The objective of this study was to explore the spatial-temporal variability of soil organic matter(SOM)and its influencing factors. Based on the data of 168 sample points collected in 1982 from the Second Soil Survey and 213 soil sample points collected in 2017 of the Xiaohe River basin in the eastern Loess Plateau, the spatial and temporal variation of soil organic matter in the drainage basin in the last 35 years and the influencing factors were analyzed by statistical and geostatistics methods. The results showed that from 1982 to 2017, the mean value of soil organic matter in cultivated soil increased from 11.06 g·kg^-1 to 15.69 g·kg^-1, and the amplification reached 41.86%. In the recent 35 years, the organic matter in the farmland of the Xiaohe River basin had an increasing trend, and the spatial distribution in creased gradually from the central part to the surrounding area. From the year of the second soil census to 2017, the organic matter content of the soil in the ploughed layer showed the rule of gradually accumulated from lower level to higher level. Among them, the land area of soil organic matter content >20 g·kg^-1 and 15~20 g·kg^-1 increased from zero to 0.74% and 43.72% of the total area of the river basin respectively, the land area of 10~15 g·kg^-1 decreased the most, and it reached 29.93%, 6~10 g·kg^-1 decreased from 13.82% to 1.57%, and <6 g·kg^-1 decreased from something to nothing. Soil parent material, topography change, planting structure and fertilization are the main factors that affect the temporal and spatial differentiation of soil organic matter. Human beings show an increasing trend of soil nutri ent intervention, and we should be paid attention to the regional management of soil fertilizer to ensure the sustainable development of the whole agricultural watershed.
Journal of Agricultural Resources and Environment
soil organic matter
Xiaohe River basin