Soil nitrogen dynamics in switchgrass seeded to a marginal cropland in South Dakota

Abstract

The potential ecological impacts of switchgrass (Panicum virgatum L.), as a biofuel feedstock, have been assessed under different environmental conditions. However, limited information is available in understanding the integrated analysis of nitrogen (N) dynamics including soil nitrate ((Formula presented.)), nitrous oxide (N2O) emissions, and (Formula presented.) leaching under switchgrass land management. The specific objective was to explore N dynamics for 2009 through 2015 in switchgrass seeded to a marginally yielding cropland based on treatments of N fertilization rate (N rate; low, 0; medium, 56; high, 112 kg N ha−1) and landscape position (shoulder, backslope, and footslope). Our findings indicated that N rate impacted soil (Formula presented.) (0–5 cm depth) and surface N2O fluxes but did not impact (Formula presented.) leaching during the observed years. Medium N (56 kg N ha−1) was the optimal rate for increasing biomass yield with reduced environmental problems. Landscape position impacted the N dynamics. At the footslope position, soil (Formula presented.), soil (Formula presented.) leaching, and N2O fluxes were higher than the other landscape positions. Soil N2O fluxes and (Formula presented.) leaching had downward trends over the observed years. Growing switchgrass on marginally yielding croplands can store soil N, reduce N losses via leaching, and mitigate N2O emissions from soils to the atmosphere over the years. Switchgrass seeded on marginally yielding croplands can be beneficial in reducing N losses and can be grown as a sustainable bioenergy crop on these marginal lands.