Peat Characteristics and its Impact on Oil Palm Yield

Abstract The yield potential of oil palm planted on peat land has always been a controversial subject. Most past soil research on oil palm yield on peat land was mainly based on the depth and drainability. Little attention was given to the impact of peat characteristics on oil palm from a yield perspective. This study tests the hypothesis that physical soil properties such as peat maturity, presence of wood, depth and nature of underlying substratum affects oil palm yield. The initial study involved the evaluation of soil mapping units on estates in Sibu, Sarawak, East Malaysia and from this exercise of four organic soil mapping units which reflected the different characteristics of soils were selected. Data on peat depth, presence and absence of decomposed and undecomposed wood, nature of underlying substratum and peat maturity (fibric, sapric and hemic) were collected, analyzed and interpreted. Comparisons were also made on mineral soil found at the same location. Yield data were analyzed from primary sources from oil palm estates. Results show that different types of peat have significant effect on oil palm yield ranging between 9.47 - 22.92mt/ha. Peat maturity has the most significant effect on yield. Sapric peat showed a yield range of 19.48-22.92mt/ha as compared to hemic peat ranging between 9.47- 13.37mt/ha. Palms planted on soils with sandy substratum showed significant 18 -142% higher yields compared to those over marine clay as underlying material. No significant differences were observed in the yields due to the different depths and presence/absence of wood as a single factor. However, a combined factor of peat maturity and presence with nature of wood do have significant impact on yield. The study further confirms that sandy spodosol like Bako series perform 30 - 40.44% lower yields compared to peat soils such as Telong and Naman series. The results are important as peat areas with specific physical soil properties and showing poor yields can been left for conservation prior to development. Thus selective development based on semi detailed soil surveys producing maps giving peat characteristics and its impact to oil palm yield is possible. However, a more balanced view and future research should be emphasised to other issues such as cost of development of peatland compared to the price of crude palm oil in the world market, biodiversity, social issues, Green House Gas (GHG) emissions and potentials of improving productivity on existing organic and mineral soils need to be further explored. The study therefore challenges the existing believe that peat depth is very significant in determining oil palm yield. The study also enhances the need for soil surveys for land use decisions and wise use of peatlands. Further research is recommended to narrow the knowledge gaps and uncertainties on peatland. © 2014 Royal Netherlands Society for Agricultural Sciences.