Experimental Research On Optimum Irrigation Scheduling For Moisture And Salt Regime Of Mulched Drip Irrigation Of Cotton In Arid Area

This article according to the effect of various irrigation quota and frequency of mulched drip irrigation of cotton on the moisture and salt regime were researched in field in typical area of mulched drip irrigation in Xinjiang. Research the effect of various irrigation scheduling on the salt regime characteristics and cotton yield, Then sought a optimum scheduling of mulched drip irrigation in salty areas. There were three irrigation quota of 3300, 3750 and 4200m3/ha and three frequency of 5,8 and 11 days were set in the experiment. The observation includes moisture, salt of soil, cotton growth and yield. The moisture and salt regime characteristics of various irrigation scheduling were researched. The optimum irrigation scheduling of cotton were discussed. The experimental results showed that:1. The highest variations of moisture content is at 0-20cm soil layer, and 20-40cm is lower, 40-60cm is the minimal at all of the treatments; At the same quota, the moisture content difference extent between before and after irrigation with irrigation frequency enhancing but diminution; At the same quota, the moisture content before irrigation with irrigation frequency diminution but diminution at all layers; At the layer of 0-40cm that distributing location in cotton root system most, the moisture content of the inner side and outboard cotton plant of the 5 days frequency treatments is higher, and account for more than 70%ofθf/(θf =22.5%) without exception, But the treatments of 8 and 11 days frequency is lower than 70% ofθf, The range reaching proper moisture content enhanced with the irrigation frequency enhancing.2. The soil salinity in 0-20cm layer changes mild, and 20-40cm is higher and 40-60cm is maximal at all of the treatments; At the same quota, the salinity of inner side and outboard cotton plant with irrigation frequency enhancing but diminution; At the layer of 0-40cm that distributing location in cotton root system most, in July, the salinity of the treatments were reduced except the outboard cotton plant of the 250-11 treatment, and the salinity of the inner side less than the initial salinity of 0.4% and the outboard is higher, generally at the scope of 0.4%-0.5%; In August, the salinity of the treatments were reduced except the outboard cotton plant of the 220-11 and 250-11 treatments, and the salinity of the inner side less than the initial salinity of 0.4% and the outboard is higher, generally at the scope of 0.4%-0.5%; Range that salinity reduces increased with irrigation frequency enhances; Lower frequency and lower quota easy to lead to the returning salinity at soil surface, lower quota easy to lead to the returning salinity at 20-40cm layer also and 40-60cm layer hard to happen returning salinity.3. There were not differences of cotton quality at the various treatments; There were some differences of cotton bell numbers at the various treatments, and at the same quota, the bell number increase with the irrigation frequency enhance; The cotton yield increase with the irrigation frequency enhance, and the medium quota produced the highest yield.4. The relationship between the Water Use Efficiency and irrigation quota of the three frequency increases and then decreases, and get their respective maximum value at the medium quota; The frequency of 5 days gain the highest WUE.5. The scheduling treatment of the quota of 3750 m3/ha and the frequency of 5 days is the optimum.