Analyzing soil-available phosphorus by the Mehlich-3 extraction method to recommend a phosphorus fertilizer application rate for maize production in northern Mozambique

The available phosphorus (P) in soil is a major limiting factor for maize productivity in the Nacala corridor, Mozambique. In this study, soils were collected from three representative sites, Ribaue, Nampula, and Nacala, in the area, and each was used for maize pot experiment with five P fertilizer levels. The soil-available P content was determined by the Mehlich-3 method at 30 days after P fertilization. The shoot biomass and P concentration at the tasseling stage increased as the P fertilizer level increased and were significantly expressed as a function of soil-available P. Based on the function, the available P that attains 90% of the maximum shoot biomass was estimated as 79 mg P₂O₅ kg⁻¹. Consequently, the results in this study suggest a recommendation of 32–74 kg P₂O₅ ha⁻¹ fertilizer for maize production in the Nacala corridor although a field evaluation and economical evaluation are necessary. Abbreviations: Ex-: exchangeable cations; M-3: Mehlich-3; T-N: total nitrogen; T-C: total carbon.