Water-Fertilizer Coupling Model-Based Cotton Production Potential Under Drip Irrigation with Plastic Film Mulching in Xinjiang of China.

In arid Xinjiang of China, a main cotton producing area, irrigation is an important measure of agricultural production, and researches yield rich experimental data. This study aimed to establish a large-scale water-fertilizer coupling model based on comprehensive analysis of existing field experimental data to estimate cotton yield potential under drip irrigation with plastic film mulching in Xinjiang. A total of 197 datasets around Xinjiang in 1998-2015 were collected through investigation and survey, statistical yearbook, and literature retrieval. They included 19 known cotton varieties (24 datasets for unknown species) with Xinlu as main variety. Correlation and path analysis showed that cotton varieties, irrigation and N-fertilizer application rate were the main factors affecting the yield of cotton. Considering data acquisition and climatic conditions, Xinjiang was divided into North and South Xinjiang. In each region, a water-fertilizer coupling model was established based on random classification of data by different cotton varieties. The model validation showed the model was reliable with determination coefficient (R²) of 0.53, relative residual mean square error of 24.4%, and concordance index of 0.83 in the north region, and R² of 0.83, relative residual mean square error of 8.3%, and concordance index of 0.95 in the South Xinjiang, respectively. Based on the model, the optimal irrigation and N-fertilizer application rate was 604, 510 mm, and 325, and 359 kg/hm² in the North and South Xinjiang, respectively. Assuming N-fertilizer supply was adequate and available irrigation amount was 494 mm in 2020 according to Xinjiang 2014-2016 and future planning (2020), based on the established model, we estimated the yield potential of the North and South Xinjiang was 6609 and 6695 kg/hm² in 2020, respectively. The lint yield was 5 300 000 t in 2020. The actual lint yield in 2014 in Xinjiang was 3 677 000 t, reaching about 69% of the potential. The study can provide valuable information for the application of drip irrigation under plastic film mulching and agricultural water resources planning in Xinjiang.

Keywords: cotton production, drip irrigation, plastic film, Xinjiang of China, water resource