Soil Properties With Grass Cover In Carya Cathayensis

This study focused on Carya cathayensis forest covering with White Clover （Trifolium repens L）,perennial ryegrass（Lolium Perenne L）, rape（Brassica campestris L）, milk vetch（Astragalus sinicus L.）,natural weeds and cleaning tillage was used as the control（CK）. The annual dynamic change rules ofsoil nutrients and soil temperature and humidity with different green cover were measured. Theinteraction between green cover and soil properties was discussed for providing a theoretical basis insoil management of Carya cathayensis forest. The main results were as follows:（1） Effect of green cover on soil temperature improved greatly, which decreased soil temperaturein summer and increased that in winter. In January,0-10cm layer soil temperature with grass was higherthan that of cleaning tillage, yet10-20cm layer change was not obvious and the effects of White Cloverand Perennial Ryegrass were significantly; In July,0-10cm soil temperature decreased significantlywith grass, especially White Clover and natural weeds. Green cover enhanced soil surface humidity.The effect on soil surface humidity of White Clover and natural weeds better than Rape in the wholegrowing process.（2） The trend of changes of water content at the two layers of soil in different green cover wasbasically identical. Change of surface layer was higher than that of sub-surface layer. Soil wartercontent fluctuated between19.64%and39.47%and changed significantly that was due to the rainfall.The difference between green cover treatment and cleaning tillage treatment was remarkably in July.The different green cover treatments had different effects in different months due to their differentbiological traits.（3） Grass cover treatment increased soil content organic matter and percent conversion of soilnutrient which leaded to soil organic, total N, total P, total Ca and available K, Mn and Zn andexchangeable K, Ca were higher than that of cleaning tillage treatment. However in the grass covertreatments both Hickory and grass had a big demand of nutrient at0-20cm layer that soil total K, totalFe, total Mn, total Mg, available Ca and exchangeable Mg didn’t change a lot.（4） Soil enzymatic activity was raised markedly with interplanting green cover. Different grasscover had different effects on soil enzymatic activity in different seasons. In the experiment, leguminous plants and natural weeds improved significantly the activity of Urease, Catalase and Invertase. WhiteCover and natural weeds had a good effect on increasing enzymatic activity.（5） There was a positive correlation between soil nutrient content and soil enzymatic activity.Sucrase activity was proved to be significantly correlated with pH, total N, available N, total P and K.Urease activity was proved to be significantly or very significantly correlated with pH, water content,organic matter, total N and available N, but with P and K there wasn’t a significant correlation. Catalaseactivity was proved to be significantly （P>0.01） correlated with water content, organic matter, total Nand available N and a significant （P>0.05）) correlation with available P and total K, but with pH, total Pand total K, it didn’t reach a level of significance. The activities of sucrase, urease and catalase werepositive significantly correlated with exchangeable K⁺、Ca²⁺、Mg²⁺and soil available Mn, Zn, but anegative correlation with available Fe.