Optimizing split-fertilizer applications for enhanced maize yield and nutrient use efficiency in Nigeria's Middle-belt

Inadequate and imbalanced fertilizer application is a significant barrier to achieving higher maize yields in Nigeria's Middle Belt. This study hypothesized that optimizing fertilizer types and application rates, particularly through split applications of straight fertilizers, can significantly enhance maize yield and nutrient use efficiency compared to conventional NPK blends and farmer's practices. This experiment evaluated the effects of optimizing types and amounts of fertilizer on maize growth and yield, soil characteristics, and nutrient use efficiencies in the mid-belt region of Nigeria. A field experiment was conducted at two locations using a randomized complete block design with four replications. The treatments included national and regional fertilizer recommendations, applied as NPK blends and straight fertilizers, along with a farmer's practice and control. Soil samples were collected before and after the experiment, and data on yield, yield attributes, grain, and leaf samples, were collected for analysis. The results showed that split applications of straight fertilizers increased grain yield by 22 %-46 %, achieving yields ranging from 2.37 to 3.08 t ha^-1, compared to yields from NPK blends. Nitrogen uptake efficiency improved by up to 52 %, while potassium uptake exceeded 100 % in certain treatments. Despite higher input costs, split applications yielded gross margins up to 35 % greater than those obtained with NPK blends, underscoring their economic viability. Split application of regional recommendation of 119:38:20 kg ha^-1 of N, P, and K from straight fertilizer shows higher yields and better nutrient efficiency than NPK blends, proving effective for optimum maize production in the region. No significant changes in soil physio-chemical properties, suggesting that long-term studies are needed to fully understand the impact of fertilizer practices on soil health<b>.</b> These findings strongly support the adoption of site-specific nutrient management strategies, particularly the use of straight fertilizers in split applications, to maximize maize production in Nigeria's Middle-Belt.