Nitrogen and Phosphorus Released from Coconut Husk during Retting Treatment

抄録

Upland fields in Bohol of the Philippines are mostly located on areas with high slopes resulting in soil erosion. Although coconut husk has been applied as buffer strips for eliminating soil erosion, attention has been paid to the loss of nitrogen and phosphorus components not only discharged from synthetic fertilizer applied in upland fields but also those released from coconut husk. The leached nutrients associated with surface runoff and percolation water may cause pollution downstream. Thus, efficient utilization of the nutrient components from coconut husk is necessary from a view point of conservation agriculture in Bohol, Philippines. This study sought to find out the amounts of nitrogen and phosphorus in coconut husk, to quantify the amounts of nitrogen and phosphorus released from coconut husk during the pretreatment by retting process and to observe the optimum period of releasing nutrients from coconut husk. Retting of coconut husk were carried out for 140 days and small amounts of ret liquor was sampled at certain days of interval for nitrogen and phosphorus analyses. Based on the experimental results, it was observed that releasing nutrients from coconut husk rapidly increased from the starting day up to ten days of retting. Even after ten days, nutrient components released from coconut husk tended to increase gradually. It was also proven that about 87% of its phosphorus and 10% of its total nitrogen was released from the coconut husk. Therefore, it was concluded that coconut husk has a high tendency to release nutrients during the retting process, particularly for phosphorus component that can be a source for bio-fertilizer.