How residual plastic film affects the soil water–salt and cotton growth at the seeding stage

Abstract Cotton holds a significant position among cash crops in China, with Xinjiang serving as the primary cotton‐growing region within the country. Agricultural practices involving plastic mulching have gained importance. However, the presence of residual plastic film affects the growth of cotton seedlings as well as the soil environment. Our study aimed to explore the impact of residual plastic film accumulation on the growth of cotton seedlings and the associated soil water‐salt environment. This was done through a barrel planting experiment, utilizing soil from cotton fields with varying durations of mulching. The study showed that when the mulching period exceeded 12 years (residual plastic film content of 260.77 kg hm −2 ), residual plastic film had a significant impact on cotton seedling growth and the soil environment. Residual plastic film reduces the seedling germination rate of cotton by up to 11.11% (7 days after irrigation, 15 years of film mulching, residual plastic film content of 309.88 kg hm −2 ). It also impedes the growth of cotton seedlings; plant height, stem thickness, and leaf area were reduced by 34.52%, 10.73%, and 37.18%, respectively (19 days after irrigation, 15 years of film mulching, residual plastic film content of 309.88 kg·hm −2 ). Compared with the treatment without residual plastic film, the shallow soil water content in the T5 treatment decreased by 1.19% (10 days after irrigation, 15 years of film mulching, residual plastic film content of 309.88 kg·hm −2 ). Residual plastic film in cotton fields subjected to long‐term mulching obstructs the normal growth and development of cotton seedlings while also impacting the transport of soil water and salt. Therefore, we recommend adopting biodegradable mulch or regularly recycling residual plastic film within mulched areas to prevent its accumulation and subsequent negative impacts.