Fertigation combined with catch crop maximize vegetable yield and minimize N and P surplus

Excessive fertilization is a common agricultural practice that often results in high risk of nitrogen (N) and phosphorus (P) losses in vegetable production in China. To reduce these losses, it is crucial to control residual nutrient levels in the rootzone and maintain crop growth. A 3-year field experiment was therefore conducted to investigate the effects of optimal fertigation (OF), OF combined with summer catch crop (OF-SCC; sweet corn with residue incorporation after harvest) or wheat straw application (OF-WSA; soil amended with wheat straw before cucumber seedling transplanting) on soil nutrients, soil residual N and P levels in the rootzone. The conventional management (flood irrigation with excessive fertilization and bare fallow during the summer period) served as control. The results showed that, although OF reduced irrigation amount, N input and P input by 49, 50 and 53%, respectively, it did not affect N and P uptake and fruit yields, and significantly reduced N and P surplus in the rootzone by 60 and 59%, respectively, when compared to the control. The SCC extracted 72–74 kg N ha^?1 year^?1 and 10–13 kg P ha^?1 year^?1 from soils. In addition, SCC and WSA increased soil soluble organic N in the rootzone but had little influence on N and P surplus. Generally, OF was efficient in reducing soil residual N and P, while SCC could temporarily retarded N leaching and improved nutrient recycling in the rootzone. Our results infer that OF combined with SCC is an efficient method for reducing soil N and P losses.