Drip fertigation with straw incorporation significantly reduces NO emission and N leaching while maintaining high vegetable yields in solar greenhouse production.

Approximately 1/3 of vegetables in China are produced in solar greenhouses. Most farmers use conventional irrigation with over fertilisation (CIF), thereby applying approximately 2000 kg N ha fertiliser over two cropping seasons per year. Here, we tested the effect of drip irrigation with reduced fertilisation (DIF) combined with straw incorporation on reducing NO emissions and nitrogen leaching from solar greenhouse vegetable production systems. Over three consecutive tomato cropping seasons, NO emissions and nitrogen leaching were monitored in high temporal resolution, thereby producing a unique dataset. Compared to CIF, the realised drip fertigation scheme reduces NO emission and nitrogen leaching of nitrate and dissolved organic nitrogen by approximately a factor of 5-10 (NO-DIF: 10.3, CIF: 47.5 kg N ha yr; N leaching-DIF: 83.6, CIF: 863 kg N ha yr). Straw incorporation in CIF, though advantageous for soil health, resulted in pollution swapping as soil NO emissions increased while NO leaching losses decreased. On the contrary, no significant negative environmental N effects of straw incorporation were found for DIF. As crop productivity was not affected by straw incorporation, neither for CIF nor for DIF, our study provides a sound basis for policy advice to recommend farmers to adopt drip fertigation combined with straw application. Wide scale adoption of this technique will result in reductions of environment N losses, alleviate major soil degradation signs, including soil acidity, nutrient imbalance and deterioration of soil microbial community structure, while allowing to maintaining high yields of vegetables in solar greenhouse production systems.