Author : Soedarmadi Hardjosuwignjo

Summary : A field experiment was conducted at the Central Experiment Station, University of the Philippines at Los Banos, to characterize and to differentiate the effect of time of ipil-ipil leaves fertilization on some soil properties and the yield of IR-36 rice variety grown under non-flooded condition. Ten tons of fresh ipil-ipil leaves and 80-30-30 of N, P (subscript 2) O(subscript5), K (subscript2)O, (inorganic fertilizer), respectively, were the levels of fertilizer used in this experiment. Unfertilized plots served as the control. Application of ipil-ipil leaves 25 days before rice seedling significantly reduced bulk density of the soil as compared to the unfertilized and other ipil-ipil treatments. Soil water stable aggregate, however, was not significantly affected by any of the fertilizer treatments. Organic matter content, cation exchange capacity (CEC), available phosphorus and exchangeable potassium in the soil at maximum tillering stage of the plant significantly increased with the addition of ipil-ipil leaves either singly during seedling or split (1/2 at seeding and 1/2 25 days after seeding). Bacteria and actinomycetes population in the soil (taken at rice harvest period) also increased with split application of ipil-ipil leaves 1/2 at seeding and 1/2 25 days after seeding), as compared to the control. Grain yield of the rice plants fertilized with ipil-ipil leaves at 25 days before seeding was comparable to that fertilized with inorganic NPK.