【摘要】 通过膜下滴灌大田试验研究了3种不同滴头流量处理(Ⅰ=1.8 L/h、Ⅱ=2.6 L/h、Ⅲ=3.2 L/h)下滴灌对棉田土壤盐分变化的影响。结果表明:滴灌结束后,空间尺度上土壤盐分的水平和垂直运移距离均随着滴头流量的增加呈现先增加后减小的趋势,在时间尺度上,随着时间的推移,土壤盐分呈现从膜下到膜间的迁移趋势。在滴水定额为4 500 m3/hm2条件下,在0~40 cm土层内,3种滴头流量处理下滴灌之后土壤平均含盐量均呈明显的减小趋势,处理Ⅰ、Ⅱ、Ⅲ的脱盐率分别为13.5%、40.4%、14.6%,其中处理Ⅱ的脱盐效果最好,其次是处理Ⅲ;而在0~120 cm土层内,所有处理下的土壤平均含盐量的下降幅度均不明显。在0~40 cm土层内,3种滴头流量处理下棉花收获后土壤平均含盐量均呈减小的趋势,但在0~120 cm土层中,膜间土壤呈积盐状态,其中处理Ⅱ的积盐率最小,为1.9%,因此采用2.6 L/h的滴头流量为最适宜的滴水强度,这对于浅层(根层)土壤盐分的淋洗作用明显。更多还原

【Abstract】 Because of the irrigation regime and natural factors,soil salinization has become more and more severe in arid regions.Making an appropriate irrigation regime to leaching soil salinity is a key scientific issue under drip irrigation in the silt loam soil in arid region.A 3-year field experiment was carried out to investigate the effects of different drip irrigation regimes on soil salinity distribution and cotton yield at Akesu Agricultural Ecosystem National Research Station,Chinese Academy of Sciences.Based on the field experiment,the effects of three different emitter discharge rates of 1.8 L/h,2.6L/h and 3.2 L/h on soil salt dynamics in cotton field were studied under drip irrigation with mulching condition in arid regions.The results show that the redistribution of soil water determinates the distribution of soil salt.Throughout cotton growing season,the average water content of soil was arising gradually.The peak cure of soil salt under mulch moved downward with the increases of drip irrigation discharge rates,the drip irrigation discharge rates increased from 1.8 L/h to 2.6 L/h,peak value of soil salt moved downward from 45 cm to 65 cm.On the other hand,the soil salinity had a decreasing trend from emitter distance with the increasing of emitter discharge rate after drip irrigation.The peak cure of soil salt under mulch moved downward with the increases of drip irrigation discharge rates for all treatments except 3.2 L/h treatments because of the capability of infiltration of porosity of soil less than the drip irrigation discharge rate.The peak cure of soil salt under mulch decreased in the order 2.6 L/h>1.8 L/h>3.2 L/h after irrigation.The soil salinity moved gradually from deep soil to surface soil and moved slowly from under mulch to inter-mulch simultaneously with elapse time.Under the drip irrigation amount of 4 500 m3/hm2,in 0-40 cm soil layer,the average soil salinity decreasing evidently under three treatments after irrigation,their desalinization rates were 13.5%,40.4% and 14.6% respectively,the ratio of leached soil salt of treatment Ⅱ reached maximum value.Contrasting to 0-40 cm soil layer,the average soil salt contents for all treatments were increasing in 0-120 cm soil layer at the end of experiments,the average soil salt content of treatmentⅠ,treatmentⅡ and treatmentⅢ increased 0.02,0.01 and 0.03,respectively,their salinization rates were 3.3%,1.9%,4.9%.Average soil salinity of the 0-120 cm soil layer had an unevidently decreasing trend simultaneously.Average soil salinity had an increasing trend in 0-120 cm soil layer,while that decreasing in 0-40 cm soil layer under three treatments after harvesting,through the whole cotton growing season,the accumulation of soil salt of treatments Ⅱ reached minimum value simultaneously.Treatments Ⅱ(2.6L/h) is the best emitter discharge rate to leach for the rhizosphere under the drip irrigation amount of 4 500 m3/hm2 in arid regions.Therefore,appropriate drip irrigation discharge rate of 2.6 L/h is the best drip irrigation regime for leaching soil salinity under drip irrigation in the silt loam soil in arid region.更多还原