The influence of post-harvest residue management on water quality and sugarcane yield in Louisiana
2009
Viator, Howard P. | Flanagan, James | Gaston, Lewis | Hall, Steven | Hoy, Jeffrey | Hymel, Thomas | Kennedy, Charles | Legendre, Benjamin | Wang, J.J. | Zhou, Marvellous
Louisiana sugarcane (Saccharum officinarum L.) growers are increasingly harvesting fields ‘green’, without pre-harvest burning to eliminate leafy material. The post-harvest residue, however, is generally burned on the ground to avoid the debilitating effects of the residue on the subsequent ratoon crop in the production cycle. A best management practice (BMP) that allows for the retention of the residue to minimize surface runoff and increase the soil fertility status would be viewed as both environmentally sound and producer friendly. The objectives of this study were to evaluate the effects of four post-harvest residue management treatments on surface water quality and sugarcane development and yield at two locations in the Vermilion-Teche watershed. Treatments included two approaches designed to mitigate the adverse effects of retained residue on sugarcane, the application of stabilized urea plus composted tea (generated from sugarcane bagasse, poultry litter and corn gluten) and the shredding of the residue for accelerated decomposition; and two treatments currently employed by the industry, ground burning of the residue and full post-harvest retention of the residue. “Edge-of-field” runoff collections were made using automated samplers. Rainfall collection-event load averages for all of the principal water quality parameters (total suspended and total dissolved solids, biological oxygen demand, nitrate and total phosphorus) for the four residue management treatments were not significantly different. Seasonal differences in soil erosion rates among the residue management treatments, however, indicated that exposed soil in the burned areas would be subject to higher sediment removal with high rainfall during the period from post-harvest burning to full-crop canopy. Neither of the residue management treatments designed to hasten residue decomposition was effective, with the urea-compost tea treatment producing elevated N levels in runoff and the shredded-residue treatment generating the greatest volume of surface runoff. The urea/compost tea and shredded-residue treatments were also ineffectual in either enhancing cane and sugar yield or promoting residue decomposition. Burning of the residue did not result in higher yields than retaining the residue.
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