After three generations of oil palm planting: is there a need for sulphur and micronutrient fertilizers?

As the majority of Malaysian soils utilized for oil palm cultivation are low in nutrient status, optimal fertilization constitutes a key element for efficient production. Considerable research have been conducted on the mineral nutrition of the oil palm (Elaeis guineensis), involving both macronutrients and micronutrients. However, the potentially important nutrient sulphur (S), appears to have been overlooked, which is somewhat surprising for a large oil-bearing plant like oil palm. In quantitative terms, S ranks equally with phosphorus, if not higher. The apparent lack of interest in S thus far may be attributed to the widespread use of S-bearing fertilizers in the past, such as ammonium sulphate and kieserite. However, with increasing usage of higher nitrogen (N)-containing fertilizers, such as urea or cheaper N sources (ammonium chloride), and the use of locally produced dolomite as a magnesium source, it is possible that S deficiency may become a limiting factor in palm oil production in time to come. This could adversely affect the productivity of the oil palm. The results of a study of foliar sampling collected from a number of oil palm plantations at various locations in Peninsular and East Malaysia, covering both inland and coastal soil types, and analyzed for leaf Sand micronutrients content is presented. It was observed that nearly fifty percent of the foliar sampled from mature oil palms in Peninsular Malaysia are in the deficient or low S levels category. Sulphur deficiency levels in oil palm leaf were observed mostly in Peninsular Malaysia, whilst low levels are also found in the states of Sabah and Sarawak. In the case of micronutrients, current data indicate that they are still available in most soils, except for boron (B) on inland soils, and copper (Cu) and zinc (Zn) in peat soils. Most recent study also showed that manganese (Mn) and iron (Fe) content in most of the oil palm foliar samples are in the high range. The results indicates that annual B fertilizer applications are required for oil palm planted on inland soils, whilst Cu. Zn, and B fertilizers are required for oil palm particularly in the peat areas.