Organic farming often faces the challenge of lower crop yields compared to conventional agriculture, primarily due to difficulties in supplying adequate amounts of nitrogen (N), a key nutrient for plant growth. This gap in productivity has long been a barrier to widespread adoption of sustainable farming practices, especially for major food crops like rice, which provides a significant portion of the dietary energy for people across Asia. A groundbreaking field study, published in the journal Scientific Reports by researchers Sharaban Tahura, Shamim Mia, Md. Harun Rashid, Md Kamal Hossain, Mohammad Mahmudur Rahman, and Keiji Jindo, offers a practical and powerful solution: a combined fertilizer of biochar-compost and cow urine. Their work demonstrates a highly effective, locally sourced method to overcome the nitrogen hurdle and significantly increase the productivity of specialty aromatic rice.

The research focused on three indigenous aromatic rice varieties—Kalizera, Chinigura, and Shhakharkhora—cultivated in Bangladesh. To test their hypothesis, the team applied various organic treatments, including compost alone, cow urine alone, and combinations of these, with the most important being the combination of biochar-compost and cow urine. The results were compelling: the highest grain yield, a robust 4.09 metric tons per hectare, was achieved by applying the biochar-compost and cow urine mixture to the Chinigura variety. This figure represents more than a 100% increase over the unamended control plots for the same rice variety, which yielded approximately 2.0 metric tons per hectare. This profound yield increment addresses the core issue of organic farming’s lower productivity.

The remarkable success of the combined treatment lies in its synergistic effect on nitrogen availability in the soil. Nitrogen is tricky to manage in organic systems because it is easily lost to the environment through processes like volatilization and leachingLeaching is the process where nutrients are dissolved and carried away from the soil by water. This can lead to nutrient depletion and environmental pollution. Biochar can help reduce leaching by improving nutrient retention in the soil.   More. The researchers found that the biochar-compost and cow urine mixture effectively managed this nutrient supply. The cow urine provided a source of readily available nitrogen, which the compost contained in a slower-release, mineralizable form. The addition of biochar—a carbon-rich, porous material—was critical; it possesses a high cation exchange capacity that allowed it to adsorb and retain the highly mobile nitrogen from the cow urine. This retention reduced nitrogen loss and allowed the plant to draw on the nutrient more efficiently over its growth cycle. At harvest, the plots treated with the biochar-compost and cow urine had the highest concentrations of soil ammonium and nitrate nitrogen, posting 44.92 mg/kg and 34.64 mg/kg respectively, an increase of 51% and 86% over the control soil.

This improved nutrient profile in the soil translated directly into enhanced plant health and productivity. The rice plants in the best-performing plots were taller and featured a higher number of effective tillers per hill, longer panicles, and more filled grains. The overall nitrogen status of the plants was confirmed by a leaf chlorophyll meter reading, which showed a strong positive correlation with final grain yield. More quantitatively, the nitrogen uptake into the grain was over 112% higher than in the control treatment, indicating that the plant was successfully utilizing the enriched nutrient pool created by the organic inputs.

In an era demanding both environmental sustainability and food security, these findings offer a pragmatic blueprint for future agricultural systems. By utilizing easily accessible, on-farm resources like cow urine and agricultural waste converted into biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More, farmers can dramatically boost the output of high-value crops like aromatic rice. The integration of readily available and slow-cycling nutrients, enhanced by biochar’s nutrient-holding capacity, not only improves crop yield but also contributes to soil health and reduced environmental degradation associated with synthetic fertilizers. This approach provides a practical, science-backed strategy for enhancing food security and profitability for smallholder farmers in climate-vulnerable regions.

Source: Tahura, S., Mia, S., Rashid, M. H., Hossain, M. K., Rahman, M. M., & Jindo, K. (2025). Combined application of biochar-compost and cow urine enhances organic rice production. Scientific Reports, 15, 39499.