Quantifying the productivity of selected soils in Nsukka and Abakaliki, Southeastern Nigeria using productivity index

A study quantifying the productivity of selected soils in Nsukka and Abakaliki areas of Southeastern Nigeria was carried out for two cropping seasons using modified productivity index model. The study involved two modifications of Pierce et al. (1983) productivity index model. Maize was used as test crop. The first involved the exclusion of sufficiencies for aeration and electrical conductivity (PIM1). The second entailed the inclusion of sufficiencies for organic carbon, available phosphorus and exchangeable aluminium with simultaneous exclusion of sufficiencies for aeration and electrical conductivity (P1M2). Results from the experiment showed a highly significant relationship (r 2 = 0.92 at P < 0.01) between P1M2 and maize grain yield. However, there was a poor relationship (r 2 = 0.41 at P<0.05) between P1M1 and grain yield. Similarly, the inclusion of sufficiencies for organic carbon and available phosphorus increased the validity of P1M2.