The combined application of biochar and cow urine enhances organic rice production

Abstract

Abstract Enhancing the yield of rice (Oryza sativa) under organic farming conditions often presents difficulties due to nutrient deficits, particularly nitrogen, which restrict primary productivity. The application of organic amendments from various sources (e.g., nitrogen-abundant urine) is suggested as a method to boost crop productivity and soil fertility, and to rehabilitate degraded land. However, limited knowledge exists on the impact of cow urine combined with biochar-compost on local aromatic rice performance.In our study, we structured an experiment around two variables: a) three local aromatic rice varieties (Kalizera, Chinigura and Shhakharkhora), and b) five organic amendments (compost, cow urine, compost + cow urine, biochar-compost, and biochar-compost + cow urine). We measured plant performance and soil nutrient status to assess the impact. The results demonstrated that, on average, the Chinigura variety yielded a significantly higher grain output (3.13 t/ha) across all fertilizer treatments. Remarkably, the most considerable yield increase was observed with the combined use of compost and cow urine, reaching its peak with the biochar-compost + cow urine treatment (4.03 t/ha). This significant increase could be attributed to the cow-urine nitrogen retained on the surfaces of the biochar-compost, which subsequently improved the nitrogen availability to the plants. Supporting our initial hypothesis, we noted a substantial increase in soil and plant nitrogen (indicated by SPAD value) and grain absorption in the biochar-compost treatment. Our principal component analysis revealed positive relationships between grain yield and nutrient concentration in plants and soil. Our findings suggest that merging nitrogen-rich substances with compost could be a viable strategy for enhancing the yield of organically cultivated rice.