Objective Excessive nitrogen application has caused yield and quality decline and environmental risks greenhouse vegetable production. We studies the appropriate amount of nitrogen fertilizer for marrow squash production based on the environmental and commercial benefit, to promote its green and efficient production, and provide references for rational fertilization of greenhouse vegetables.

Method A marrow squash field experiment was conducted in spring inside an arched shed in Pingyuan County, Shandong Province. The nitrogen application rates of 0, 195.0, 292.5, 390.0, 487.5 and 585.0 kg/hm² were setup, and top dressed with 8 drip irrigation event. The yield, quality, nitrogen use efficiency of marrow squash, as well as soil nitrogen balance were studied. The nitrogen application thresholds were calculated based on the vegetable quality, environmental safety, and commercial benefit.

Results The yield, benefit, nitrogen use efficiency, and quality of marrow squash exhibited a pronounced quadratic parabola relationship with the nitrogen application rate, with the respective maximum values corresponding to nitrogen rates of 427.8 kg/hm², 416.2 kg/hm², 310.5 kg/hm² and 228.8 kg/hm². Across all treatments, the nitrogen utilization rate varied between 14.15% and 23.14%, resulting in a significant nitrogen accumulation in soil. The residual mineral nitrogen and apparent loss in 1 m layer of soil increased significantly as the nitrogen application rate rose. Notably, when the N application rate reached 261.7 kg/hm², the nitrogen budget was approximately balanced.

Conclusions The reasonable N input threshold in spring marrow squash production inside arch shed and under drip irrigation is 288.3−386.8 kg/hm², for sustainable high income, good quality, and tolerable environmental risk.