Plastic-film mulched drip irrigation (PFMDI), a new crop management technique which combines plastic film mulching (PFM) and drip irrigation (DI), has been widely practiced in arid areas to save water. While this management enhances crop yield and respiration, the consequences for the net ecosystem carbon (C) budget (NECB) of PFMDI fields remain poorly unknown. Here, an investigation of the NECB over five years was conducted in a PFMDI cotton field in an arid oasis in Northwest China. The NECB was calculated by subtracting the C output associated with harvest from the Net Ecosystem Productivity (NEP). NEP was obtained as the reverse CO₂ flux measured with the eddy covariance (EC) method. C output associated with harvest was estimated with biomass collections. The PFMDI field lost C with the annual NECB of −67±37g C m⁻² yr⁻¹ on average. Considering CO₂ emission associated with the use of PFM and DI, C loss of the production system reached −120 g C m⁻² yr⁻¹. PFMDI enhanced both assimilation (i.e., GPP) and respiration (i.e., R_eco), but R_eco increased more than GPP, and the ratio of R_eco to GPP reached 0.93, resulting in a reduction of NEP and NECB comparing with non-PFMDI fields. Tillage increased C loss through increasing respiration while straw return decreased C loss through decreasing C output. In addition to straw return, organic fertilizer and less tillage, PFM and DI recovery should be applied in the management practices to counteract C loss in the system.

塑料膜覆盖滴灌（PFMDI）是一种结合了塑料膜覆盖（PFM）和滴灌（DI）的新作物管理技术，已在干旱地区广泛应用以节水。尽管这种管理提高了作物的产量和呼吸作用，但对于PFMDI田地的净生态系统碳（C）预算（NECB）的后果仍然知之甚少。在这里，在西北干旱绿洲的PFMDI棉田中对NECB进行了为期五年的调查。NECB是通过从净生态系统生产率（NEP）中减去与收获相关的C产出来计算的。获得NEP作为反向CO ₂用涡动协方差（EC）方法测量的磁通量。与收成有关的碳输出是通过生物量收集来估算的。PFMDI场的年NECB平均为-67±37g C m ^-2 yr ^-1时损失了C。考虑到与PFM和DI的使用相关的CO ₂排放，生产系统的C损失达到-120 g C m ^-2 yr ^-1。PFMDI增强了同化作用（即GPP）和呼吸作用（即R _eco），但R _eco的增加幅度大于GPP，R _eco的比率与非PFMDI字段相比，GPP的最大差值达到0.93，导致NEP和NECB减少。耕作通过增加呼吸作用增加了碳损失，而秸秆还田则通过减少碳输出减少了碳损失。除秸秆还田，有机肥料和耕种少之外，还应在管理实践中采用PFM和DI回收以抵消系统中的C损失。