Best Management Practice for Crop Nutrition of Mature Oil Palm

There are substantial opportunities to increase yield and profitability on existing land through implementation of Best Management Practice (BMP) in oil palm estates. However, plantations are challenged with the identification and implementation of suitable BMP that would promise greatest financial gain. The IPNI Southeast Asia Program (IPNI SEAP, http://seap.ipni.net) has been instrumental in developing a BMP concept that has been successfully evaluated and introduced at larger scale in several estates. The gap between actual achieved yield (Y) in a plantation and the maximum yield potential (Y-max) can be apportioned into 3 parts: Yield Gap 1 arises from inefficiencies during development of a plantation until the end of the immature period; this limits the attainable yield (Y-a) in the mature stand compared to Y-max for a particular site; Yield Gap 2 (G2) arises from inaccurate assessment of nutrient requirements, which further reduces the attainable yield to the nutrient-limited yield (Y-n); and Yield Gap 3 (G3) arises from inefficiencies in the management of the mature stand, bringing Y-n down to the actual yield (Y). There are limited opportunities for plantations to correct Yield Gap 1 – the first during the initial establishment of the plantation, and thereafter at each occasion of replanting. However, Yield Gaps 2 and 3 can be corrected in existing mature stands. The yield gap analysis is useful for the identification, selection and prioritization of best management practices (BMPs) to be implemented for intensifying yield. IPNI SEAP aims at promoting BMP through collaborative projects in Southeast Asia providing assistance in training, agronomic and economic data analysis, and planning for wider scale implementation of BMP at a commercial scale. A series of six BMP projects established in 2006-2007 with 5 collaborating plantation groups in Indonesia focused on mature oil palms to determine the requirements for achieving maximum economic yield Y-mey. These projects addressed primarily the reduction of Yield Gap 3, with some efforts dedicated to reducing Yield Gap 2. Future expansion of oil palm globally is likely to be on degraded lands, often carrying small amounts of standing biomass. These lands often have low fertility status soils, possibly coupled with water deficits – potentially leading to a substantial Yield Gap 2. In Indonesia, such areas fall into marginally suitable (S3) or non-suitable (NS) classes under current crop suitability assessments. Maximum fruit bunch (FFB) yield on S3 areas is currently estimated at 30t/ha 12 years after planting – yet not often achieved on a sustainable basis. The concept of BMP has been demonstrated by IPNI SEAP to growers and seems relatively easy to accept at the commercial block scale. Yields before BMP implementation were relatively low at most demonstration sites. Ever since, yield has been and is still improving with BMP at most sites at commercially highly significant increments, and improved profitability has been demonstrated. IPNI SEAP has realized that the contribution to further increase yields, by explicitly addressing the reduction of Yield Gap 2, has not yet fully been understood and exploited and decided to take the concept further, by operationalizing a proof of concept of BMP for nutrient management. The results of this work will be specifically relevant for degraded low soil fertility environments. This project concept was subsequently developed and is now being implemented in Indonesia in one partner plantation.