Impacts of Biochar and Various Bioenergy Cropping Systems on Plant Available Soil Nutrients.

Laboratory and greenhouse studies have shown that biochar can impact nutrient availability and leaching, but there are few studies reporting the impact of biochar amendments on soil nutrient dynamics under field conditions for different bioenergy cropping systems. Here we investigated continuous no-till corn (CC), switchgrass (SG), high-diversity prairie (HD), and low diversity prairie (LD) cropping systems (perennials seeded spring 2012) in 16 large plots (0.35 Ha each). We hypothesize that biochar amendments will impact availability of nitrogen and other soil nutrients and will influence cropping system-soil nutrient interactions. The study is a split-plot design with application of 10 Mg/Ha of a mixed wood gasification biochar in fall 2011 on half of the 32 split plots. Remaining plots did not receive biochar. Soil samples were collected every year after harvest and analyzed for pH and Mehlich III extractable nutrients. Plant biomass of different cropping systems were collected and analyzed for nutrient uptake. Soil samples collected in 2014 and 2015 were analyzed for 2 M KCl extractable NO₃^- and NH₄⁺ and potentially mineralizable nitrogen. Cropping system, depth, and year all significantly affected soil N, P, and, K availability, however no consistent effects of biochar on soil nutrients was observed.