Effects of the three common Philippine Cover Crops namely Calopogonium mucunoides, Centrosema pubescens and Pueraria javanica on soil nitrogen. The results of the texture, hydraulic conductivity and water holding capacity were not affected. Likewise, the result showed there was no significant effect on soil nitrogen. However the cover crops contributed significantly to the root nitrogen, nodule count and rhizobial population with the soil nitrogen showing high correlation coefficient. The estimates of the potential nitrogen contribution from the biomass revealed that Centrosema pubescens could supply 293.1kg.N/ha followed by Calopogonium mucunoides with 154.1kg.N/ha and Pueraria javanica with 152.2 kg.N/ha. Long term experiment of similar studies is recommended to achieve significant increase in soil nitrogen.