干旱区农田灌溉前后土壤水盐时空变异性研究

Spatial and temporal variations in soil water and salt in arid areas before and after irrigation

通过田间土壤剖面取样,测定了新疆奇台县干旱区农田灌溉前、灌溉后1周和3周土壤水盐的时空变异特征。结果表明:灌溉前,剖面各层土壤含水量较低(15.25%～16.70%),且呈中等(偏弱)变异性;剖面上部(40 cm以上)土壤盐分呈强变异性,而下部为中等(偏强)变异性。灌溉后1周,除0～20 cm(弱变异性)外,其他土层水分及剖面下部盐分变异性未变,但变异系数均减小,上部土壤盐分转为中等(偏强)变异性;剖面平均土壤含水量升高10.51%,脱盐率达8.94%,其中,表层(0～20 cm)土壤水分增加率(118.48%)及脱盐率(20.86%)最大,底层(100～120 cm)水分增加率(40.54%)及脱盐率(-6.93%)最小。灌溉后3周与1周相比,各层(除80～100 cm土层)水分及盐分的变异性保持不变,但水分的变异系数增大,而盐分的变异系数减小;剖面平均含水量减少5.20%,表层(0～20 cm)失水率(36.47%)最大,80～100 cm失水率(7.31%)最小;表层土壤积盐率(4.55%)约为20～40 cm土层的12倍;而40 cm土层以下仍处于脱盐阶段,40～80 cm土壤脱盐率减小,80～120 cm土层脱盐率(9.03%)增大。

Spatial and temporal variations in soil water and salt contents of arid farmlands in Qitai County,Xinjiang was investigated before and one week,3 weeks after irrigation through profiles sampling.The results showed low soil water contents（15.25%～16.70%） in all soil layers before irrigation,with moderate to weak spatial variability.Salt content in the upper 40 cm soil layer was strongly variable,while that in the lower soil layer was moderately variable.One week after irrigation,soil water and salt contents in the soil layers（except for the 0～20 cm soil layer with weak variability） remained unchanged,but their coefficients of variation dropped.Salt content variability in the upper soil layer changed to medium and strong.Average water content in the profiles increased by 10.51%,with a desalting rate of 8.94%.The rates of water increase（118.48%） and desalting（20.86%） in the 0～20 cm soil profile were the highest.On the other hand,the rates of water increase（40.54%） and desalting（？6.93%） were lowest in the 100～120 cm soil layer.Compared with the one week post-irrigation condition,variation in water and salt contents in the soil layers（except for the 80～100 cm soil layer） remained unchanged three week after irrigation.However,the coefficient of variation for water content increased while that for salt decreased.Average water content along the soil profile decreased by 5.20%.The rate of water loss（36.47%） in the surface 0～20 cm soil layer was highest while that（7.31%） in the 80～100 cm soil layer was lowest.The rate of salt accumulation（4.55%） in the surface soil was about 12 times that in the 20～40 cm soil layer.While desalting still occurred below the 40 cm soil layer,that in the 40～80 cm soil profile decreased.Desalting rate（9.03%） in the 80～120 cm soil layer increased.