干旱区膜下滴灌棉田表层土壤盐分日内动态特征

利用便携式土壤盐分计测量膜下滴灌棉田不同位置和不同深度的土壤电导率,来研究膜下滴灌条件下表层土壤电导率的日内变化特征.结果显示:干旱区一膜两管膜下滴灌条件下,窄行处土壤电导率值最低,膜间最大,宽行居中,表层土壤电导率值存在显著的日内变化特征,早晚土壤电导率值低,中午电导率值高,上午的上升速率大于下午的下降速率；窄行处相对变化幅度大,膜间绝对变化幅度大,土壤电导率值日内变化幅度随深度呈减小趋势；膜下滴灌情况下,表层土壤电导率值的变化受土壤温度和气温的影响显著,但二者相关性复杂,不同深度、不同时间段的相关性不同,膜间大多呈显著正相关,窄行大多呈非显著正相关,宽行处上午呈非显著正相关,但下午呈显著负相关.

Hourly Variant of Soil Salinity under Film-Mulched Drip Irrigated Cotton Field in Arid Area

According to the measured value of soil electrical conductivity(EC) in different depth and different location in cotton field by film-mulched drip irrigation using soil conductivity meter called EC100 in the summer of 2010,the hourly variant of soil salinity in the depth from 1 cm to 15 cm was analyzed.The results showed the following conclusions.For the film-mulched drip irrigation of two pipes under the film,the surface soil EC under the narrow row was lowest because it was under the water emitters,and that under the inter-films was largest because it was naked and easily affected by evaporation,and that under the mid-film was medium.The variant hourly of surface soil EC was intense.The hourly relative amplitude of variation under the narrow row was largest and the hourly absolute amplitude of variation was largest under the inter-films.The amplitude of variation decreases with the increasing of depth.The soil EC was significantly affected by soil temperature under film-mulched drip irrigation and their relationship was complicated.The correlation coefficients were different at different time and depth.The correlation between soil EC and soil temperature was remarkably positive under the inter-film.It was unremarkably positive under the narrow row.However,this correlation under the mid-film was unremarkably positive in the morning and was remarkable negative in the afternoon.