A Survey of Biochars: Interactions with Dissolved Nitrogen and Phosphorous.

Research on biochar, a modern agricultural soil amendment with ancient roots, has revealed crop enhancement capabilities. Studies show biochar adds little to soil in the way of essential plant nutrients. Nevertheless, field experiments with poor soils such as in the Amazon Rain Forest and Australia show increased soil fertility after biochar amendments. A full explanation of the mechanism by which biochar increases soil-fertility may result in how biochar influences soil chemistry and soil processes. Prior published field and in-lab studies substantiate the hypothesis that biochar decreases nitrogen (N) leachate from soil, indicating a biochar-N interaction. Additionally, studies have shown biochar’s have unique phosphorous interactions too. Although studies have examined individual biochars N and P interactions, no study as of yet has systematically surveyed biochars from various production processes and parent materials. Results of biochar assessment studies may lead to a more complete understanding of the mechanism by which BC enhances soil quality. Our study examined the ammonia (NH4), nitrate (NO3), and Phosphate (PO4) sorption potentials of 30+ biochars produced from different production processes and parent materials. We performed both long and short term sorption experiments, where biochars were submerged in nutrient solutions.  Results indicate that, in general, biochars in the short term do not interact with NO3, however do decrease NH4 dissolved concentrations significantly and interact diversely with PO4.