关键词: 土壤有机质, 碱解氮, 空间变异, 影响因素, 川中丘陵区

Abstract: This paper analyzed the spatial variability characteristics and its influencing factors of soil organic matter (OM) and alkaline nitrogen (AN) by the method of GIS combined with geostatistics based on 441 topsoil sample data collected in central hilly area of Daying County of Sichuan Province. The results showed that the mean value of OM and AN in study areas was 15.22 g/kg and 76.75 mg/kg, respectively, both of them were generally low. As for the spatial pattern, soil OM played a tendency with values higher in north, lower in south and the lowest in central. While, AN showed no obvious distribution trend, the low value zone just located in the center of study areas. The results of  semivariance analysis showed that the value of nugget to sill for soil OM and AN was 83.55 and 51.32, respectively, indicating OM spatial variability was affected by random factors like tillage and fertilization, while AN was affected by random and structural factorslike climate, soil type and topography. The analysis of affecting factors indicated that topography, soil type and cropping system were the important factors affecting the spatial variability of soil OM and AN, while parent material had no significant impact on  OM and AN contents. These results suggested that we should fully consider the influencing factors on the spatial variability of soil OM and AN during the process of land use and fertilization.

Key words: soil organic matter, alkaline nitrogen, spatial variability, influencing factor, hilly areas of central Sichuan