THE SPATIAL PATTERN CHARACTERISTICS OF SOIL NUTRIENTS AT THE FIELD SCALE

摘要

This paper took the wheat field of typical alluvial soil area as the research site,aimed to explore the spatial pattern of the soil nutrients, such as soil available potassium, soil available phosphorus, soil organic matter (SOM) and soil alkali hydrolysable nitrogen. With the help of DGPS, a total of 104 topsoil(0-20cm) samples were collected. Based on classical statistics, research results indicated the average content of soil available potassium was 287.476g/kg, the high value was 483.433g/kg, the low value was 119.435g/kg. The average content of soil available phosphorus was 54.228g/kg, the high value was 293.13g/kg, the low value was 18.77g/kg. The average content of SOM was 36.901g/kg, the high value was 47.420g/kg, the low value was 21.110g/kg. The average content of soil alkali hydrolysable nitrogen was 66.444g/kg, the high value was 166.474g/kg, the low value was 29.846g/kg. Geostatistical analysis, combined with geographical information system(GIS), the range, nugget and sill of soil nutrients characteristics were calculated, semivariogram model was established, ordinary kriging was applied, and the spatial distributing map of soil nutrients was drawn. It is shown that the semivariogram structures of the soil nutrients was spherical, the ratio of nugget/sill of soil available potassium, SOM, soil alkali hydrolysable nitrogen was 0.399, 0.746 and 0.696, respectively, which belonged to the middle intensity, the ratio of nugget/sill of soil available phosphorus was 0.759, which belonged to the low intensity. Spatial variation of soil available potassium was mainly caused by structural factors(parent material, terrain, climate, water table etc.), the structure variability of it took 60.1% of the total variability, the spatial variation of soil available phosphorus, SOM and soil alkaline hydrolysis nitrogen were mainly caused by random factors(fertilization, environmental pollution, cultivation measures, management etc.), the random variability of them took 75.9%, 74.6%, 69.6% of the total variability, respectively, the spatial correlation distance of SOM, soil alkaline hydrolysis nitrogen, soil available potassium and soil available phosphorus was 44.898 m, 45.191 m, 57.691 m and 23.328 m, respectively.