Effects of residue management on nitrogen losses in surface and sub-surface water from sugarcane fields

The effect of three sugarcane (Saccharum officinarum L.) residue-management plans on nitrogen losses in surface runoff and sub-surface leachate was studied for 3 years. The three management plans evaluated were conventional burning (CB), compost application with burning (COMB), and remaining green cane trash blanketing (GCTB) treatment. In the CB treatment, sugarcane residue was burned after harvest. The COMB treatment consisted of compost applied at off bar' with sugarcane residue burned immediately after harvest. Compost was applied in the amount of 13.4 Mg ha(-1) annually. Surface runoff was collected with automatic refrigerated samplers and sub-surface leachate was collected with pan lysimeters over a period of 3 years. Total nitrogen (TN), NO3/NO2-N, and NH4-N were measured. The mean losses of nitrogen (TN, NO3/NO2-N, and NH4-N) from the COMB treatment after the burning procedure (post-harvest, years 2 and 3) were on average 2.7 times higher than those before harvest and burning (pre-harvest, year 1). Mean leaching losses of NO3/NO2-N were 0.36, 0.82, and 0.10kgha(-1) for the CB, COMB, and GCTB treatment, respectively. The losses of NO3/NO2-N from the GCTB treatment in surface runoff and sub-surface leachate were significantly reduced compared to the CB and COMB treatment.