Effect of drip irrigation and fertilizer application on water use efficiency and cotton yield in North of Xinjiang

Water and fertilizer affect a range of physiological processes in the cotton crop and are key factors controlling cotton productivity and yield. Two-year experiments(2012 and 2013) were conducted to evaluate the effects of different fertigation regimes on cotton growth, yield, water use efficiency and partial factor productivity of fertilizers in Shihezi areas of Xinjiang. The fertilization treatment was based on different ratios of N- P2O5-K2 O and the irrigation treatment was based on the crop evapotranspiration(ETC). Five fertilizer treatments were designed including 60%(F0.6), 80(F0.8), 100%(F1.0), 120%(F1.2) and 140%(F1.4) of recommended rates with N(250)-P2O5(100)-K2O(50) kg/hm2, and three irrigation treatments included 60% ETC(W1), 80% ETC(W2) and 100% ETC(W3). Irrigation amount was decided by a 20-cm inner diameter evaporation pan. Evaporation pan-crop coefficient in seedling, budding period and flowering period, boll opening period were 0.2, 0.4, 0.7 and 0.25, respectively. During the experiment, plant height, leaf area index and dry mass accumulation, and yield components were measured. Harvest index(HI), water use efficiency(ratio between yield/irrigation amounts, WUE) and partial factor productivity of fertilizer(PFP) were calculated. The results showed that compared to W3F1.0, plant height, LAI, effective bolls number per plant, seed cotton yield and quality of dry matter and WUE of W1F0.6, W1F0.8, W1F1.0, W1F1.2 and W1F1.4 treatments have dropped significantly. Besides W2F0.6 in 2013, W2 and W3 irrigation level under various fertilizer treatments, plant height were between 60 and 71 and LAI were between 3.4 and 4.2. The effective bolls number per plant of W3F1.0, W3F1.2 and W3F1.4 treatments were above 6.8 per plant. Cotton effective bolls number per plant was more sensitive than the 100-boll weight. In 2012 and 2013, the irrigation amount ranged from 291 to 445 mm and from 267 to 392 mm, cotton ET ranged from 277 to 419 mm and from 316 to 438 mm, WUE ranged from 1.27 to 1.65 kg/m3 and from 1.27 to 1.52 kg/m3 in 2012 and 2013, respectively. The highest seed cotton yield was obtained in the combination treatments of W3F1.2 and W3F1.0 with the value of 5 896 and 5 888 kg/hm2 in 2012 and 2013, respectively. W2F1.0 combination treatment had the highest WUE. PFP decreased with the increase of fertilization rate but increased with the increased irrigation amount and W3F0.6combination treatment had the highest PFP. Considering the water shortage condition in the northern Xinjiang Uygur Autonomous Region, the treatment of 80% ETC combined with 250-100-50 kg/hm2(N-P2O5-K2O) was suggested to be optimal for cotton production since the treatment could save 63 to 77 mm irrigation amount while keeping 95% seed cotton yields compared with the treatment of 100% ETC combined with 250-100-50 kg/hm2(N-P2O5-K2O). The saved water accounted for more than half amount of the averaged precipitation in this area. The study can provide valuable information for improving management of cotton crop in North of Xinjiang.