Maize Growth and Yield Response to Incremental Rates of Nitrogen in N-Depleted Lixisols in Northern Ghana

To help economize fertilizer use and predict soil-based and site-specific fertilization regimes in crop production, knowledge on crop response to incremental rates of nutrition have long been identified to play a significant role. In the nutrient-poor lixisols of northern Ghana where bulk of Ghanaian maize is produced, the response of maize growth and yield to eleven rates of N fertilization was evaluated in 2019 as a first step in developing a tool that could predict site-specific nitrogen rates for optimum maize production. The rates were 00, 15, 30, 45, 60, 75, 90, 105, 120, 135, and 150 kg/ha; laid out in a Randomized Complete Block Design. Collected maize growth and yield data were subjected to analyses of variance, where significantly different means were separated at a probability of 5% using the least significant difference. The study revealed no significant differences in plant height from the third to sixth week after planting, days to 50% flowering, 100 grain weight, and leaf area index at sixth week after planting. However, plant height and leaf area index at ninth week, cob weight, cob length, straw weight and grain yield were significantly affected by N fertilizer rates. Increasing nitrogen fertilizer rates had a pronounced effect on later-stages of growth, on grain yield and on yield components of maize. Application of 120 to 150 kg/ha N achieved statistically similar, and maximum growth and yield parameters compared to lower rates. The findings provide essential agronomic data required to relate soil test results with corresponding maize yield.