地膜覆盖时间对绿洲覆膜滴灌棉田土壤盐分时空变化的影响

Temporal and Spatial Dynamics of Soil Salinity after Different Durations of Plastic Film-based Mulching in a Drip-irrigated Cotton (Gossypium hirsutum L.) Field in Southern Xinjiang, China

【目的】地膜覆盖技术广泛应用于中国西北内陆的棉花生产,然而地膜覆盖周期对土壤物理性质的影响知之甚少,本文旨在探讨不同地膜覆盖时间对绿洲棉田土壤盐分时空变化的影响,并明确最佳的地膜覆盖周期。【方法】以南疆绿洲灌溉棉田为研究对象,设置不同的地膜覆膜时间,比较地膜覆盖40 d、55 d、70 d、85 d、100 d和全生育期覆盖处理,棉田土壤含水量及含盐量在水平和垂直二维空间的差异,明确其对土壤盐分分布及运移规律的影响。【结果】随着覆膜时间的增加,土壤平均含水量逐渐增加,与CK相比,覆膜40~85 d土壤含水量降低14.5%~7.5%,覆盖100 d处理则高出4.4%。土壤平均含盐量随覆膜时间的缩短而增加,其中对0~40 cm土层的影响较大,对60~80 cm土层的影响较小。覆膜时间越长则抑盐效果越明显,但覆盖时间超过100 d后,地膜保水抑盐效果下降。【结论】地膜覆盖时间在85~100 d抑盐效果与全生育期覆膜相当,该结果为土壤盐渍化治理以及明确残膜适宜回收时期提供了理论依据。

[Objective]Plastic film-based mulching is widely used to improve water harvesting and crop productivity in semiarid areas.It is also extensively used for cotton(Gossypium hirsutum L.)production in inland northwestern China,especially in temperature-and rainfall-limited areas.However,it is unclear whether the technology can sustainably maintain the soil water level and salt balance.The primary objectives of this study were as follows:(i)to determine whether different durations of plastic film-based mulching influenced temporal and spatial variations in soil salinity in drip-irrigated cotton fields;and(ii)to determine the optimum duration for plastic film-based mulching.[Method]We imposed six treatments,plastic film-based mulching continuously for 40,55,70,85,and 100 d,as well as a control(CK)for the whole growth period,in drip-irrigated cotton fields in the oasis of southern Xinjiang.[Result]The mean soil water content in the 0–80-cm layers increased as the plastic film-based mulching duration increased.Compared with CK,the soil water content decreased from 14.5%to 7.5%from 40 d to 85 d,and the soil water content of the 100-d film mulching treatment was 4.4%greater than that of the CK.The average soil salt content increased as the plastic film-based mulching duration decreased,and there was a greater influence on the 0–40-cm soil layer than on the 60–80-cm soil layer.The longer the film mulching duration,the greater the salt suppression effect.However,after a plastic film-based mulching duration of more than 100 d,the moisture preservation and salt suppression began to decline. [Conclusion] The 85-d to 100-d period in which salt suppression was associated with plastic film-based mulching approximately covers the whole cotton growth period. These results provide a theoretical basis for the control of soil salinization and for maintaining high yields in the cotton fields of Xinjiang.