Sugarcane bagasse and leaf residue biochars as soil amendment for increased sugar and cane yields

There are two potential untapped resources associated with the harvesting and processing of sugarcane, the trash (leaves and tops) left in the field and the sugarcane bagasse as surplus from the mills. Burning of sugarcane leaf residue in the field has been under scrutiny in recent years due to urban encroachment and air-quality concerns and excess leaf residue left in the field can also reduce ratoon crop yields due to lower soil temperatures and higher soil moisture. Sugarcane mills produce excess bagasse during the grinding season which is left unused indefinitely. These two organic feedstocks, sugarcane leaf residue and bagasse, can be thermo-chemically converted into biochars (BC) that can be brought back to the field to be used as a soil amendment to enhance soil health, water holding capacity and improve sugarcane yields. Biochars from sugarcane leaf residue (HoCP 96-540) and sugarcane bagasse were applied at three application rates, 0, 4 and 8%, with and without commercial fertilizer. Biochars and feedstock materials were chemically characterized for their nutrient content and several physico-chemical properties. Sugarcane biomass and theoretical recoverable sucrose (TRS) content were measured and compared across the different treatments. Best results were observed with a 4% addition of bagasse biochar with a TRS yield improvement of 22.3% and 31.6% from control, for fertilizer and no fertilizer additions, respectively. Benefits of applying biochar to cane fields include an increase in soil carbon content, improvement to soil drainage and aeration, and addition of nutrients for the sugarcane crop. Economic benefits are expected for both sugarcane growers and processors through the production of valued by-products from pyrolysis of sugarcane leaf residues and bagasse as well as enhancing the sugarcane industry's footprint in renewable energy markets.