Evaluating the Effect of different Biochar Rates with Broiler Litter and Commercial Fertilizer on Greenhouse Gas Emissions, Soil Nutrient Dynamics and Cotton Lint Yield

Abstract

Biochar has gained attention as a promising agronomic tool to increase soil nutrient availability and crop productivity. However, efficacy of biochar application in combination with broiler litter (BL) and inorganic N fertilizer on soil nutrient dynamics and cotton lint yield is not well documented in Southeastern (SE) U.S. A two-year field study was conducted in coastal plain soils to evaluate the effect of four BC application rates (0, 4.5, 9, 18 Mg ha⁻¹) co-applied with either nitrogen (N) fertilizer urea (62 kg N ha⁻¹) or BL (44 and 60 kg N ha⁻¹ in 2024 and 2025, respectively) across nine treatments. Broiler litter (BL) was applied at a rate representative of regional farmer practices (4.5 Mg ha⁻¹). Based on the assumption that 50% of total N in BL is plant‑available, BL application rates were calibrated to deliver plant‑available N equivalent to the inorganic fertilizer. Urea was applied in two equal splits (31 kg N ha⁻¹ each), with the first application occurring one week before planting and the second at the cotton first square growth stage. Biochar was incorporated before experiment establishment in 2024, while fertilizer and BL were applied annually. The co application of biochar with BL or inorganic fertilizer did not result in a significant effect on greenhouse gas (GHG) emissions, soil nutrient availability, and cotton lint yield compared with broiler litter or fertilizer applied alone application without biochar. The interaction effect between biochar rates and N source on these parameters was also not found to be significant. However, N source significantly affected GHG emissions, soil nutrient availability and cotton lint yield at all biochar application rates with BL based treatments showed significantly higher GHG emissions, soil nutrient availability and lint yield compared to fertilizer based treated plots across both cotton growing seasons. These results suggest that in the short‑term, biochar application did not mitigate GHG emissions and had no significant effect on soil nutrient dynamics or lint yield under the conditions of this study, highlighting the need for long-term evaluation across different soil types and environmental conditions to understand the potential of biochar in sustainable cotton production systems.