Soil carbon sequestration has emerged as an innovative approach that may offer an efficient way to global warming mitigation and improve soil fertility. Agricultural byproducts such as pecan shells (PC), peanut shells (PS), and cotton gin (CG) are very good precursors for biochar production that can be used to sequester carbon and enhance plant growth. The objectives of this study were to (a) produce biochars from different byproducts [PC, PS, CG, and switchgrass (Panicum virgatum L.)] at different pyrolysis temperatures and times, and determine their physico-chemical properties, (b) apply the biochars to the piedmont region soil (Mecklenburg soil) and determine their effects on the soil fertility characteristics such as water holding capacity, pH, CEC, and assess the leaching of nutrients from amended soil, (c) select the best biochars based on a set of the most important soil parameters for the plant growth using statistical models,(d) perform a greenhouse testing of the best biochars using lettuce as a crop, and (e) determine the effect of the best biochars on the greenhouse gases (GHGs) emission (CO₂) during a 10-week soil incubation study. Soil properties were significantly improved after biochar addition. No significant increase in the crop biomass was noted, while a net decrease in GHGs was observed following the biochar addition to soil. The complexity of possible interactions between crop, soil, and biochar may be very large, as was evident from the present experiment with only one crop and one soil. More importantly, no negative aspects were apparent in this trial.

Keywords:agricultural by-products; biochar; plant growth; greenhouse gas emission