不同灌溉制度对南疆棉田水盐分布及作物生长的影响

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

【目的】探究不同春灌策略下膜下滴灌棉田生育期适宜灌溉定额。【方法】通过大田小区试验,设计播前滴水春灌(春灌量90 mm)和常规春灌(春灌量180 mm)2种春灌模式,每种模式下在棉花生育期设计3种灌水定额(W1:30 mm、W2:37.5 mm、W3:45 mm)处理,研究春灌模式与灌水定额对膜下滴灌棉田土壤水盐动态变化、棉花生长、干物质积累、产量和水分利用效率的影响。【结果】与常规春灌相比,滴水春灌能够保证棉花苗期出苗所需的土壤水分,且能显著提高生育期0~80 cm土层的土壤含水率;与苗期相比,滴水春灌棉花生育期0~40 cm土层出现积盐区,蕾期和花铃期0~40 cm土层电导率分别增加了7.84%和8.75%,滴水春灌生育期末0~100 cm土层土壤电导率较常规春灌增加8.37%;不同灌水定额下0~100 cm土层土壤电导率均呈增加趋势,但随着灌水定额的增加土壤剖面电导率显著降低,W1、W2、W3处理积盐率分别为30.11%、12.12%和11.11%;随着灌水定额的增加,株高和茎粗显著提升,干物质积累量明显增加,产量增加,而灌溉水利用效率(WUEI)减小,水分利用效率(WUEET)增大;在W1、W3灌水定额下,不同春灌模式间产量和水分利用效率无显著差异,但在W2灌水定额下,不同春灌模式间产量和水分利用效率差异显著。【结论】从棉花产量和水分利用效率方面综合考虑,滴水春灌模式下,灌水定额推荐为45 mm(W3);常规春灌模式下,灌水定额为37.5 mm(W2),全生育期灌水10次,可以获得合理的盐分分布与脱盐效果,籽棉产量为7 207.81 kg/hm^(2),是实现抑盐、控水、高产的适宜棉花灌溉制度。

【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/hm^(2).