Water–fertilizer coupling balances yield and the input-related carbon footprint in double-cropping greenhouse Hami melon

Abstract

Water–fertilizer management is central to balancing productivity and environmental performance in greenhouse agriculture. Methods: In a spring–autumn greenhouse Hami melon system in Xinjiang, five irrigation (W1–W5) and three fertilization (F1–F3) levels were combined. Life cycle assessment quantified the input-related carbon footprint, plant carbon storage was measured, and structural equation modeling (SEM) evaluated associations among inputs, biomass, yield and carbon-footprint intensity. Results: Production inputs generated 12.77 t CO 2 -eq ha -1 , with fertilizers (54.52%) and plastic film (23.16%) as the main sources. W4F3 achieved the highest yields (75.74 and 52.79 t ha -1 in spring and autumn, respectively) and plant carbon storage (up to 35.78 g C plant -1 ). In the fitted SEM, yield was strongly negatively associated with product carbon-footprint intensity (β = −1.253, P < 0.001), whereas area-based emissions were positively associated with it (β = 0.729). Under low irrigation, increasing fertilization did not consistently increase yield, while adequate water enabled fertilizer inputs to be converted more effectively into biomass and yield. Conclusion: Under the tested sandy-soil, cultivar and one-year greenhouse conditions, W4F3 (approximately 3420 m 3 ha -1 irrigation and 863 kg ha -1 fertilizer) provided the most favorable balance between yield and product carbon-footprint intensity.