MAIZE GROWTH AND YIELD RESPONSE TO INCREMENTAL RATES OF PHOSPHORUS IN P-DEPLETED LIXISOLS OF NOTHERN GHANA

Abstract

It has long been postulated that the efficient use of phosphatic fertilizers must be based on information on inherent soil P-levels for the development of site-specific fertilization that must, in turn, be based on crop response to known nutrient levels. However knowledge remains relatively sparse on crop response to incremental rates of P2O5 fertilization on soils of known P levels to serve as proxy for development of site-specific P2O5 predicting tool that is required for optimum maize production. In the P-deficient Lixisols of northern Ghana, the effect of eleven rates of P2O5 fertilization were evaluated for growth and yield of maize. The P2O5 rates used were 00, 05, 10, 15, 20, 25, 30, 35, 40, 45, and 50 kg/ha; laid out in a Randomized Complete Block Design with four replicates. Data were collected on maize growth and yield and subjected to analyses of variance, where means were separated at a probability of 5% using the least significant difference. Results of the evaluation indicated significant effect of P2O5 rate on maize plant height, leaf area index, days to 50% flowering, cob weight, cob length, 100 seed weight, straw weight and grain yield. Increasing P2O5 rates had pronounced effect on growth, on grain yield and on yield components of maize. Application of 50 kg/ha resulted in maximum leaf area index (3.84), 100 seed weight (23.49 g), straw weight (9.3 t/ha) and grain yield (3.09 t/ha) as compared to the minimum values in the control treatments (1.57, 14.8 g, 3.3 t/ha and 0.71 t/ha respectively). The findings show that phosphorus fertilization is essential for maize growth and yield and serves as an entry point for relating soil test data with corresponding yield and the subsequent development of a fertilization tool that can help to predict site-specific P2O5 fertilization, based on soil test results.