Soil Erodibility, Phosphorous, and Microbial Biomass within a Switchgrass Stand

Abstract

Switchgrass (Panicum virgatum L.) is a native, warm season perennial that may be suitable for advanced renewable bioenergy feedstock production in semi-arid regions, where year-round soil cover is desirable as the primary environmental concern related to vegetation harvest is wind erosion. One objective of this project was to explore potential effects of two switchgrass varieties, Blackwell and Kanlow, on both abiotic and biotic soil quality indicators. No significant differences were detected in soil erodibility parameters, but numerically the cultivar with the lesser biomass and fewer plants per unit area had soil properties that had greater potential for wind erosion. Regardless of cultivar, soil P was enriched in the wind-erodible fraction compared with the bulk soil samples. Biological properties did not differ for the two switchgrass varieties, but microbial biomass and dehydrogenase enzyme activity was greater for samples collected <15 cm from the base of a plant than for samples >15 cm from the nearest switchgrass plant. No significant differences were detected between the two switchgrass varieties in this study, despite differences in the density of plants within the stand. Enrichment of soil P in the wind-erodible fraction and decreased microbial life in bare areas between plants highlight the importance of dense soil cover in a perennial switchgrass stand if it is to be considered as a feedstock for advanced bioenergy production.