Problem Soils: Managing Shallow Lateritic Soils
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Jitra
Shallow lateritic soils such as Malacca and Gajah Mati series, and their associated soils occupy 0.6 million hectares in Peninsular Malaysia (Law and Selvadurai, 1968). Early experiences indicated that oil palms grown on shallow lateritic soils came into bearing two years later and three times less compared to deep soils (Tan and Thong, 1975; Pang et al., 1977). Increasing the fertiliser rates only partially alleviate the constraint and improve yield by –% (Tan, 1973). Productivity also seems to improve with palm age (Tayeb et al., 1991).
These results show that the main problems with shallow lateritic soils are low effective soil volume, poor nutrient status and water holding capacity. These detriments further hinder root development, which aggravates oil palm growth and production. It has to be mentioned that the types and compactness of the laterites also play a major role on the degree of severity of limitations to oil palms. For example, the less compact and subangular laterites of Jitra series pose only moderate limitation to oil palms compared to very serious limitation in Malacca series despite both being shallow lateritic soils.
The main approaches to obtain satisfactory oil palms on shallow lateritic soils are to improve soil fertility and implement soil and water management adroitly. Improvement in soil fertility is necessary to increase nutrient uptake per unit soil volume. Since most lateritic soils are well weathered with low CEC and high P fixing capacity, it is necessary to maintain high and balanced rates of manuring as well as frequent applications to the palms. It is also essential to apply very large quantity of phosphate rocks to ensure sufficient P for good rooting activity.
The primary aims of soil and water management here are to reduce run-off and soil erosion, and build-up organic matter in the soil. These are achieved by:
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maintain desirable ground vegetation such as legumes during immaturity to early maturity phase and light grasses and Nephrolepis biserrata in later years,
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Spread the pruned fronds as broadly as possible. In flat areas, L-shaped frond stacking should be carried out while in terraced areas, they should be staked on the terraced lips and between the palms along the terraces,
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terraces must have sufficient back-slope and regular stops along the terraces to trap soil and water,
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mulching with empty fruit bunches (EFB) if available
Irrigation should only be conducted if it is economically viable, easy to maintain and a ready source of water during the dry season is available as mentioned in Part I of this lecture notes.
It is also advisable to increase the planting density to 148 palms ha-1 and extend ablation by 3 to 6 months for maximum leaf area index and high better yields.
Proper implementation of above soil fertility, and soil and water managements had raised the oil palm. Yields on commercial scale as shown in Figure 6.
