Performance of oil palm on deep peat in relation to soil compaction and planting techniques

Severe leaning of palms is one of the major problems of oil palm planting on deep peat because they affect the palm growth and yield as well as pose difficulty in field operations. At MPOB Research Station Teluk Intan, Perak 94% of the palm planted on deep peat leaned, of which 29% were classified as mild and 65% as severe. Most of the leanings occured during the early mature period (3-5 years of planting) under mild category, whilst the palms leaned at the age more than six years were mostly under severe category. The effect of leaning on fresh fruits bunch (FFB) yield varied from 9 to 26% lower compared to the upright palms. The mild leaning palms had less FFB yield reduction, which was less than 9% compared to the severe category, which ranged from 15% to 26%. Besides leaning, termite infestation is another problem encountered on deep peat. At MPOB Research Station Sessang, Sarawak, an average of 8.4% termite infested palms was recorded over the 9 year planting period. Incidence or termite infestation at non-compacted area was slightly higher compared to compacted area due to poor in-field accessibility for effective control measures. The experience of planting oil palm on deep peat at MPOB Research Station Sessang, Sarawak indicated that soil compaction even with three rounds could not deter oil palms form leaning. Due to poor palm growth, the incidence of leaning in non-compacted area was lower compared to compacted area. The leaning incidence mostly occured during the early mature period, which subsequently gave advantage in terms of palm recovery. Over the six year period, the average FFB yield was significantly higher at the compacted area ranging from 19.2 to 20.2 t ha-1 yr-1 compared to non-compacted area was 50% lower compared to compacted area but improved from third year onwards. No significant improvement in FFB yield was recorded from increased rounds of soil compaction. Over the nine year planting period, almost 80% of the palms planted by slanting-hole technique were leaned, of which, more than 60% were under mild leaning category and 20% were under severe category. The slanting-hole planting technique gave a proper leaning direction, of which, more than 80% were unidirectional leaning and futher improved in compacted area. The FFB yield in the first two years of harvesting using slanting-hole planting technique was slightly lower compared to other planting technique but then improved from third year onwards. In later years, the slating-hole planting technique was expected to have higher FFB yield due to proper leaning direction and early palm recovery. The slanting-hole planting technique produced results that minimize leaning problems to a more manageable level. It is recommended that this planting technique be adopted for oil palm planting on deep peat.