Integration of Perennials in Rowcrop Agriculture for Enhancing Water Quality in Central Iowa.

Many croplands planted to perennial grasses under the Conservation Reserve Program in the U.S. are being returned to crop production, particularly in response to the growing bioeconomy. The objective of this study was to quantify the impact of perennial filter strips (PFS) on sediment loss, and runoff as well as nitrate-nitrogen (NO₃-N) concentrations in surface runoff and shallow groundwater. The study, conducted in central Iowa, consisted of a balanced incomplete block design with 12 watersheds and four catchment-scale treatments having different proportions and topographic positions of PFS planted to a diverse native prairie mix. Non-perennial areas were maintained under a no-till two-year corn-soybean rotation since spring of 2007. Overall, the results indicated decreases in runoff, sediment, and nutrient loss from the watersheds with PFS compared to the watersheds with 100% cropland. Catchments receiving perennial treatments were similarly effective at reducing sediment loss. Similarly, total nitrogen and total phosphorus concentrations in runoff were reduced by similar magnitudes across all perennial treatments. The findings from this research are providing the information needed to design more integrated annual-perennial agroecosystems capable of providing multiple ecosystem services to society.