Effects of Spring Irrigation on Water and Salt Distribution in Soil and Cotton Growth in Southern Xinjiang

Abstract

【Objective】 Soil salinity is an abiotic factor facing agriculture production in Xinjiang, and a common remediation is to leach the salt out of the root zone before planting. Taking cotton as an example, this paper studied the efficacy of pre-planting drip irrigation in desalinizing the soil and sustaining cotton growth. 【Method】 The experiment was conducted in a cotton field. It consisted of two pre-treatments: drip-irrigating 90 mm of water before seed drilling, and conventional flooding irrigation using 180 mm of water before seed drilling. After that the crops were watered ten times using mulched drip irrigation, each irrigating 30 mm (W1), 37.5 mm (W2) or 45 mm (W3) of water. During the experiment, we measured the changes in soil water and salt contents, growth, dry matter accumulation, yield, and water use efficiency of the crop in each treatment. 【Result】 Compared with conventional flooding spring irrigation, spring drip irrigation kept soil moistened enough for seedling emergence; it also significantly increased water content in the 0~80 cm soil layer during the whole growing period. Salt accumulated in the 0~40 cm soil layer, with its EC at bud and boll stages increasing by 7.84% and 8.75%, respectively, compared to that at seedling stage. Soil EC increased as time elapsed in all treatments, but the increase decreased as the irrigation amount increased, with EC in the 0~100 cm soil layer in W1, W2 and W3 increasing by 30.11%, 12.12% and 11.11%, respectively. Increasing irrigation amount also improved plant height, stem diameter, dry matter accumulation, yield and water use efficiency, but reduced irrigation water use efficiency. There was no significant difference in yield and water use efficiency between W1 and W3 regardless of the spring irrigations, but the yield and water use efficiency in W2 differed significantly between the two spring irrigations. 【Conclusion】 Considering cotton yield and water use efficiency, the optimal irrigation quots for the whole growth period is 45 mm combined with a spring drip irrigation of 90 mm to leach the salt out of the root zone. For conventional spring irrigation to leach the salt, the irrigation quots of the 10 subsequent irrigations can be reduced to 37.5 mm in which the seeded cotton yield reached 7 207.81 kg/hm2.

Keywords

• drip seeding
• cotton field under film drip irrigation
• water and salt distribution
• yield
• water use efficiency