Spatial Characteristics Of Soil Nitrification And Denitrification Potential In Lakeshore Zones Covered By Two Plants

The lakeshore zone lies between terrestrial ecosystem and aquatic ecosystem,which can slow down the input of materials into the terrestrial system and is the most direct and effective natural barrier to control the water quality of lakes.The spatial heterogeneity of the soil and the difference in vegetation cover will affect the nitrification and denitrification process of the soil in the lakeshore zone,but the spatial characteristics and interaction of the physical and chemical properties of the soil on the conversion of nitrogen in the lakeshore zone are not clear.In view of this problem,this study collected soil samples at selected sampling points in the cover area of herbaceous and arborvitae plants on the shore of Yezhi Lake,and further carried out nitrification and denitrification potential culture experiments of soil samples at different depths.The basic physicochemical properties,nitrification and denitrification potential of different samples were analyzed,and the spatial characteristics and variations of soil nitrification and denitrification potentials under the interaction of different factors were studied.The main conclusions of this study are as follows:（1）There were significant differences in the nitrification potential of the soil in the lakeshore zone under herbaceous and arborvitae vegetation cover（P<0.05）.In winter,the soil nitrification rate of the lakeshore zone covered by herbaceous vegetation was0.24%～53.17%,and the net nitrification rate was 0.06～31.20 mg/kg/d.The soil nitrification rate of the lakeshore zone covered by arborvitae vegetation was0.46%～17.24%,and the net nitrification rate was 0.16～5.54 mg/kg/d.In summer,the soil nitrification rate of the lakeshore zone covered by herbaceous vegetation was 0.21%～3868%,net nitrification rate was 0.04～14.99 mg/kg/d,the soil nitrification rate of the lakeshore zone covered by arborvitae vegetation was 3.07%～15.48%,net nitrification rate was 1.09～5.12 mg/kg/d.The nitrification potential of the lakeshore soil under herbaceous vegetation was higher than that under arbor vegetation.The nitrification potential of the lakeshore soil in winter was higher than that in summer.（2）There were significant spatial differences in the nitrification potential of soils in the lakeshore zone,and the interaction between environmental factors had a significant impact on the nitrification potential of soils（P<0.05）.In winter,among the various factors of soil covered by herbaceous vegetation,the contribution rate of depth² was the largest of41.96%,among the factors covered by arborvitae vegetation,the TC×p H contribution rate was the largest of 47.71%.In summer,among the various factors of soil covered by herbaceous vegetation,the contribution rate of depth×p H was the largest of 48.12%,among the factors covered by arborvitae vegetation,the NO₃^--N×NH₄⁺-N was the largest of 45.95%.（3）There were significant differences in the denitrification potential of the lakeshore zone under herbaceous and arborvitae vegetation cover（P<0.05）.In winter,the soil denitrification enzyme activity of the lakeshore zone covered by herbaceous vegetation was 0.02～0.94 mg/kg/h,and the net denitrification rate was 0.30～1.46 mg/kg/h.The soil denitrification enzyme activity of the lakeshore zone covered by arborvitae vegetation was 0.15～1.96 mg/kg/h,and the net denitrification rate was 0.25～1.73 mg/kg/h.In summer,the soil denitrification enzyme activity of the lakeshore zone covered by herbaceous vegetation was 0.09～0.88 mg/kg/h,and the net denitrification rate was0.28～1.28 mg/kg/h.The soil denitrification enzyme activity of the lakeshore zone covered by arborvitae vegetation was 0.23～1.24 mg/kg/h,and the net denitrification rate was0.30～1.25 mg/kg/h.The denitrification potential of the lakeshore soil under herbaceous vegetation was lower than that under arbor vegetation.The nitrification potential of the lakeshore soil in winter was higher than that in summer.（4）There were significant spatial differences in the denitrification potential of soils in the lakeshore zone,and the interaction between environmental factors had a significant impact on the denitrification potential of soils（P<0.05）.In winter,among the various factors of soil covered by herbaceous vegetation,the contribution rate of depth² was the largest of 21.67%,among the factors covered by arborvitae vegetation,the TC²contribution rate was the largest of 49.27%.In summer,among the various factors of soil covered by herbaceous vegetation,the contribution rate of TC was the largest of 48.24%,among the factors covered by arborvitae vegetation,the depth×TC was the largest of45.95%.The results show that the nitrification and denitrification potential of the lakeshore zone under different vegetation cover have significant spatial heterogeneity,which provides a reference for the targeted use of the lakeshore zone for non-point source nitrogen interception.