Nutrient cycling and innovative approach of biomass management in oil palm plantation
The oil palm [Elaeis] industry is currently under pressure to develop production practices, which are agriculturally sustainable, economically viable, and environmentally sound, aftermath of the continuous increase in cost of production and unstable prices of the commodity. The maintenance and conservation of soil fertility constitute an important integral component of agricultural sustainability, which can be achieved through appropriate management of organic resources that are available in the ecosystem. Crop residues could replenish soil organic matter, build up soil nutrient reserves and increase crop productivity. This provides a sustainable method of maintaining fertility with an accompaniment of reduced inputs of organic fertilizers. A wide range of palm residues is usually available in the oil palm ecosystem. Pruned frond is one of the major sources of biomass produced from an oil palm plantation and is rich in plant nutrients and organic matter. It is estimated that 14.75 tonnes of pruned fronds (dry matter) are available annually from a hectare of oil palm. The total nutrient contents contributed from the pruned frond biomass are equivalent to 136 kg N, 10.3 kg P, 183 kg K, and 16.5 kg Mg per hectare per year. Studies have shown that removal of pruned fronds from a mature plantation adversely affects the growth performance of oil palms and soil nutrient contents. These adverse effects were reflected in yield response to fertilizer, nutrient uptake and soil fertility status. The adoption of zero burning in replanting oil palms could generate a significant source of organic matter and plant nutrients. The above ground biomass of the old palm stands contributed to about 85 tonnes of dry matter per hectare, with an additional 16 tonnes per hectare of below ground root biomass which contained a significant pool of nutrients and will be recycled in the plantation. The results of six-year study period in Malaysia showed that succeeding palms planted directly onto the residue piles that receive nutrients solely from recycling of palm residue inputs gave significantly higher yield as compared to the palms planted in the area with complete removal of oil palm biomass during replanting. The highest cumulative fresh fruit bunches yield of palms planted onto the residue piles over four-year period (25-72 months) registered at 71.5 tonnes per hectare, which was significantly higher than those planted in the bare plots without oil palm biomass which produced only 56.6 tonnes per hectare. Preliminary results of up to 30 months of the studies on the effects of different crop residue management with the application of different quantity of inorganic fertilizer inputs showed that the innovative technique of planting oil palm onto the residue piles during replanting gave similar results in terms of palm growth performance as compared with the palms that received half and full rate of normal estate fertilizer. The innovative technique could reduce the inputs of inorganic fertilizer. The young palms planted using the innovative technique could attain maturity much earlier than the palms planted following normal practice of replanting in between residue rows even though without inorganic fertilizer inputs. This paper will discuss on the management of oil palm biomass, which regulates nutrient cycling in an oil palm ecosystem, the processes and dynamics of soil organic matter, and nutrient management that could contribute to the development of a sustainable soil management system for the oil palm industry.