Sugarcane Response to Phosphorus Fertilizer on Everglades Histosols

Determining sugarcane (Saccharum spp.) yield response to P fertilizer supports the development of agricultural best management practices consistent with Everglades restoration efforts. Field studies were conducted on organic soils to determine sugarcane yield responses to P fertilizer. Four test sites were established on Florida Histosols (water-extractable P = 1.3, 1.7, 2.1, and 9.0 g P m−3) with annual banded rates of 0, 9, 18, 36, 72, and 144 kg P ha−1 There were a total of 13 crop years with duration of each test ranging from 2 to 4 yr. Linear and quadratic regression and single degree of freedom contrasts were used to determine P fertilizer requirements. There were responses in t cane ha−1 (TCH) and t sucrose ha−1 (TSH) to P fertilizer application at four and three sites, respectively. Annual fertilizer P requirement at the four sites ranged from 18 to 33 kg P ha−1, with no consistent change in P requirement across crop years. Based on measured response (95% of maximum yield) in TCH and TSH up to 33 kg P ha−1, the maximum P recommendation for sugarcane grown on Florida Histosols should be maintained at 36 kg P ha−1 Minimal reductions in sucrose concentration (kg sucrose t−1 cane) were measured at P rates ≤36 kg P ha−1 Water-extractable P did not predict the measured yield response at all sites, demonstrating the need for an updated soil test calibration that should be applicable over a wide pH range and include both quickly available and reserve soil P.