Managing Both Agronomic and Environmental Objectives with Grass:Legume Cover Crop Mixtures.

Cover crops are nonmarket crops that are used as multi-functional tools to provide agro-ecosystem services (e.g. erosion control, soil fertility, pest suppression, water infiltration and retention, increased soil carbon sequestration and reduced surface water pollution). Furthermore, cover crops can play an important role in the design of cropping systems that adapt to and mitigate against climate change. Given that farmers often seek a variety of benefits from cover crops, multi-species mixtures are a strategy that can be used to promote multiple functions simultaneously. However, cover crops are biological tools that respond to their environment, therefore the extent to which a cover crop provides a specific function depends not only the species selected, but also on their management and site conditions (management history, soils and climate). A suite of agronomic and environmental criteria were evaluated in field experiments conducted at the USDA Beltsville Agricultural Research Center in Beltsville, Maryland where a gradient of grass:legume cover crop mixture proportions were crossed with tillage (till vs. no-till) and fertility management regimes (rate, date, and type of fertility). The experiment provides a useful framework for evaluating the role of cover crop mixtures in maximizing multiple agro-ecosystem services.