Tuesday, November 14, 2006

Post-Harvest Sugarcane Residue Management Strategies Studied Under Rainfall Simulator for Reduced Soil Erosion and Loss of Agrochemicals.

Carol Bronick, L.M. Southwick, and J.L Fouss. Agricultural Research Service, Soil and Water Research Unit, 4115 Gourrier Ave., Baton Rouge, LA 70808

Retaining some post-harvest sugarcane residue in the field has been shown to reduce runoff, erosion and off-site transport of agrochemicals; however the optimum level of residue retention needs to be evaluated in light of planned bio-energy plants utilizing sugarcane for ethanol production. Greenhouse rainfall simulations on Commerce silt loam in soil beds (0.6m x 1.5m) prepared to represent typical sugarcane management practices were used to assess the effects of residue management on runoff, sediments and agrochemical losses. Fertilizer (220 kg/ha applied as 32% N solution), atrazine and pendimethalin were applied. Runoff and sediments were collected and analyzed for pesticides and nutrients. A study of three residue management practices included full coverage, residue swept into center furrows and no residue (to simulate residue burning). Bare soil had the highest off-site transport (199 mm runoff, erosion of 1.9 Mg/ha, and nitrate loss of 9.0 kg/ha), full residue cover reduced runoff by 85 %, erosion by 95 %, and nitrate loss by 90 % and swept residue reduced runoff by 6 %, erosion by 60 % and nitrate loss by 32 %. Decreasing the amount of swept residue resulted in increased runoff, sediment, nutrient and pesticide losses. Another study included varying levels of swept residue (100%, 20% and 0%) indicated that higher levels of residue retention are necessary to limit soil and agrochemical loss by erosion. These results suggest that a higher residue cover will reduce off-site transport of agrochemicals and erosion with acceptable levels of bio-mass harvest for bio-energy production.

Handout (.ppt format, 6616.0 kb)