Evaluating Corn Yield and Plant and Soil Nutrient Concentrations under Application of Synthetic Fertilizer and Dairy Manure

Manure application in field corn can sustain corn yields and reduce nutrient losses in the soil profile. A field trial was conducted to evaluate the impact of applying manure and synthetic fertilizer on nutrient concentrations in plants and soil, and on field corn yield. Experimental treatments included applications of synthetic fertilizer (NPK) and dairy manure at 5, 10, and 15 tons acre^-1 in addition to a non-fertilized control. All the manure was applied before planting, whereas synthetic fertilizer was applied in splits during the crop growth season. Corn was manually harvested, and plants were separated into leaves, stems, and cobs to determine dry weights. Post-harvest soil sampling was performed at 0-30, 30-60, and 60-90 cm soil depths. Results indicated that in-season leaf nutrient concentrations differed significantly among applied treatments. Application of synthetic fertilizer resulted in the highest plant height (116 in) and the highest corn yield (45.5 tons acre^-1) compared to the control and dairy manure application. Application of manure at 5 tons acre^-1 produced a higher corn yield (35.5 tons acre^-1) compared to manure application at 10 (25.9 tons acre^-1) and 15 tons acre^-1 (26.1 tons acre^-1). A similar trend was observed for the fresh and dry weights of leaves, stems, and cobs. Nutrient recovery was higher with synthetic fertilizer application, followed by manure at 5 tons acre^-1. Soil nutrient analysis indicated no significant differences in N, P, K, and S concentrations among treatments, except for NH₄⁺–N. However, nutrient concentrations across depths significantly differ. Results suggest that a combination of synthetic fertilizer application and manure might be a practical approach for balanced nutrient supply for field corn. Findings of this study establish a framework for improving manure-based nutrient management, with future work expanding its application across production systems.