Sugarcane residue and bagasse as biochar precursors for soil amendment applications

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 trash in the field has been under scrutiny in recent years due to urban encroachment and air-quality concerns and excess trash 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 for the remainder of the year.  These two organic feedstocks 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 feedstocks were chemically characterized for their nutrient content as well as several physico-chemical properties.  Sugarcane biomass and theoretical recoverable sucrose (TRS) content were measured and compared across the different treatments.  Possible benefits of biochar include an increase in soil carbon content, improvement of soil drainage and aeration, and addition of nutrients to the growing sugarcane crop.  Benefits are expected to both sugarcane growers and processors through the production of valued by-products from pyrolysis of sugarcane trash and bagasse as well as enhancing the sugarcane industry’s role in renewable energy markets.