Nitrogen fertilizer is essential for modern agriculture, but a substantial share of applied nitrogen can escape from farmland rather than reaching crops.
One major pathway is ammonia volatilization, which wastes valuable fertilizer and contributes to air pollution and broader environmental problems.
Researchers in China have now found that adding both biochar and dicyandiamide to organic fertilizer could provide a more effective way to keep nitrogen in the agricultural system. In a two-year rice and wheat rotation experiment, the combined fertilizer reduced cumulative ammonia losses by 27.1 per cent compared with conventional urea fertilization, while maintaining crop productivity despite a 30 per cent reduction in mineral nitrogen input.
“Reducing fertilizer input is only useful if farmers can maintain crop production at the same time,” said corresponding author Haijun Sun. “Our results suggest that combining biochar with dicyandiamide in organic fertilizer can help balance these goals by retaining nitrogen, limiting ammonia losses, and supporting crop growth.”
The researchers conducted a greenhouse soil-column experiment covering two complete rice and wheat rotations from 2022 to 2024. They compared conventional urea fertilization with three treatments that used less mineral nitrogen: conventional organic fertilizer, biochar-amended organic fertilizer, and organic fertilizer containing both biochar and dicyandiamide.
The biochar and dicyandiamide treatment proved the most consistent. Across the full two-year rotation, it was the only organic fertilizer treatment that significantly reduced cumulative ammonia emissions compared with the conventional urea treatment. Compared with conventional organic fertilizer, adding biochar alone reduced cumulative ammonia volatilization by 5.9 per cent, while adding both biochar and dicyandiamide achieved a much larger reduction of 33.6 per cent.
Community service
The researchers linked these improvements to better regulation of nitrogen in soil and the water covering the rice crop. Biochar helped moderate ammonium concentrations and pH, two important controls on ammonia volatilization. Dicyandiamide, a nitrification inhibitor, was associated with altered nitrogen transformation patterns.
Microbial analysis also revealed changes in soil bacterial communities. Biochar-containing fertilizers reduced the abundance of nitrospirota, a group associated with nitrite oxidation, suggesting that the amendments may influence nitrification-related microbial niches.
Importantly, the environmental gains did not come at the expense of another major greenhouse gas. Cumulative nitrous oxide emissions showed no significant differences among the fertilizer treatments. The combined biochar and dicyandiamide treatment also maintained rice yields at levels comparable with conventional fertilization, whereas conventional organic fertilizer and biochar-only organic fertilizer reduced rice grain yields.
The researchers emphasize that the study was conducted in controlled soil columns rather than commercial fields. Field-scale studies are therefore needed to determine how well the approach performs under variable weather, soil, and farm management conditions.
The post Biochar and nitrification inhibitor help cut ammonia losses appeared first on Farmtario.
