Yield Responses of Young Mature Oil Palms to NPK Fertiliser Application on Loamy Sand in Riau Province, Indonesia

摘要

In order to improve precision in fertiliser recommendations, a network of fertiliser trials were established on most of the major soil types found in AAG estates on Sumatera Island, Indonesia. Early findings from a 2 NPK factorial fertiliser trial established on loamy sand in Riau Province are reported here. The impoverished sandy soils of the trial sites were incapable of supporting high ffb production without fertiliser inputs. Without manuring, ffb yields averaged only 11.9 tonnes per hectare andpalm nutrient status declined rapidly in the following order: K>N>P. Correction of leaf nutrients to optimum levels by fertiliser application, was quickest with N, followed by P and K. Application of fertiliser resulted in a large and marked yield response (73%), increasing yields, on average by 8.7 tonnes per hectare per year over unfertilised plots. Inspite of the marginal nature of the soils, with correct agro-management practices, adequate rainfall and judicious fertiliser inputs, ffb yields in excess of 30 tonnes per hectare could be achieved and sustained. Maximum yields and profitability was obtained with an annual application of 11.5 kg fertiliser per palm (3.0 kg Urea, 3.0 kg RP, 4.5 kg MOP, 1.0 kg Kieserite).