Spatial Variability in Biomass Yield of Switchgrass, Native Prairie, and Corn at Field Scale

Abstract

Evaluating biofuel crop yield and its spatial variability on a field scale is important for determining the proper bioenergy crops suitable for specific lands. Within field spatial variability of switchgrass (Panicum virgatum L.), native prairie mix, and corn (Zea mays L.) biomass yield and its relation to soil properties were investigated in 2011 and 2012 at two farms in southwestern Michigan. At all sites and years, the order of biomass yields was corn > switchgrass > native prairie, which was consistent with fertilization rates of the crops. Short stand age of the perennial grass also contributed to the relatively lower yield. At both sites, switchgrass yield was not significantly different between 2011 and 2012, while corn yield was significantly lower in 2012 than in 2011. For switchgrass, within‐field variation was found considerably larger than the variation between years or between sites, while the variation between years or sites were comparable or greater than the within field variation for corn or native prairie. Two factors extracted from partial least square regressions (PLSRs) between biomass yield with soil and topographic variables could explain the majority of within field spatial variation for most of the fields in the study. Weight values of predictor variables from PLSRs were found strongly correlated between the 2 yr for a given crop at the same site with correlation coefficients from 0.65 to 0.89, as well as between switchgrass and native prairie at a given site.