We conducted a two-year study to asses the feasibility of using locally available foliage materials, previously regarded as weeds, to improve soil fertility on smallholder farms in the Guinea savannah of Nigeria. We determined diversity and abundance of woody and non-woody species and monitored biomass production of identified species for more than two years. Tree populations on farmer's fields were estimated on twenty farms and their chemical characteristics were also determined. Qualities of foliage materials were determined using the Plant Residue Quality Index (PRQI). Soils under trees were analyzed for nutrient content. Twenty-eight tree species were identified at Yamrat, 15 of these were rated useful as green manure considering other local and economic uses. Tree-leaf biomass production ranged between 2.16 – 5.80 kg^-1 on a dry matter basis a few weeks after the rainy season began. Substantial quantities of recyclable plant nutrients; 1.23 – 2.39% N, 1.30 – 4.45% P, 12.7 – 66.3% K were observed. Other chemical characteristics ranged between 7.7 – 35% Lignin, 3.32 – 6.67% polyphenols, and 12.8 – 38.4 C/N ratio on a dry-matter basis. Organic carbon content of soils under the tree canopy ranged between 8.8 – 42.4g kg^-1. There was a significant negative relationship between the percentage N content of tree leaves and the organic carbon content of the soil under the tree canopy. Locally available foliage materials possess diverse chemical characteristics, which could be manipulated to improve soil fertility conditions of smallholder farm systems of the Nigerian Guinea savannah.