Abstract: The variation of soil organic matter plays an important role in soil fertility evaluation. In this paper, the variability of soil organic matter in space is analyzed by using geographic information system software. Soil samples were collected from Kenli County, a typical district in the Yellow River Delta. Results show that the content of soil organic matter in the study area is low, with an average value of 11.37 g/kg. The coefficient of variation is 27.19%, indicating that the total variance of intensity is not big. Soil organic matter is relatively large in content in the east part of Kenli County and distributes in a narrow strip as the east Kenli is adjacent to the mouth of the Yellow River, resulting in the deposition of soil organic matter; whereas in the south part where land use types are beach and sand, the content of soil organic matter is relatively low, and the accumulation of soil organic matter is not obvious. The study area is located in the downstream of flat river delta with enough farmland infrastructure facilities, strong drainage capacity, good irrigation conditions, as well as abundant water sources, which have little effect on the spatial variance of soil organic matter. Soil type, soil parent material, and topography have no significant effect on soil organic matter in the study area either. The effects of other factors on the spatial variability of soil organic matter content need further research.

Key words: Yellow River Delta, soil organic matter, spatial variability, Kenli County, GIS software, influential factors