Legume Biochar Fertilizer Can Be an Efficient Alternative to Compost in Integrated Nutrient Management of Paddy (Oryza sativa L.)

Continuous use of chemical fertilizers is detrimental to soil health and crop productivity. Therefore, we need to recycle the agroresidues in the valorized form (e.g., biochar or compost) to improve soil quality while maintaining crop yield. This study compares different nutrient management practices using varied dose combinations of biochar/compost for sustainable production of rice. We present the results from a controlled environment study under nine different nutrient management options to assess the effect of a novel legume biochar fertilizer compared with legume-derived compost. Our results suggest that a relatively smaller dose of soil test-based balanced fertilization (75% of required nutrients) added with novel biochar (25% nutrient equivalence) is the best combination in nutrient-poor vertisols of semi-arid tropics. The yield benefits from novel biochar fertilizer might find relevance to similar total–N content to compost, although there are noticeable differences in other macronutrients, secondary, and micronutrients. The surface area and C:N ratio are significantly higher for biochar (i.e., 4.47 m 2 g −1 ; 37.68) than that of compost (i.e., 0.87m 2 g −1 ; 10.5) which provides a boost to rhizospheric interactions resulting in higher plant nutrient uptake resulting in improved plant growth attributes at lower doses. In addition, integrated biochar with mineral fertilizers improves soil organic carbon at the harvest of paddy by 44–54% than sole mineral fertilizer compared to a meager increase (10–15%) in compost. This study suggests a novel alternative (as legume biochar fertilizer) to compost that can have policy implications for developing a carbon-negative fertilization technique in paddy farming.