legumes will have comparable yields and weed suppression to grass monocultures, but higher forage quality. We also hypothesize that niche differentiation (sharing resources in a complementary way) will be greater for species with different nitrogen acquisition traits than for species with different statures.
We combined two species in eight different ratios to examine biculture performance; we also combined all four species in varying combinations to look at performance of more complex mixtures. Plantings were replicated in Aurora and Willsboro NY, and at the USDA Research Center in Beltsville MD.
Cover crops were planted with a no-till drill or cone-seeder in late June. Halfway through the growing season we measured the density of each species in the mixtures, as well as weed density and species in the plots. At the end of the growing season (90 days after planting), we sampled final biomass to determine dry matter of cover crop species and weeds.
Cover crop varieties used in mixes