废弃盐田复垦利用后土壤盐分与有机质含量空间变异特征

针对目前莱州湾南岸废弃盐田复垦过程中存在的土壤盐碱、瘠薄等障碍问题,以该区两个典型复垦地块为研究对象,综合运用经典统计学和地质统计学的克立格法,研究不同复垦年限下各层土壤盐分和表层土壤有机质的空间变异性,对二者进行相关性分析,并绘制了各土层盐分和表层土壤有机质含量的空间分布图。结果表明:两个区域各层土壤含盐量较高,均超过1g/kg;受复垦年限、土地平整水平和施肥等人为复垦措施影响,二区土壤含盐量明显低于一区;两个区域土壤有机质含量普遍较低,其中一区为4.37g/kg,二区为3.66g/kg;两个区域各层土壤含盐量和表层土壤有机质变异系数在32.79%—83.83%之间,在水平方向上呈中等变异强度;相关性分析结果表明各层土壤含盐量与有机质含量均呈极显著负相关;各土层土壤含盐量和有机质含量的块基比均小于25%,表明二者具有强烈的空间相关性;空间自相关距离最小为440m,超过采样间距(最小为160m),表明采样间距设置合理;Kriging插值结果表明两个区域土壤含盐量和有机质含量呈条带状分布;一区土壤含盐量以中部为高值区逐渐向南北部降低,二区土壤含盐量则以东南部最低,逐渐向西北部高值区过渡;一区土壤有机质含量表现为中部低南北部较高,二区则为东南部最高,中北部含量较低。研究结果为后期高含盐量的水盐运移模拟研究提供初步论证,也为盐田复垦区盐渍土的合理分区,改良利用和科学管理提供了技术支撑。

Spatial variation of soil salinity and organic matter under reclamation in an abandoned salt pan

Soil salinization and low fertility are problems associated with the abandoned salt pan in the southern coastal area of Laizhou Bay. Therefore, two typical reclamation areas were the research focus of the present study, which used classical statistics and geostatistical Kriging interpolation methods to evaluate the spatial variation of soil salinity and organic matter of typical parcels at different reclamation years. The correlation between soil salinity and organic matter was analyzed, and the spatial distribution maps of soil salinity in the different soil layers and organic matter contents of the surface layer were also evaluated. The results indicated there was high soil salinity in both reclamation areas, and the levels of both areas were higher than 1g/kg. Due to the effect of reclamation years, land leveling, irrigation, and tillage methods, the soil salinity in area two was evidently lower than that in area one. Low organic matter content was also found in the two areas, which was 4.37 and 3.66g/kg in areas one and two, respectively. Both the soil salinity and organic matter showed moderate spatial variability in the horizontal direction, and the variation coefficient was in the range of 32.79%-83.83%. The correlation analysis results indicated a significant negative correlation between the soil salinity and organic matter in all soil layers; the nugget/sill ratio was less than 25% indicating a strong spatial correlation between the two parameters. The minimum autocorrelation distance was 440m, which was longer than the sampling intervals (minimum value was 160m), indicating that the sampling intervals were rational. The spatial distribution maps of the soil salinity and organic matter content obtained using the Kriging interpolation showed an apparent strip style. In area one, the soil salinity gradually reduced from the central region to the northern and southern regions. In area two, the soil salinity had the lowest value in the southeast and gradually shifted to the high-value area in the northwest. The organic matter content was lower in the central area than that in the southern and northern area in area one. However, the highest organic matter content was observed in the southeast region, whereas lower values were found in the central and northern regions in area two. The research results could provide a theoretical basis and technical support for the rational partitioning, amelioration, and utilization, as well as scientific management of saline soils in salt pan reclamation areas.