Controlled-release nitrogen in paddies: Bridging food security and carbon neutrality through carbon-nitrogen coupling

Abstract

Context

Widespread use of controlled-release urea (CRU) is a promising strategy to reduce nitrogen losses; however, it reduces carbon and nitrogen sequestration in the soil-plant system, limiting sustainable rice production. Research on optimizing CRU practices to enhance carbon/nitrogen processes in paddy soil-plant system remains limited.

Objective and methods

This study employed the Denitrification-Decomposition model to evaluate CRU practice for improving soil-plant system carbon/nitrogen processes, thereby enhancing food security and carbon neutrality in paddy fields under current and future scenarios.

Results

Nitrogen inputs revealed a trade-off: CRU practice required 150–206 kg N ha⁻¹ to achieve high food security and carbon neutrality, conventional urea (CU) practice required 181–202 kg N ha⁻¹. Whereas the comprehensive benefits, food security, and carbon neutrality under current CRU practices were lower than under CU, highlighting the need for improving CRU practice. Optimized CRU practice (165–197 kg N ha⁻¹) improved comprehensive benefits, food security, and carbon neutrality by approximately 60 % relative to conventional CRU practice. Nitrogen losses and NH₃ emissions primarily affected food security, while soil carbon sequestration and total carbon sequestration governed carbon neutrality. Optimized CRU practice reduced NH₃ emissions and nitrogen losses while increasing soil and total carbon sequestration. Under future scenarios, further optimized CRU practice (218 kg N ha⁻¹), with smaller N input increases compared to CU practice (247 kg N ha⁻¹), achieved higher food security and carbon neutrality than another CRU practice.

Conclusions

Optimized CRU practice mitigates greenhouse gas emissions while increasing plant carbon/nitrogen sequestration, advancing high food security and carbon neutrality.