Productivity of Maize (Zea mays L.) Varieties in Response to Integrated Coal and Inorganic Fertilizer Applications in Nigeria’s Sudan Savanna

This study investigated the effects of varying combinations of coal fertilizer (CF), NPK, and cow dung on the productivity of two maize varieties (SAMMAZ 27 and 29) across two Sudan Savanna locations in Nigeria, BUK and Dambatta, during the 2024 dry season. The experiment employed a split-plot design with variety occupying the main plot, and varied fertilizer combinations as subplots and replicated three times. Data were collected on vegetative growth, chlorophyll content, NDVI, reproductive development, and yield parameters. Significant (P < 0.001) differences were observed in the number of leaves per plant at 6 WAS, with 25% CF + 75% NPK, 50% CF + 50% NPK, and 100% NPK producing the highest values. Plant height and chlorophyll content were significantly greater in Dambatta at 8 WAS, while BUK supported superior early growth (stem girth and leaf number). Fertilizer effects were most pronounced at 6 and 8 WAS, with integrated treatments (25-50% CF + 50-75% NPK) consistently outperforming sole organic inputs. At 8 WAS, 50% CF + 50% NPK recorded the highest chlorophyll content (56.9 SPAD units). Stover yield was significantly (P < 0.001) influenced by fertilizer and location, with 100% NPK yielding the highest biomass at BUK (14,995.2 kg ha⁻¹). Grain yield showed no significant variation across treatments, although BUK recorded a higher overall yield (2,106.8 kg ha⁻¹). SAMMAZ 29 produced significantly more stover than SAMMAZ 27, while NDVI and stem girth responses varied by location and treatment. These findings show that combining CF with NPK enhances biomass production while maintaining grain yield. Integrated nutrient management should be promoted as a cost-effective, sustainable alternative to sole fertilizer use, offering farmers higher productivity and supporting soil fertility restoration in the Sudan Savanna.