Biochar effects on yield and nitrogen accumulation of hairy vetch（Vicia villosa Roth.) and crimson clover（Trifolium incarnatum L.).

Abstract

Among important strategies aiming to promote sustainable agriculture are soil amendments using biochar for enhancing legumes’ yield levels and biological nitrogen fixation (BNF) rates, while few study determined the optimum biochar application rates, which can depend on crop specific BNF strategies and nitrogen fixing bacteria. In this unirrigated unfertilized field study using pots, different biochar application rates (0, 30, 60 t/ha) were tested for each of two legume crops (hairy vetch: Vicia villosa and crimson clover: Trifolium incarnatum) having different BNF strategies and nitrogen fixing bacteria. We found the highest phosphorus uptake, potassium uptake, nitrogen accumulation, and yield levels for hairy vetch at biochar application rates of 60 t/ha, meaning that biochar application rates around 60 t/ha could maximize the yield levels and the incease of nitrogen contents (crop and soil) for hairy vetch. No measurements in this study for crimson clover were affected by biochar application. Further research is needed for determining the precise biochar application rates which can maximize yield levels and BNF rates for hairy vetch and crimson clover by using stable isotope ratio.