Plastic mulching with drip irrigation increases soil carbon stocks of natrargid soils in arid areas of northwestern China

• We compared SOC, SIC, and total C stocks from the mulching and non-mulching cotton fields.
• Plastic film mulching PC adoption increased not only SOC but also SICS stock in the soil of 0–70 cm layer.
• Conversion from traditional NPC to PC systems could sequestrate carbon of 0.48 kg C m− 2 into the soil.
• Plastic film mulching practice was an effective method for soil C sequestration in arid farmland.

A cotton field experiment was conducted to study the effects of plastic film mulching cultivation (PC) and non-mulching cultivation (NPC) on soil carbon content of an Aridisol, classified as a typic natrargid, in Xinjiang Uygher Autonomous Region, China. The use of PC enhanced the stock of soil organic carbon (SOC) at depths of 0–30 cm, but not at depths of 30–70 cm, compared with NPC. Furthermore, PC enhanced the stock of soil inorganic carbon (SIC) at depths of 30–70 cm but not at 0–30 cm. Overall, PC increased the total carbon (TC) stock at depths of 0–70 cm. The TC stock was higher in PC (16.37 kg C m− 2 year− 1) than in NPC (15.89 kg C m− 2 year− 1). The contribution percentage of SIC (52%) to the net soil carbon (C) accumulation was higher than that of SOC (48%). Our results suggested that adoption of PC could be used as an effective way to increase the carbon sequestration of soils under cotton systems in arid areas.