Fertilizer management in oil palms

The oil palm industry spends very large sums of money annually on fertilizers.Fertilizers from the major variable expenditure item in production costs and also determine largely the crop production levels.Considerable research on oil palm nutrient requirements and their responses has been carried out.A system to formulate fertilizer programmes and predict yield responses to N and K fertilizers has been drown up ( PORIM Fertilizer Recommendation System). This system is based on multiple regression analysis of N and K fertilizer responses to palm and site characteristics.The system is evaluated for some widely grown soils together with another systems for formulating annual fertilizer requirements of mature oil palm based on nutrient balance.The predictions for maximum and actual site yields were also evaluated.The results indicate the need for further improvements to the PORIM system for fertilizer recommendations and yield predictions.Detailed studies on the important parameters affecting nutrient requirement and yield response such as slope, rainfall, silt content and drainage are needed.The results could possibly be recombined to formulate another predictive model.The nutrient balance approach appeared to be less susceptible to severe nutrient imbalances over the medium term.High yield achievement will probably require much increased nutrient inputs.Further research is required to increase fertilizer efficiency and ensure that excessive fertilizer applications are avoided.This can be achieved through more precise yield predictions, fertilizer recommendations and better estimates of fertilizer efficiency and nutrient availability from the soil.Residual fertilizers from past applications and internal nutrient recycling within the palms need to be taken into account. More advanced research techniques including use of radioisotopes are required now.The results and efforts to draw up more precise fertilizer rates will help to reduce the problems with fertilizer application.Use of mechanised fertilizer spreaders where possible will be very important to overcome labour scarcity problems.If recommended practices on fertilizer applications are followed, risks of pollution of the environment from fertilizer applications in oil palm wil be minimal.