Fertilizer nitrogen rate effects on broiler litter–fertilized corn: Grain yield and nutrient composition

Abstract

Nitrogen (N) plays an important role in corn (Zea mays L.) production, but little is known of optimum fertilizer N rates for corn grain yield and nutrient composition when poultry manure such as broiler litter (BL) (Gallus gallus domesticus) is applied. Typically, farmers consider BL as a soil conditioner and often do not discount the N contribution from the BL application. Field experiments were conducted in 2020 and 2021 over three diverse environments across Alabama to determine the agronomic optimum nitrogen rate (AONR) for BL–fertilized dryland corn with five side dress fertilizer N rates (0, 84, 140, 196, and 252 kg N ha⁻¹). The study utilized a yield response curve and evaluated the effect of fertilizer N rate on grain nutrient composition. BL (4.48 Mg ha⁻¹ equivalent to 2-ton acre⁻¹) was applied to the study sites before planting each year. The AONRs for grain yield across these environments varied from 114 to 223 kg N ha⁻¹ (0.013–0.027 kg of fertilizer N per kg of grain yield ha⁻¹). The predicted grain yield at the AONRs ranged from 4.22 to 13.27 Mg ha⁻¹. Grain N concentration increased with increasing fertilizer N rate. However, the weak to nonexistent correlation between fertilizer N and other grain nutrient elements suggests that raising the fertilizer N rate does not necessarily lead to higher nutrient levels in corn grain. Overall, these findings could be useful for developing N management guidelines for corn fields that receive BL in Alabama.