Cover crop implementation strategies differentially impact in-field and downstream ecosystem service provisioning: A regional case study.

Cover cropping is an agricultural best management practice widely implemented as a strategy for reducing nutrient pollution. However, cover cropping impacts downstream ecosystems and in-field agricultural ecosystems in different and not necessarily beneficial ways. This study uses the Soil and Water Assessment Tool to examine downstream and in-field ecosystem services under multiple cover cropping scenarios, including current baseline conditions, increased cover crop implementation area, grain versus leguminous cover crop species, extended cover crop season length, and harvesting cover crop biomass as a hay crop. We quantified each scenario's impact on one downstream ecosystem service (water quality at the basin outlet) and five in-field ecosystem services (primary crop yield, hay yield, soil erosion regulation, soil organic matter, and nutrient cycling). Maximizing the area under cover crops increased primary crop yields by 5% and reduced downstream sediment loads by 25%, suggesting cover crops could theoretically achieve the Susquehanna River Basin's total maximum daily load goal for sediment reduction. However, without adjusted fertilizer application rates, increasing cover crop area drove increases in summertime nutrient loads at the basin outlet. Additional trade-offs occurred under the extended season scenario (primary crop yield vs. all other services) and the harvest scenario (hay yield vs. green manure effect). With careful management of these trade-offs, cover cropping has the potential to improve downstream water quality while reducing soil loss and promoting soil fertility on the agricultural lands where the practice is implemented.