Combined application of biochar-compost and cow urine enhances organic rice production.

Boosting rice (Oryza sativa) yield under organic farming remains challenging, particularly due to nitrogen (N) limitations that hinder primary productivity. This study assessed the effects of cow urine combined with biochar-compost on the growth and yield of three indigenous aromatic rice cultivars (Kalizera, Chinigura, and Shhakharkhora). Five organic amendment treatments were tested: compost, cow urine, compost + cow urine, biochar-compost, and biochar-compost + cow urine. Chinigura showed the highest grain yield (3.13 t/ha), which increased significantly to 4.03 t/ha under the compost + cow urine treatment. The addition of cow urine to biochar-compost enhanced N availability in both soil and plant tissues. Principal component analysis (PCA) revealed strong positive correlations between grain yield and nutrient concentrations. These findings suggest that integrating N-rich organic inputs-particularly cow urine-with compost can improve the performance of local aromatic rice cultivars and enhance nutrient availability in organic systems.