Evaluating the Benefits of Vegetative Buffers Based on Nitrogen Recovery and Biomass Production on Marginal Cropland.

Nutrient retention and soil erosion control are key goals in sustainable agricultural landscapes. Vegetative buffers consisting of productive perennial species can not only benefit agroecosystems, but also supply food and fuel. In this study, we evaluated the effectiveness of different crop systems in reducing runoff and nitrogen losses on marginal areas of three practicing farms. Four crop systems consisting of bioenergy crops (‘Kanlow’ switchgrass (Panicum virgatum L.)), forage crops (‘Virginia wildrye’ (Elymus virginicus L.)), woody crops, and annual crop rotations with and without cover crops were compared in both polyculture and monoculture designs. A total of ten treatments were tested in three locations at Urbana, IL, St. Charles, IL, and Dixon Springs, IL in 2014 and 2015. Yield of bioenergy crops and corn/soybean rotations systems were evaluated in the second year of the long-term study. Leachate water samples were collected from all treatments using a lysimeter system in spring, summer, and fall growing seasons for nitrogen concentration analysis. Average annual forage biomass yield was 7.1 and 3.5 Mg ha^-1 in Urbana and Dixon Springs, respectively. The average annual bioenergy feedstock yield was 8.7 and 6.5 Mg ha^-1 in Urbana and Dixon Springs, respectively. Nitrogen concentrations in water varied across locations among forage, bioenergy, and woody crops. However, the nitrogen concentration levels in corn/soybean rotation system were 7 to 22 fold greater than in perennial crop systems (bioenergy, woody, or forage crops), except for St. Charles site where a flooding issue occurred in spring 2015. Our study demonstrated that a multi-functional buffer system can provide both environmental benefits and feedstock for Midwest region where corn/soybean cropping systems prevail.