Response of young oil palms to combination of EFB compost and slow-release fertilizer (SRF) in loamy sand soil / Siraj Munir Mohammad

Oil palm (Elaeis guineensis) has become one of the largest contributors among the agriculture commodities towards the Malaysian economy and being the main source of income especially for the smallholders. In meeting the large demands of export from consumer countries, cultivation of oil palm has shifted even towards marginalized lands. Large amounts of fertilizers are being applied in oil palm cultivation in sandy coastal soil having high porosity to overcome the loss of nutrients from leaching. The objective of the study was to determine the effect of the combination of slow-release fertilizers (SRF) and empty fruit bunch (EFB) compost on the growth of two years’ old oil palm in coastal sandy soil. An experiment with Randomized Complete Block Design (RCBD) was conducted with five fertilizer treatments replicated four times over 18 months, from 28 May 2017 until 28 November 2018. The treatments were: T1 (100% NPK fertilizer), T2 (50% NPK + 50% SRF), T3 (100% SRF), T4 (50% NPK + EFB compost), and T5 (50% SRF + EF compost) of equivalent 100 g Nitrogen (N). The effect of the treatments on soil physical and chemical properties that included soil moisture, bulk density, soil texture, soil pH, soil total N, and soil available P were determined. The plant N and plant P content from Frond 9 and the growth of oil palm based on palm height, palm bole diameter and leaf area were also determined. The analysis did not indicate significant differences between treatments for soil physical properties. Similarly, soil chemical analysis of soil pH, soil total N and soil available P did not indicate significant differences between treatments. There were no significant differences obtained in the plant N and plant P content. For palm growth, steady growth was observed for all treatments although ANOVA indicated no significant differences. A significant positive but weak correlation of Pearson Correlation Coefficient of 0.698 between bole diameter and leaf area was obtained. There was also significant positive correlation between leaf N content and the bole diameter and leaf area with Pearson Correlation Coefficients of 0.359 and 0.520, respectively. The study concluded that despite reducing the amount of either NPK or SRF chemical fertilizer application to 50% and combining EFB compost supplying the balance of the 50% N, the palm growth is still able to be on par with 100% N from the chemical fertilizers. The recommendation of the combination of SRF and EFB compost was made due to the cost factor attributed by the higher frequency of NPK fertilizer application requiring four times per year as compared to SRF at two times thus reducing labour cost. The findings have showed that despite no significant difference was observed between treatments, cost analysis showed reduction in cost of input. This finding provides smallholders with an alternative method for fertilizer application.