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【Background and objective】 Evaporation and its associated salt accumulation on the soil surface is an abiotic stress facing agricultural production in arid and semi-arid regions, and how to alleviate its detrimental impact is a topic that continues to attract interest from both researchers and practitioners. Cutting the capillary connection in soil is one technology and the purpose of this paper is to investigate the feasibility of burying a straw interlayer in soil to slow down evaporation and salt migration from groundwater. 【Method】 The experiments were conducted in columns filled with saline soil taken from a cotton field that has been watered by film-mulched drip irrigation in southern Xinjiang. The groundwater table was controlled at the depths of 1.0 m, 1.5 m and 2.0 m respectively, with a cotton straw interlayer buried at a depth between 15 cm and 60 cm from the soil surface. In each treatment, we measured water evaporation and salt accumulation on the soil surface. 【Result】 ①The cumulative evaporation and daily evaporation rate both decreased as the groundwater table depth increased, with the average daily evaporation rate being 1.73 mm/d, 1.12 mm/d and 0.49 mm/d, respectively, when the groundwater table was 1.0 m, 1.5 m and 2.0 m deep. The cotton straw layer reduced water evaporation with the reduction depending on its burying depth. The reduction was the highest when its buying depth was 15 cm, and the least when the burying depth was 30 cm. ②Salt accumulation in 0~30 cm soil layer decreased as the groundwater depth increased, with daily accumulation rate being 0.031 g/kg/d, 0.012 g/kg/d and 0.004 g/kg/d, respectively, when the groundwater table depth was 1.0 m, 1.5 m and 2.0 m without the straw layer. The efficacy of the straw layer in reducing evaporation was more noticeable in the early stage of the experiment, and was most effective when being buried at the depth of 15cm. When groundwater table was 1 m, 1.5 m and 2.0 m deep, burying the straw 15 cm deep reduced daily slat accumulation in the 0~30 cm of soil by 71.25%, 87.15% and 90.58%; 41.91%, 37.85% and 34.90%; and 20.45%, 26.63% and 33.33%, respectively, compared with that buying it at 30 cm, 45 cm and 60 cm deep. ③The accumulated salt in 0~30 cm soil increased linearly with soil water evaporation. 【Conclusion】 The accumulated salt on the soil surface and daily evaporation from groundwater both decreased as groundwater depth increased. Regardless of its burying depth, the cotton straw layer reduced groundwater evaporation and salt accumulation in 0~30 cm soil, but it was most effective when being buried at the depth of 15 cm. We also found that the accumulated salt in the 0~30 cm soil increased linearly with water evaporation.

In recent years, with the development of agriculture in southern Xinjiang, water and land resources shortage is increasingly prominent. Water-saving irrigation methods to efficiently use water resources and increase farmers' income have been proposed by Xinjiang Production and Construction Corps. Meanwhile, land resources and crop planting structure are adjusted and characteristic wood's fruit industry is developed. Jujube-cotton intercropping system in southern Xinjiang is a new type of agroforestry systems. It is unclear about the effect of jujube-cotton intercropping system with drip-irrigation on cotton growth and land use efficiency and the related mechanisms. This study aimed to investigate the influence of drip-irrigation quota on growth, yield and land use efficiency of cotton in jujube-cotton intercropping system. A field experiment was conducted in 2012 and 2013 using a randomized complete block design with jujube planting spacing of 1 m × 3 m, cotton planting spacing of 0.25 m × 0.60 m, and cotton and jujube spacing of 0.95 m. Drip-irrigation quota was 450 (GM-1), 750 (GM-2), and 1050 m3/hm2 (GM-3) for intercropping system and 750 m3/hm2 for cotton (CK-M) and jujube (CK-Z) monoculture. The stem height, diameter, aboveground dry matter, and yield of cotton were measured. The land equivalent ratio and system productivity index were calculated. The results showed that the cotton stem height was highest in the GM-3 among all treatments, and not significantly (P>0.05) different between GM-1 and GM-2. The changes in the stem diameter were similar with the height. The GM-3 treatment could adversely affect the cotton aboveground dry matter accumulation, but the GM-1 and GM-2 had similar role in increasing the cotton aboveground dry matter accumulation. The land equivalent ratio in the intercropping system was larger than 1, and greater than the monoculture system. For the two years of the experiment, the GM-2 treatment had the steadily highest land equivalent ratio and yield. Land use efficiency in jujube-cotton intercropping system was higher than the monoculture system. In addition, the system productivity index of GM-2 was relatively higher than the other treatments. In the intercropping system, the jujube was easily affected by irrigation amount and thereby its yield and productivity could be affected. The treatment of GM-2 could increase the production potential of jujube. The jujube-cotton intercropping system had a higher capacity to withstand market risks. In summary, the irrigation of 750 m3/hm2 had high land use efficiency and thus could be favorable to cotton growth and land use. The study suggested that optimal production capacity could be reached through reasonable irrigation in intercropping system. The results provided valuable information for the water resource use, and efficient land use in southern Xinjiang. [ABSTRACT FROM AUTHOR]