Assessing the Impact of Mulching-Induced Warming on the Zoning of Machine-Picked Cotton Planting Areas Based on Selected Indicators

The 20th century, global temperatures underwent significant changes, impacting agricultural climate zones worldwide. Xinjiang, China, a key player in machine-picked cotton production, was influenced by various heat-related indicators(sum of active temperature ≥ 10℃、mean temperature in July、climatological growing season length, April-May sum active temperature、Last spring frost, and Defoliator spray time). Using meteorological data from 58 weather stations in Xinjiang, we examined the spatio-temporal trends of these indicators during the period of 1981-2020. Additionally, we considered the effects of climate warming and plastic mulching on the sowing area and zoning area of machine-picked cotton in different suitable zones. Overall, Xinjiang experienced an trend in heat resources, with a pattern of more in the southern part than the northern part, and more in plains and basins than in mountainous areas. Under climate warming conditions, the sowing area of the most suitable cotton zone and the suitable cotton zone has increased, while the sowing area of the moderately suitable cotton zone and unsuitable cotton zone has decreased. Under the plastic mulching mechanism, a comparison of the zoning area and sowing area from 1991 to 2020 revealed that there was no difference in the zoning area of the most suitable zone compared to the sowing area, while the zoning area of the suitable zone increased by 15.7% (2.15×103km2) compared to the sowing area. The zoning area of the moderately suitable zone decreased by 14.5% (0.26×103km2), and the unsuitable zone decreased by 7.8% (0.17×103km2) compared to their respective sowing areas. These results indicate that climate warming and plastic mulching have increased the cultivable area of machine-picked cotton in Xinjiang, but there are also instances of unreasonable zoning. It is necessary to allocate land resources reasonably based on climatic conditions to ensure the healthy development of the cotton industry in Xinjiang.