Assessment of Phosphorus Availability and Maize Response in Acidic Soils of Imo State

Acid soil-induced phosphorus fixation is a major production constraint for maize farmers in the humid forest zone of South East Nigeria, and assessing liming combined with phosphorus fertiliser application as an amelioration strategy is important for improving maize productivity in Imo State. This study assessed the effect of lime application (0 and 2 tonnes per hectare) combined with three phosphorus fertiliser rates (0, 30, and 60 kg P2O5 ha-1) on soil pH, phosphorus availability, and maize yield at Owerri North LGA, Imo State, South East Nigeria. A 2x3 factorial experiment arranged in a randomised complete block design with three replications was conducted during the 2023 rainy season using SAMMAZ 15 variety. Soil pH, Bray-1 available phosphorus, plant uptake phosphorus, and grain yield were measured. Results showed that lime application significantly raised soil pH from 4.8 to 6.2 and increased available phosphorus by 48.3 percent compared to unlimed plots receiving equivalent phosphorus fertiliser. Lime combined with 60 kg P2O5 ha-1 produced the highest grain yield (4.14 tonnes per hectare), significantly greater than the control (1.87 t ha-1) and the no-lime high phosphorus treatment (3.02 t ha-1). The study concludes that lime application is a prerequisite for effective phosphorus fertiliser utilisation in Imo State acid soils and recommends the co-promotion of lime and phosphorus fertiliser through Imo State ADP input supply channels.

Keywords: acid soils, phosphorus fixation, lime application, maize yield, Imo State