Switchgrass impact on selected soil parameters, including soil organic carbon, within six years of establishment

Switchgrass (Panicum virgatum L.) cultivation for bioenergy has the potential to improve soil properties. However, little is known about the changes in soil properties for first few years of switchgrass establishment. The objectives of this study were to evaluate the impacts of nitrogen fertilization rate (N rate) and landscape position on soil properties that include pH, soil organic carbon (SOC), total nitrogen (TN), soil bulk density (ρb), SOC stock, and phosphorus (P) for consecutive years (2009 through 2013) under switchgrass field in South Dakota. The experiment was a split-plot design with 4 replications of 3 N rates (low, 0 kg N ha−1; medium, 56 kg N ha−1; and high, 112 kg N ha−1) and 3 landscape positions (shoulder, backslope, and footslope). Data from this study showed that N rate did not impact the selected parameters at all five (0-5, 5-15, 15-30, 30-60, and 60-100 cm) depths from 2009 to 2013. The landscape position significantly influenced these properties for all five depths in 2009-2013. These properties showed some pattern among the three N rates and positions. The year significantly impacted these properties at some sampling depths. The SOC and TN at the 0- to 5-cm depth had an increasing trend over the observed years. These findings indicate that N rate cannot impact the soil properties, and footslope position can be beneficial for improving these soil properties. This study concludes that switchgrass can be a sustainable energy crop to improve or stabilize the soil properties over the years.