渭北地区农田土壤物理性质对土壤剖面盐分的影响

Influence of Soil Physical Properties on Salt Content in Soil Profile of Farmland in Weibei Region

通过网格布点法对渭北地区农田土壤进行采样分析,研究了土壤团聚体、土壤容重、土壤质地对土壤剖面盐分的影响。结果表明:(1)研究区轻度盐渍化面积占46.56%,中度盐渍化占23.01%,渭北地区农田土壤盐渍化程度总体不严重但存在较大潜在风险。(2)各层土壤水稳性团聚体与含盐量呈负相关,容重与含盐量的关系因盐渍化程度不同而在各土层表现出不同的正负效应,土壤质地与含盐量仅在0—20cm土层存在显著相关性。(3)土壤物理性质对含盐量的异位影响与含盐量水平有关。当土壤含盐量<1g/kg时,40—60cm容重与20—40cm含盐量为幂函数关系,且呈递增趋势;土壤含盐量在2~4g/kg时,20—40cm容重与0—20cm含盐量为一次函数关系,且呈递增趋势;当含盐量>2g/kg时,0—20cm容重与20—40cm含盐量为一次函数关系,且呈递减趋势;含盐量>2g/kg时,水稳性团聚体与含盐量呈显著线性负相关。

Soil salinization is an important type of soil degradation,which seriously restricts the development of agricultural production.Weibei region is the second granary of Shaanxi province.However,due to the higher groundwater level and salinity,the region is suffering from soil salinization,big waterlogging disasters,and high soil compaction for a long time.In order to analyze the influences of soil physical properties,such as water-stable aggregate,soil bulk density and soil texture on salt distribution in soil profile,soil samples were collected from typical farmland in Weibei region through 10km×10km mesh point method.The results showed that：（1）Soil salinization in Weibei region was not very serious but at a high potential risk.The proportion of mild salinized soil accounted for 46.56%,while the moderate salinized soil only23.01%.（2）Soil salt content increased with the increasing of soil depths in the profile,which indicated that the soil salt would be accumulated to the topsoil with water evaporation in improper managements.Strong negative correlation was observed between water-stable aggregate and soil salt content in the studied profiles.While,the correlation between soil bulk density and salt content varied with the degree of soil salinization.The influence of water-stable aggregate on salt content in topsoil was stronger than that of soil bulk density.However,significant correlation occurred between soil texture and salt content only in 0—20cm soil layer.（3）The effect of soil physical properties on salt content was not only found in the same soil layers but also in different soil layers.Namely,the ectopic impact was found in the influence of soil physical properties on salt content,and this impact was related to the degree of soil salinization.When salt content was lower than 1g/kg,apower function relationship was observed between soil bulk density in 40—60cm layer and saltcontent in 20—40cm layer.An increasing function was observed between soil bulk density in 20—40cm layer and salt content in 0—20cm layer when salt content ranged from 2g/kg to 4g/kg.However,when salt content was higher than 2g/kg,a decreasing function would be found between soil bulk density in 0—20cm layer and salt content in 20—40cm layer.A decreasing function was observed between water-stable aggregate and salt content,especially when salt content was higher than 2g/kg.