Isabel M Lima1 and Paul M White Jr2
1USDA-ARS Southern Regional Research Center, Commodity Utilization Research Unit, 1100 Allen Toussaint Blvd, New Orleans, LA, 70124, USA; Isabel.Lima@usda.gov
2USDA-ARS, Sugarcane Research Unit, 5883 USDA Road, Houma, LA, 70360, USA
Surplus bagasse from sugarcane factories and leaf residue left in the field remain untapped resources associated with the harvesting and processing of sugarcane. By reutilizing and converting these by-products into profitable materials, the industry can move further towards sustainability. One such technology entails the thermo-chemical conversion of these by-products into biochars for agricultural and industrial uses. Biochar produced from field leaf residue (LB) and sugarcane bagasse (BB) were applied once at either 0.80 or 1.60 t/ha to sugarcane and crop performance was measured over 4 years from plant cane to third ratoon. Through their high content in organic matter, fixed carbon and H:C ratio (68.8%, 64%, 0.48 and 71.1%, 60%, 0.46 for BB and LB, respectively), both biochars contributed carbon to the soil, helped build soil organic carbon, and increased the permanent carbon pool in the soil. Additionally, all biochar treatments led to improvements in crop performance parameters, such as stalk weight, cane yield, total recoverable sucrose and sucrose yield. Best results were determined for field application of LB at 0.80 t/ha followed by BB at 1.6 t/ha, specifically with 0.90 and 0.88 kg per stalk, cane yield of 85.8 and 83.3 t/ha, sucrose yield of 8.65 and 8.21 t/ha, respectively, when compared to control (no biochar added) at 0.78 kg per stalk, cane yield of 68.3 t/ha and sucrose yield of 6.57 t/ha. Considering the cumulative sugar yield over four years, additional income can be realized from amending soil with biochar. Best outcome for this study resulted in estimated sugar profits up to additional US$6,837/ha for LB addition rates at 0.80 t/ha (raw sugar priced at US$0.82/kg).