河套灌区典型示范区土壤盐分和有机质空间变异特征

Spatial variation characteristics of soil salinity and organic matter in typical demonstration area of Hetao irrigation area

为探明河套灌区盐渍化土壤盐分和有机质含量分布规律,选取巴彦淖尔市五原县盐渍化土壤典型区域作为研究区,采用区域土壤信息定点监测,选取149个采样点,获得各土层土壤样本,并结合经典统计学、地统计学、空间插值等方法,研究盐渍化土壤盐分和有机质含量空间变异特征。结果表明:随着土层深度的增加,土壤有机质含量与土壤盐分含量的相关性逐渐增加,在深层土壤间盐分对有机质含量的影响大于表层,且在40-60 cm影响最显著。研究区各层土壤盐分的最优半方差函数模型为球状模型,土壤有机质的最优半方差函数模型为高斯模型。规模化盐碱地改良后,0-20、20-40、40-60 cm土壤盐分结构比(表示随机因素引起的空间变异占系统总变异的比例)上升2.35、6.72、1.94个百分点,0-20、20-40 cm土壤有机质结构比分别上升3.54、3.93个百分点,土壤盐分和有机质结构比整体较改良前呈上升趋势,结构性增强,空间相关性增强,垂直方向上土壤盐分变异性强于有机质变异性。改良期内土壤盐分含量平均降幅为0.574g/kg,土壤有机质含量平均增幅为0.195 g/kg,耕层土壤盐渍化程度减弱,各层土壤有机质含量增加,作物生长安全区增大,研究区土壤环境显著改善。土壤盐分高值区(>6 g/kg)多位于地下水浅埋区的中部和东南部区域,改良后,研究区中部土壤盐分集聚特征仍十分显著,存在盐渍化加剧的风险,仍是盐碱地改良防治重点的区域。

In order to explore the distribution characteristic of salinized soil salinity and organic matter content in the Hetao irrigation area,a typical area of salinized soil in Wuyuan County,Bayannaoer City was selected as the research area,regional soil information was used for site-specific monitoring,and 149 sampling points were collected for different profiles.The spatial variability of salinized soil salinity and organic matter content were studied by using classical statistics,geostatistics,spatial interpolation and other methods.The results showed that:With the increase of soil depth,the correlation between soil organic matter content and soil salinity content increased gradually.The influence of salinity on the organic matter content in the deeper soil layer was greater than that of the surface layer,and the effect was the most significant at the depth of 40~60cm.The optimal semi-variance function model of each layer of soil salt in the study area was the Spherical model,and the optimal semi-variance function model of the soil organic matter was the Gaussian model.After the large-scale improvement of saline-alkali land,the soil salt structure ratio(representing the proportion of the spatial variation caused by random factors in the total system variation)of 0~20,20~40,40~60 cm layer increased by 2.35,6.72,1.94 percentage point,and the soil organic matter structure ratio of 0~20 and 20~40 cm increased by 3.54,3.93 percentage point,respectively,the structure ratio of soil salinity and organic matter showed an upward trend compared with that before the improvement.The variability of soil salinity in the vertical direction was stronger than that of organic matter.During the improvement period,the average soil salinity content decreased by 0.574 g/kg,and the average soil organic matter content increased by 0.195 g/kg;The soil salinization of the cultivated layer was weakened,the organic matter content of each layer increased,and the crop growth safety zone increased;The soil environment in the district had improved significantly.Areas with high soil salinity(>6g/kg)are mostly located in the middle and southeast of the shallow groundwater area.After improvement,the characteristics of soil salt accumulation in the middle of the study area are still very significant,and there is a risk of increasing salinization,which is still a key area for improvement and prevention of saline-alkali soil.