Response of Sugarcane to Filter Press Mud and N, P, and K Fertilizers. I. Effect on Sugarcane Yield and Sucrose Content

Very little information is available regarding the plant nutrient value of filter press mud (FPM) for sugarcane. Yield increases of sugarcane as a result of FPM application have been inconsistent. Therefore eight field experiments were conducted to study the effect of FPM and NPK fertilizer, and their interaction on the yield and sucrose content of sugarcane (Saccharum officinarum L.). There were four plant cane and four ratoon experiments conducted over 2 years on seven sites. These included one experiment in which the residual effect of FPM after 1 year was studied. A split pl0t design was used with FPM on main plots (rates were 0, 20, and 40 metric tons/ha or 0 and 34 metric tons/ha dry wt with two or four replications), and N, P, and K fertilizer rates on subplots (two or four replications). The rates of fertilizers were as follows: N = 0, 94, and 188 kg/ha or 47, 94, and 141 kg/ha; P = 0, 45, and 90 kg/ha or 0 and 45 kg/ha; K = 0 and 112 kg/ha. Filter press mud increased the yield of cane in six experiments including the residual FPM experiment. Yield increases were higher in plant than in ratoon cane. Nitrogen increased the yield of cane in all experiments and in five experiments, rates higher than 94 kg N/ha, the standard practice, gave higher yield. The response of sugarcane to N-fertilizer was more related to the texture of the soil (r = −0.79) than N-content of the soil. Phosphorus increased the yield in seven experiments. Potassium gave a response in two out of five experiments. FPM✕P was the most interesting interaction and occurred in six experiments. This interaction reflected the inter-changeability of FPM at the rates studied with P.fertilizer. Other significant interactions were FPM✕N✕K, FPM✕N and N✕P. Filter press mud also improved the quality of the cane in four experiments while P-fertilizer improved it in three. On basis of these results, the following is recommended: 1) No P-fertilizer need be applied where FPM has been applied in quantities as high as 20 metric tons/ha dry wt basis, 2) ratoons following the plant cane may need P-fertilizer but possibly in much smaller amounts than normal, particularly if FPM rates are high, and 3) rates greater than 94 kg/ha are recommended particularly in the coarser textured soils.