Abstract: As the important sources of nutrients for plants and the ecological factors guaranteeing ecosystem health, the contents and stoichiometry of soil carbon, nitrogen and phosphorus have important impacts on primary productivity. Understanding the spatial variability and driving forces of soil C, N and P content and stoichiometry is significant to soil nutrient management and sustainable land use. We analyzed the spatial variability and driving factors of soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP) contents and stoichiometric characteristics in Sanyanjing catchment on the eastern Loess Plateau, using classical statistics with geostatistics methods. Results showed that: (1) The mean contents of SOC, TN and TP were 3.97, 0.83 and 0.6 g·kg^-1, and the mean value of C∶N, C∶P and N∶P was 4.73, 6.02 and 1.26, respectively. There were moderate spatial variation of soil C, N and P contents and stoichiometry. (2) Land use types and landform types had significant effects on SOC and TN, with higher values in forest and grassland than in terrace and abandoned farmland, and higher at the ridge than at the ravine. TP was mainly affected by land use type, with higher value in terrace than the other three land use types. Land use type had a consistent effect on soil C∶N, C∶P and N∶P, with lowest value in the terrace. Moreover, C∶N was significantly affected by slope gradient and landform type, and C∶P by slope gradient and N∶P by elevation. (3) Predicted maps by regression kriging method demonstrated the effects of environmental factors on ecological stoichiometry of soil C, N and P with better prediction accuracy. There were differences for the spatial patterns of ecological stoichiometry across the catchment. Different approaches of organic dry farming, balanced fertilization, soil and water conservation, and reasonable spatial allocation are beneficial to improving the balance of soil C, N and P in the study area.

Key words: biochar, soil water upward movement, particle size, evaporation.