Relationship Between Total Nitrogen and Topographic, Parent Material in Typical Subtropical Region——A case study in Xingguo County, Jiangxi Province

Spatial distributions of total nitrogen in soils are difficult to estimate because of their inherent spatial variability and because of lack of ample data.Based on 151 sample data, spatial distribution characteristic of total nitrogen was studied.Correlations between total nitrogen and topographic factors were analysed.Regression model was established through linear regression analysis.The result showed:mean content of total nitrogen was 1.06 g/kg in topsoil.Sandstone and shale showed the lowest average TN content (0.88 g/kg soil),phyllite showed the highest average TN content (1.35 g/kg soil) .TN content between 0.5 g/kg and 1.0 g/kg has the biggest area (1 583.7 km~2) from spatial distribution,TN content exceeding 2.0 g/kg has the smallest area (126.7 km~2).Aspect among topographic variables had an important influence on TN content.The correlations with TN content and parent rocks, elevation, aspect were positively significant (P0.05),The correlation with slope and TN content was no significant.Spatial distribution of TN content could be forecasted by using linear regression model.