滴灌方式及定额对北疆冬灌棉田土壤水盐分布及次年棉花生长的影响

为探寻解决干旱区棉田冬季灌水问题,明晰北疆棉田不同冬灌方式及灌水定额对土壤水分、盐分分布以及翌年棉花生长及产量的影响,采用大田试验方法,以未冬灌大田作为对照(CK),设置滴灌和漫灌2种灌水方式下4个梯度的灌水定额(1 800、2 400、3 000、3 600、 3600 m3/hm²)共9个处理进行冬灌试验,分析了冬灌灌水后到播种前0~300 cm土层的水分、盐分的动态变化以及翌年各处理棉花的出苗率、群体生理指标(群体光合势、群体净同化率、叶面积指数)和产量数据。结果表明,冬灌对次年播前土壤水盐分布及含量的大小均具有一定的影响,无论漫灌还是滴灌方式进行冬灌,随灌水定额增加土壤水分和盐分的影响深度也随之加深,灌水定额达到3 000和3 600 m3/hm²时,冬灌对土壤水盐影响深度可达300 cm。冬灌可显著改变次年播前土壤盐分的自然分布状态,有效淋洗并降低上层土壤盐分含量；相对漫灌方式而言,滴灌冬灌方式土壤水分入渗更加均匀且规律明显。冬灌对次年滴灌棉花的生长发育及产量均具有重要影响,冬灌后次年棉花群体指标与未冬灌处理的差异随冬灌灌水定额的增加愈加显著,灌水定额3 000 m3/hm²滴灌冬灌处理的次年棉花群体光合势与叶面积指数较未冬灌处理分别提升34.30%和42.60%；冬灌有利于次年棉花产量的提高,滴灌冬灌灌水定额3 000、3 600 m3/hm²处理时的棉花产量相对未冬灌处理分别增产10.66%和12.36%。综合考虑冬灌方式及灌水定额对次年土壤水盐分布及棉花生长和产量的影响,研究认为滴灌条件下灌水定额3 000 m3/hm²的冬灌在试验条件下比较适宜,既可淋洗盐分至耕层以下300 cm处,亦可获得6 107.75 kg/hm²的较高产量。

Effects of winter drip irrigation mode and quota on water and salt distribution in cotton field soil and cotton growth next year in northern Xinjiang

A field experiment was carried out in order to explore the winter irrigation on cotton field in arid region.Influences of winter irrigation pattern and irrigating water quota for cotton field in northern Xinjiang on soil water and salt distribution as well as cotton growth and yield in the next year were discussed.From October in 2013 to October in 2014, Key Corps Laboratory for Modern Water saving Irrigation of Shihezi University, carried out the field experiment.Field without winter irrigation was taken as the control group(CK).The winter irrigation experiment set a total of 9 test groups, including 2 irrigation patters (drip irrigation and flood irrigation) and 4 irrigation water quotas: DI-1800(drip irrigation, irrigation quota of 1 800 m3/hm²), DI-3000(drip irrigation, irrigation quota of 3 000 m3/hm²), DI-2400(drip irrigation, irrigation quota of 2 400 m3/hm²), DI-3600(drip irrigation, irrigation quota of 3 600 m3/hm²), FI-1800(flood irrigation, irrigation quota of 1 800 m3/hm²), FI-3000(flood irrigation, irrigation quota of 3 000 m3/hm²), FI-2400(flood irrigation, irrigation quota of 2 400 m3/hm²), and FI-3600(Flood irrigation, irrigation quota of 3 600 m3/hm²).We used soil drilling and drying method to measure soil moisture content, and electric conductivity method to measure soil salt content, and we observed and measured the cotton growth situation for each treatment and growth stage to determine population physiological index.Dynamic changes of water and salt in 0~300 cm soils before sowing, rate of emergence, population physiological indices(leaf area duration, net assimilation rate, and leaf area index) and cotton yields in the next year of all testing groups were monitored and compared.When comparing the effect of irrigation, we found water spread and infiltrated evenly under drip irrigation situation, the infiltration speed was slow, and the water retention effect was considerably good; under the circumstance of flood irrigation, the irrigation speed was fast, the infiltration was uneven and waterlogging occurred in the cultivation layer.Results showed that winter irrigation had certain impact on water and salt content and distribution in soil profile before sowing in the next year.For both flood irrigation and drip irrigation, the influence of irrigation on water and salt contents was intensified with the increase of irrigation water quota.Winter irrigation could leach and reduce salt contents in superficial soils.Salt distribution in soil profile(especially 0~150 cm soils) before sowing was greatly influenced by winter irrigation.Due to the strong leaching effect of winter irrigation on soil salt content, it could provide good water and salt environment for crop growth.Compared to flood irrigation, drip irrigation provided more uniform and regular water infiltration.Drip irrigation in winter had an important role on cotton growth and yield in the next year.Difference of population indices between testing groups and CK increased with the increase of irrigation water quota.Appropriate irrigation water quota could increase the rate of cotton emergence in the next year and improve the population indices in early period significantly.Under winter drip irrigation with the quota of 3 000 m3/hm², the cotton canopy photosynthetic potential, group net assimilation rate and leaf area index improved respectively by 34.30%, 19.23% and 42.60% compared with those without winter irrigation treatment, and the photosynthesis potential and leaf area index reached peak value 10 days in advance.The leaf area index peak under 3 000 m3/hm² drip irrigation was 10 d earlier than CK and higher than that under the flood irrigation.Winter irrigation also could increase cotton yield in the next year.The cotton yields under 3 000 and 3 600 m3/hm² drip irrigation were 10.66% and 12.36% higher than that under the CK.Based on the comprehensive considerations to the effect of winter irrigation pattern and irrigation water quota on soil water and salt distributions as well as cotton growth and yield in the next year, this paper concludes that 3 000 m3/hm² drip irrigation is the optimum one.It can not only leach soil salts as deep as 300 cm, but also contribute a high yield, reaching 6 107.75 kg/hm².