The decomposition patterns of the oil palm residues were found to show a decreasing remaining of dry matter in the order: leaflets > rachises = trunks > roots. The leaflets reached t₅₀ at sir months, the rachises and trunks at eight months and the roots at 10 months. The decomposition rate constant ‘k’of the oil palm residues ranged from 0.13% to 0.22% day-¹ in which the leaflets, rachises, trunks and roots had a value of 0.22%, 0.17%, 0.17% and 0.13% day-¹ respectively. The controls regulating decomposition of oil palm residues during the study period have been shown to operate in the rank order: macroclimate > microclimate > resource quality > organisms. Rainfall distribution was the main climatic factor that controlled the moisture content of residual materials and the microclimate within different locations in the residue piles strongly modified the variation in temperature and moisture that affected the rate of decomposition. On the average, most of the oil palm residues were found to decompose within 12-18 months while some of the hardier materials, particularly roots, took much longer than 18 months to decompose. Significant accumulation of light organic carbon fraction on the soil surface will provide and relase nutrients to the soil. Nutrients released from oil palm residues showed different release patterns between residue types and nutrients. The leaflets, rachises, trunks and roots all showed nutrient release in the order: K>Mg=Ca>P>N. The release of nutrients from the residues was relatively quick, especially K, with more than 70% of the nutrients released. Generally, the release and transfer of nutrient to the soil pool occurred within the 18 months period.