Mitigating N leaching and N₂O emissions by combining drip irrigation and reduced fertilization with straw incorporation in greenhouse tomato systems

Severe nitrogen (N) leaching and increased N 2 O emissions are major environmental risks for greenhouse vegetable production systems (GVPS) that depend on flood irrigation and overfertilization. Comprehensive research on reducing both simultaneously, however, remains scarce due to their complex trade-off dynamics. In this study, a field experiment was carried out across three tomato growing seasons in GVPS in North China to measure N leaching and N 2 O emissions under four management practices: CIF (conventional flood irrigation and fertilization), CIFS (CIF + straw), DIF (drip fertigation with reduced N), and DIFS (DIF + straw). The WHCNS_Veg model, calibrated and validated with field data, and quantified the effects of different management practices on drainage, nitrate and dissolved organic nitrogen (DON) leaching, N 2 O emissions and yields. Compared to conventional fertilization with flood irrigation, drip irrigation with reduced N application decreased average seasonal drainage, N leaching (nitrate and DON) and N 2 O emissions by 79.3 %, 84.6 % and 82.6 %, respectively. Additionally, it enhanced average seasonal yield, water use efficiency and N use efficiency by 13.0 %, 34.7 % and 147.3 %, respectively. Under flood irrigation, compared to CIF, CIFS reduced overall average seasonal total N leaching by 7.9 % due to a 19.0 % reduction in average seasonal nitrate leaching, but increased average seasonal DON leaching and N 2 O emissions by 112.9 % and 94.2 %, respectively. Under drip irrigation, straw incorporation had minimal impact on N losses while maintaining high yields. Therefore, combining drip irrigation with reduced N application and straw incorporation is recommended for sustainable and high-yield GVPS cultivation. • WHCNS_Veg model performed well for simulating N leaching and N 2 O emission. • Drip fertigation reduced N leaching by 84.6 % compared to flood irrigation. • Straw addition nearly doubled DON leaching and N 2 O emission under furrow. • Straw return with drip irrigation had little effect on N leaching and N₂O emission. • Drip fertigation with straw incorporation is recommended for sustainable GVPS.