Biochar Effects on Phosphorus Pools in Three Soils from Minnesota.

This greenhouse study was set up to assess the changes in the soil phosphorus (P) pools of three soils used for agricultural production in Minnesota as a result of biochar application and crop nutrient uptake. The soils included: excessively well-drained Hubbard loamy sand; poorly drained, calcareous Canisteo clay loam; and a well drained, Barnes loam. The amendments used included commercial fertilizer (triple superphosphate), gasification biochar (corn cob and stover), pyrolysis biochar (switchgrass), and combustion ash (turkey litter) and each amendment was tested at four rates based on the total P content of each material. The target P rates were 0, 56, 112, and 168 kg P ha^-1, which were applied to pot containing 1.5 kg of soil. The selected crops were wheat (Triticum aestivum) and corn (Zea mays) grown in a greenhouse for 8 weeks. Containers with soil and plants were kept between 60% to 80% of field capacity by weighing the pots on a regular basis and adding water as needed. At the beginning and at the end of the study, soil samples were collected and a modified Hedley fractionation procedure coupled with phosphatase hydrolysis was used to identify the P pools in the soils before and after the 8 weeks of incubation. Samples are currently being analyzed and results will be ready by the time the poster will be presented.