Profile Characteristics Of Calcium,magnesium And Manganese In Main Soil Types In Guizhou Mountainous Area

This paper selects the two main soil types of lime soil and yellow soil in Guizhou karst area as the research object,and combines the litter-soil-parent rock layer under different land use to obtain the distribution of calcium,magnesium and manganese,revealing the calcium and magnesium profiles of different types of soil The spatial variation characteristics of manganese form and the law of migration and transformation.Provide a certain theoretical basis and support for the study of soil and water conservation,environmental restoration,and element migration in Guizhou mountainous areas.The main conclusions of this paper are as follows:(1)The content of CaO in cultivated land and returning farmland to grassland in lime soil profile increases as the soil layer deepens.The overall change of available calcium and acid-soluble calcium is surface accumulation,and the overall organic combined calcium content is surface layer> bottom layer.The soil CaO content of cultivated land under the same level is relatively high,and the highest content of water-soluble calcium,exchangeable calcium,and organically bound calcium are found in forest-grass intercropping land.The acid-soluble calcium on the yellow soil profile tends to increase with the deepening of the soil layer,and the remaining calcium forms are better accumulated in the surface layer of waste grassland and shrubs.(2)The content of MgO and acid-soluble magnesium in the lime soil profile has the risk of leaching,while the effective magnesium and organically bound magnesium remain more on the surface.At the same level,the highest available magnesium content is in forest-grass intercropping land,and acid-soluble magnesium and organically bound magnesium are higher in shrubland.On the yellow soil profile,the contents of MgO and exchanged magnesium are the largest in the surface layer.The other forms of magnesium change more complicatedly on the profile.The content of available magnesium,acid-soluble magnesium,and organically bound magnesium is at a high level in cultivated land and returning farmland to grassland.(3)MnO and weakly acidic manganese on the lime soil profile are at risk of leaching,while water-soluble manganese,oxidizable manganese,and reducible manganese are aggregated on the surface.The content of MnO and oxidizable manganese in the same soil layer is higher in the wasteland,the content of water-soluble manganese and weak acid manganese is higher in the forest-grass intercropping environment,and the reducible manganese is the highest in cultivated soil.In the yellow soil profile,except for water-soluble manganese which is accumulated on the surface,all other manganese forms have leached.On the same soil layer,the content of MnO and reducible manganese is higher in the wasteland,the content of water-soluble manganese and weak acid manganese is higher in the forest land,and the oxidizable manganese is higher in the shrubland soil.(4)Regardless of the soil layer,the two soil types account for the largest proportions of calcium,magnesium,and manganese forms in exchanged calcium,acid-soluble magnesium,and reducible manganese.There is a positive correlation between available calcium and available magnesium in lime soil,and total nitrogen is one of the main external factors affecting calcium form content.Phosphorus content is the main factor affecting magnesium form content in lime soil and yellow soil,MnO and water-soluble form Manganese is related to organically bound calcium and effective magnesium,and the acceptance index has a greater influence.On the yellow soil,total potassium is the main influencing factor of calcium forms,and there is a correlation between various manganese forms and most calcium and magnesium forms.