Nitrogen And Phosphorus Forms And Loss Risk In A Typical Artificial Woodland North Of Huaibei Plain

By a certain artificial woodland in Gucheng town,Huaiyuan County,Bengbu City in Huaihe River Basin as the main research object,75 sampling points are arranged to collect soil samples,47 woodland soil samples,16 woodland drain soil samples,12 farmland soil samples among them.Based on the test,we analyzed content and spatial distribution of nitrogen,phosphorus and organic matter,the bioavailability of nitrogen and phosphorus in soil;tested the correlation and difference of nitrogen and phosphorus content,organic matter and pH value through the principle of correlation and difference analysis;assessment of nitrogen and phosphorus loss in woodland soil by nitrogen and phosphorus index and evaluation of soil phosphorus leaching risk by determining the critical value of soil phosphorus leaching.The main research results are summarized as follows:?1?The average concentrations of TN and TP in woodland are 1818.42 mg·kg^-1 and524.384 mg·kg^-1.The range of organic matter is 2.45%⁸.86% and pH values distributed in 4.26⁸.60,mean value of pH is 6.70,the woodland soil are neutral roughly.Compared with other types of land,the content of nitrogen and phosphorus,organic matter and pH level are between woodland drain and farmland roughly.?2?The average content of bioavailability of nitrogen and phosphorus in woodland soil are 204.50 mg·kg^-1and 126.826 mg·kg^-1,accounted for 11.68% and 25.73% of the TN and TP.The average content of bioavailability of nitrogen and phosphorus in high-forest are highest inside woodland soil;the result of sort the average content bioavailability of nitrogen and phosphorus in the whole study area are farmland>woodland drain>woodland and woodland>farmland>woodland drain.?3?The correlation analysis showed,in woodland soil,there are no correlation between the three nitrogen forms,and significant correlation between TP and phosphorus forms;between the forms of nitrogen and phosphorus and organic matter,pH value is certain correlation;The correlation between the pollution indexed of the woodland soil is better than that of the woodland drain and farmland.According to the result of difference analysis,the contents of nitrate,calcium-phosphorus and organic matter are significantly different between woodland and farmland;the contents of organic matter are significantly different between woodland and woodland drain,between the three groups,there is a significant difference in pH value.?4?The woodland soil nitrogen and phosphorus index are 2.79 and 3.48,nitrogen loss is mainly medium risk and phosphorus loss is mainly low risk.The rate of Fe/Al-P enrichment is higher and the rate of IP enrichment is lower in study area.The critical values of Olsen-P for three types of land are 64.909 mg·kg^-1,33.753 mg·kg^-1 and 37.423mg·kg^-1,the percentage of soil samples exceeding the critical value in each total number of samples are 23.4%,31.3% and 41.67%,average relative risk coefficient of three types of land are 0.173?0.426?0.274,the relative risk coefficient of woodland is lower than woodland drain and farmland.Therefore,phosphorus leaching risk level is not high in woodland soil.