盐碱地土壤养分的空间变异及合理取样密度研究

Spatial Variability of Soil Nutrients and Salinity in Saline-alkali Land and Determination of Reasonable Sampling Density

本研究以东营市河口区新户土地开发项目二期为研究区,运用经典统计法和地统计分析相结合的方法,对土壤有机质、速效磷、速效钾、碱解氮等养分以及土壤全盐的空间变异性质进行研究,并对不同采样密度下有机质的空间插值结果进行分析比较,用均方根误差和相关系数检验不同密度下的插值精度,以确定盐碱地有机质的合理取样密度。结果表明,研究区速效钾的变异系数为18.4%,属于低等程度的变异;有机质、碱解氮、速效磷、土壤全盐的变异系数在57.4%~76.9%之间,属中等程度变异。研究区的各种土壤属性均具有较好的空间结构,表现出一定的空间自相关性。有机质和速效钾的空间变异性主要影响因素与成土母质、土壤类型、气候条件等有关,而碱解氮、速效磷、土壤全盐的空间变异性与耕作方式及农业生产中施肥等有关。随着采样点密度的增加,克里格插值精度提高,适当减小样点密度可以满足插值分析的需要,充分考虑土壤养分空间变异评价的精度分析,确定研究区土壤有机质合理取样数为111个,合理取样单元为48 hm^2,合理取样间距为692 m。

Spatial variations of soil organic matter, available nitrogen, phosphorus, potassium alkali-hydro nitrogen and soil salinity were discussed by the means of classical statistics and geostatistics in Land Development Project Phase II of Xinhu Town in Hekou District, Dongying City. Spatial interpolation results of organic matter under different sampling density were analyzed and compared and the interpolation accuracy was tested with the root mean square error and correlation coefficient, in order to determine the appropriate sampling density of organic matter in saline land. The results showed that, the coefficient variation of available K was 18.4%, which belonged to the low degree of variation. The coefficient variations of organic matter, alkali-hydro nitrogen, available phosphorus, soil salt were between 57.4% 76.9%, which belonged to the moderate variation. All the soil properties of the study area had good spatial structure, and showed some spatial autocorrelation.The spatial variability of organic matter and available potassium was related with the soil parent material, soil type and climate conditions whereas the spatial variability of alkali-hydro nitrogen, available phosphorus, soil salt was related with the tillage and agricultural fertilizer practices. As the sampling density increaseed, Kriging interpolation accuracy was improved. Proper reduction of the sample point density could meet the needs of the interpolation analysis, The accuracy analysis of spatial variability of soil nutrients was considered, and the reasonable sampling number of soil organic matter in the study area was 111, with the reasonable sampling interval of 48 hmz, and the reasonable sampling unit of 692 m.