Variable density plantings for oil palms (Elaeis guineensis) in Peninsular Malaysia.

The current planting density is a fixed option for the duration of the economic life cycle of the oil palms, which is about 25 years in Malaysia. As spacing requirements increase as palm grow bigger with age, the density giving greatest yield therefore decreases gradually from high to a lower stable density at some point in the planting cycle. This behavior is premise for one of the key options investigated in this project, the concept of variable density (VD). In this option, palms are planted at high densities and thinned when the starting density is no longer the optimum density for the given period. Because of the morphology of the oil palm, planting patterns influence greatly the yields obtained both before and after thinning. The project investigated several of the key elements in the variable density concept. These are starting and finishing densities, planting patterns, thinning periods, intensity of thinning and manuring requirements (one of the high cost items affected by density). A second option investigated is the concept of fixed high density plantings (HDP) on a shorter 18-20 year cycle. This allows a quicker introduction of newer varieties which are better yielding or with special traits (high IV, disease resistant, low height increment, etc.) in successive replants with concomitant better profitability. This option is also suitable for land under acquisition threat or development potential. The strategies are evaluated over 6 experiments on both coastal and inland soils. Results todate suggest both strategies are viable and have potential. Results from the spacing experiments indicate that HDP plantings on a shorter replanting cycle are more economical. However, on conventional planting cycles of 25 years, current fixed planting densities are still valid. The results from the variable density options suggest that initial starting densities at triangular spacing are better than other planting pattern despite the resultant spacing after thinning being asystematic. Starting densities at 180-200 palms per hectare at triangular spacing and thinned at around the 12th-14th year of planting by 14 25%, appears to be viable. Future research directions and experimental limitations are also discussed.