COMPARATIVE ANALYSIS OF CONVENTIONAL VS REDUCED NPK FERTILIZATION ON MAIZE PERFORMANCE: A FOCUS ON BRIQUETTED UREA TOPDRESSING, SULPHUR, ZINC and BORON.

Abstract

Ghana's soils, particularly in the Guinea savannah ecological zone, experience a decline in fertility and productivity caused by nutrient depletion and leaching. Additionally, the excessive focus on primary nutrients (NPK) has pushed secondary and micronutrients into the background, resulting in farmers not achieving the maximum yield from their cultivated crops. The aim of the study was to assess if the incorporation of micronutrients (Zn and B) into a reduced NPK application rate (70 50-50) kg/ha could effectively substitute the standard recommended NPK rate of 90 60-60 kg/ha. The study also seeks to compare briquette urea with the traditional granular form of urea at top dressing. A total of seven fertilizer treatments were evaluated. The trial was laid out in a split plot design with top dressing assigned to the main plot and fertilizer rates assigned to the subplots. The results revealed that there was no significant difference in the use of granular or briquette urea for top dressing (P > 0.05). The recommended NPK rate generally improved plant height, leaf area index and leaf chlorophyll content compared to the reduced NPK rate. In terms of grain yield, the reduced NPK rate was not significantly different from the sole application of the recommended NPK rate (P > 0.05). The inclusion of Sulphur compensated for reduction of NPK rate only in cob length while the inclusion of micronutrients improved cob length, biomass and days to 50 % flowering. Although the Agronomic Efficiency of nitrogen applied was similar for the reduced and recommended NPK rates, the inclusion of S to the recommended rate contributed to a higher efficiency of nitrogen usage. The study has demonstrated that the inclusion of S to the recommended rate improves grain yield and agronomic efficiency of nitrogen. It is therefore recommended that NPK should be fortified with Sulphur. There is also the need for further work on partial budget analysis to determine the inclusion of the trace elements in fertilizer formulation.