Evaluating effects of four controlling methods in bare strips on soil temperature, water, and salt accumulation under film-mulched drip irrigation

Film-mulched drip irrigation as an effective water saving irrigation method has been widely utilized in arid areas. Unnecessary soil-water loss and excessive salt accumulation from soil evaporation, however, still occur in the bare strips between adjacent films under drip irrigation so that developing a useful method to combat this has been a challenge. Applying the methods of soil evaporation control in the bare strips under film-mulched drip irrigation may alleviate this problem. In 2013 and 2014, we thus adopted four controlling methods (STM: straw mulching, SAM: sand mulching, PAM: polyacrylamide amendment application, and CSS: surface soil compaction) in bare strips to evaluate their effects on soil properties and cotton productivity under film-mulched drip irrigation in southern Xinjiang, northwestern China. The main results showed that the four controlling methods gave more stable daily soil temperatures in bare strips with respect to CK. In general, STM and PAM reduced the soil temperature while CSS and SAM increased it. Moreover, the four controlling methods effectively reduced daily soil evaporation by 34.6-96.2% and 61.1-77.3% in 2013 and 2014, respectively. Lower evapotranspiration was found in the four controlling methods. The salt accumulation amount from late seedling stage to harvest reduced greatly in the four controlling methods, especially in STM and PAM. There were no significant differences in cotton yield and water-use efficiency (WUE), but the WUE for the four controlling methods slightly increased by 10.2-12.2% and 1.1-8.5% in 2013 and 2014, respectively, with respect to CK. The highest yield and WUE were found in SAM during the both seasons, indicating that SAM could be more effective than the other controlling methods at the experimental site. The controlling methods in bare strips under film-mulched drip irrigation can provide an alternative option to prevent the risk of soil salinization and enhance crop productivity in the arid regions of Xinjiang and other similar regions in the world. However, long-term use of the controlling methods in bare strips under film-mulched drip irrigation should be further evaluated.