The mineralizable N content reflects the amount of biologically active N in the soil [48], i.e., the N that can be progressively mineralized by microorganisms and thus made available to growing crops. The mineralizable N content increased significantly when fertilizer was applied, particularly PS45. This contrasts with the higher residual soil NO3 eN content in the N300 plots, which increases the risk of leaching. This combination of abundant mineralizable N but scarce mineral N suggests the N cycle is more tightly coupled to plant requirements in the PS45 plots, with concomitant positive effects on soil fertility and the environment. Similar results were reported in previous studies comparing organic and mineral fertilizers for maize production