Wheat Straw Yield, Nutrient Uptake and Soil Chemical Changes in Two Coastal Plains Ultisols Amended with Uncharred and Pyrolyzed Sorghum Residues.

Current concerns about rising global population growth combined with global food security necessitate major optimization in agricultural management. The fertility of highly weathered Ultisols in the southeastern Coastal Plains region of United States is considerably low. In this region, intensive crop production depletes soil nutrients and reduces soil organic carbon. This will require replenishment of soil organic matter to sustain nutrient cycling and improve water- and nutrient-use efficiency. A potential solution is the use of raw or charred crop residues as soil amendments to enhance agricultural sustainability and crop productivity. Despite the recent interest in the use of biochar in agriculture, its current use is still limited. We hypothesized that sorghum (Sorghum bicolor, L) biochars (SB) would deliver more positive effects on winter wheat biomass and uptake than sorghum residues (SR). A greenhouse study was conducted to determine the contrasting effects of SB and SR with or without supplemental inorganic phosphorus (P) on biomass and nutrient uptake of winter wheat (Triticum aestivum, L) grown in Coastal Plains Ultisols. The application rate for SR and SB was 13 Mg/ha. Inorganic P was added at the rate of 40 kg P/ha. Overall, results of our study have supported our hypothesis. In highly weathered Coastal Plains Ultisols, addition of SB has provided several agronomic benefits and has no negative consequences in terms of wheat biomass and uptake. Results have shown greater efficacy of SB than SR on biomass productivity and nutrient uptake of winter wheat. Addition of SB increased total biomass of winter wheat by about 31% over the control plants. Yield and uptake responses of winter wheat and changes in soil properties have demonstrated the differing agronomic effects between uncharred and pyrolyzed sorghum residues. These results suggest that application of pyrolyzed sorghum residues will enhance productivity of plants and soil quality of Coastal Plains Ultisols.