Effects of Soil Parent Material and Farmland Utilization on Nitrogen Distribution in Soil Profile in Chengdu Plain
Understanding the profile distribution characteristics of soil nitrogen and its influencing factors in the farmland is essential for regional nitrogen fertilizer management and control of non-point source nitrogen pollution.Based on 1 356 samples from 173 soil profiles on the Chengdu Plain,this study analyzed the spatial variation characteristics of soil nitrogen in farmland soil profile using geostatistics and variance analysis and identified the effects of agricultural land use types and soil parent materials on the nitrogen distribution in soil profile.The results show that the contents of total nitrogen(TN)and available nitrogen(AN)decreased significantly from 1.91 g·kg-1 and 138.48 mg·kg-1 to 0.55 g·kg-1 and 25.39 mg·kg-1,respectively,in the 0-100 cm soil layer with the increase in soil depth.Spatially,the contents of TN and AN in each soil layer had a similar spatial distribution pattern,which showed an increasing trend from the central to the north-east and southwest.There was no significant difference in the contents of TN and AN of each soil layer between rice-vegeta-ble rotation land and rice-wheat/rapeseed rotation land,while the contents of TN and AN in the surface layer(0-20 cm)of afforested land were 11.23%-15.78%lower than those of the other two land uses(P<0.05).Compared with soils formed from Q4 gray alluvium,soils formed from Q3 old alluvium had 1.12-1.19 times of TN and AN content in 0-40 cm soil layer(P<0.05)and 0.89 times of TN content in>60-100 cm soil layer(P<0.05),while the contents of TN and AN in the 0-40 cm soil layer of soils formed from Q4 gray-brown alluvium were 1.14-1.21 times as those in the Q4 gray alluvium(P<0.05).There were no significant differences in the contents of TN and AN under different land uses in each layer of Q3 old alluvium developed soil(P>0.05).For afforested land,soils formed from Q4 grey alluvium and Q4 grey-brown alluvium in afforested land had lower TN and AN content in the topsoil than the other two land use types,but had higher TN and AN content below the>20-40 cm soil layer.The above results suggest that the profile distribution charac-teristics of soil nitrogen are affected by agricultural land use types and such effects are controlled by soil parent material.
soil nitrogensoil profilespatial distributionagricultural land use modesoil parent material
万方数据
维普
