This research project involves three field studies designed to assess the influence of selected tree species and inorganic inputs on carbon and nutrient accumulation and decomposition processes on degraded land. The first study is an evaluation of carbon and nutrient stocks in above-ground biomass in three 9-year old agroforestry systems established on abandoned pastures compared to naturally regenerating secondary forest. The agroforestry systems include a home garden, a palm-dominated system and a silvopastoral system. The second study is an evaluation of the combined use of legume trees and modest fertilizer inputs to boost the regeneration rate of a deforested, degraded Oxisol and ameliorate soil chemical properties. The one-year study included the trees: Inga edulis, Gliricidia sepium and Senna reticulata and inputs of P, lime and gypsum. The third study is an assessment of the rate of decomposition and nutrient release from litter generated by Inga edulis and Senna reticulata grown with P, lime and gypsum inputs.