Distribution characteristics of residual film over a cotton field under long-term film mulching and drip irrigation in an oasis agroecosystem

• Published in: Soil & tillage research 2018-08, Vol.180, p.194-203
• Main Authors: He, Huaijie, Wang, Zhenhua, Guo, Li, Zheng, Xurong, Zhang, Jinzhu, Li, Wenhao, Fan, Bihang
• Format: Article
• Language: English
• Subjects: Agriculture management; Agriculture pollution; Mulching drip irrigation; Residual mulching film; Xinjiang
• ISSN: 0167-1987; 1879-3444
• DOI: 10.1016/j.still.2018.03.013

•Distribution of residual plastic film (RPF) in soils was examined in cotton fields•Total mass of RPF declined with depth, and RPF frequency maximized at 5–15 cm depth•RPF accumulated with the continuous mulching practice at 15.69 kg ha−1 per year•RPF became more fragmented and migrated to deeper after constant mulching practice•Current mulching method pollutes soils and risks the sustainability of agriculture Without an efficient mulch film recovery, the residual plastic film (RPF) causes pollution hazards to agronomic systems and natural environments. Here, we examined the distribution characteristics of RPF in the topsoils (0–40 cm) in an oasis agroecosystem in Northwest China. After cotton harvest in 2016, we collected 2304 soil samples from six cotton fields with different years of continuous mulching management (5, 9, 11, 13, 15 and 19 a). A total of 2471 pieces of RPF were separated and weighted. The weight of each RPF fragment was calibrated by its size measured in digital images. Our results showed that the amount of RPF ranged from 121.85 to 352.38 kg ha–1 across the six fields, remarkably exceeding the national standard of China (75 kg ha–1). The occurrence frequency of RPF fragments maximized at 5–15 cm depth. With the increase in soil depth, RPF fragments became smaller, and their total mass decreased linearly. After the constant mulching practice, RPF accumulated at an annual rate of 15.69 kg ha−1, mainly occurring at 0–30 cm depth. The accumulation of the larger RPF fragments (>25 mg per piece) primarily took place from 5 to 15 years after mulching started. It took over 15 years for the larger RPF fragments to degrade into smaller ones (