Sugarcane residue decomposition by white and brown rot microorganisms

Harvesting green sugarcane with chopper harvesters results in up to 24 Mg/ha of post-harvest residue. Soil microorganisms can decompose residues and offer numerous ecological and economical benefits to growers; however, the process is dependent on the biotic density, diversity and activity in the soil. Further, the decomposition process is unfavourably slow such that sugar yields are adversely affected in emerging ratoons. The objective of this laboratory study is to investigate the effects on degradation rates when sugarcane residue is amended with a collection of indigenous soil microbes, C. urealyticum, C. cellulovorans, P. chyrsosporium and Cerioporiopsis sp., with or without a nutritive formulation. Loss in residue mass was monitored over a 9 wk period. Residues amended with microbes showed an 8.5% increase over the natural decomposition rate. Co-application of microbes with a basic nutritive formulation comprised of 27% humate, 19% carbon and 54% all-purpose flour resulted in a 15.8% increase in the natural decomposition rate. Enhancing this formulation with molasses or a nitrogen source, Eggstend® 300, showed no significant difference in decomposition rate when compared to the microbe only treatment. These laboratory findings suggest that sugarcane residues may decompose at accelerated rates when treated with microbes co-applied with specific nutritive formulations.