Research On Adsorption And Desorption Of Magnesium In Soil

Magnesium is necessary middle Nutrition Element for plant grown, which is not only play important part performance for photosynthesis as component of chlorophyll, but also Activating Agent of many enzyme in plant. The chlorophyll couldn't compose and the photosynthesis was be restrict when plant lack for Magnesium that will be effect metabolism of plant down to the plant couldn't growth normally and it's output and mass down. Magnesium's chemistry Behavior in soil is complicated and it's adsorption and desorption in soil will effect it's validity that will control Magnesium's supply. Magnesium's chemistry Behavior in soil had important effect for it's validity so we need to research Magnesium's fertilizer in soil in Chongqing and status of it adsorption and desorption to service for research on Magnesium's biologic validity in soil.To research adsorption and desorption yellow soil, purple soil and lime soil which was representative soil in Chongqing and choice befitting equation simulate it and more make it's adsorption and desorption curve of and Analysis on correlation with pH and organic in soil and combine with change of charge in soil to discuss mechanism of infection. The main results were as follows:1. The Status of Magnesium's adsorption and desorption in Chongqing soil.The rules of Magnesium's adsorption in three type soil was consistent as it's increase with Balanced Salt Solution's consistence increase and its adsorption rate was down. Equation Langmuir can simulate its status well. Yellow soil had most intensity ability of Magnesium's adsorption and lime soil had lowest ability of it. The gradation of ability of Magnesium's adsorption was: Yellow soil>purple soil>lime soil; The maximum adsorption X_m of yellow soil was 2010.97mgkg' and purple soil was 1895.27mg·kg^-1 which were more than The X_m of lime soil as 981.91mg·kg^-1. The equilibrium const K of yellow soil was 0.0777 and purple soil was 0.0743 which higher than lime soil as 0.0409.The gradation of ability of Magnesium's desorption is: yellow soil>purple soil>lime soil. The direction that the amount and the rate of desorption was increase with adsorption amount's increase was obvious in yellow soil, but it's not obvious in lime soil which had least rate of desorption was 9.62% and maximum rate desorption was 17.59%. The yellow soil which had most intensity ability of adsorption was most intensity ability of desorption and the lime soil which had lowest intensity ability of adsorption was lowest intensity ability of desorption which was because of the character of soil.2. The infection to Magnesium's adsorption with organic in soilThe yellow soil's content of organic had most descend as declining 2.5% and the content of charge and ability of adsorption had most descend too as CECv descend 6.25cmol·kg^-1, X_m descend from 2010.97mg·kg^-1 to 1647.66mg·kg^-1, The purple soil's content of organic descend 1.9% and its CECv descend 2.26cmol·kg^-1 and Xm descend from 1895.27mg·kg^-1 to 1746.55mg·kg^-1; The lime soil's content of organic descend 0.3% and its CECv declining 2.29cmol·kg^-1 and X_m descend from 981.91mg·kg^-1 to 861.91mg·kg^-1, which of those diversification was minimal. The Magnesium's diversification adsorption was consistent with the diversification of charge content in soil that show the infection to Magnesium's adsorption with organic in soil was achieve by infection charge content in soil so that to infection its Electrostatic -Adsorption.3. The infection to Magnesium's adsorption with pH in soilThe infection to Magnesium's adsorption with pH in yellow soil was most obvious. Its diversification of Magnesium's adsorption was consistent with the diversification of charge content in soil, The ability of Magnesium's adsorption was buildup along with pH hoist which because of the diversification of pH buildup its Electrostatic-Adsorption. The CEC_8.2 enhance from 11.12cmol·kg^-1 to 25.33cmol·kg^-1 and CEC_V enhance from 7.47cmol·kg^-1 to 17.79cmol·kg^-1 and X_m enhance from 1336.25mg·kg^-1 to 2054.77mg·kg^-1 and enhance from 0.0506 to 0.0749 when pH enhance from 3.5 to 7.5. Although The direction that diversification of charge along with pH diversification was obvious in lime soil, the diversification of Magnesium's adsorption wasn't obvious which it's because of its Clay Minerals had low avidity with Magnesium and the diversification of Magnesium's adsorption was obvious when pH was 5.5～7.5. Although purple soil was constant charge soils, it had little variable charge and its diversification of charge along with pH diversification wasn't obvious and diversification of Magnesium's adsorption was puniness. Its ability of Magnesium's adsorption was buildup when pH at 5.5～7.5 because of the pH buildup made it had specific-adsorption, Its CEC_8.2 enhance from 23.32cmol·kg^-1 to 27.01cmol·kg^-1 and CEC_v enhance from 2.21cmol·kg^-1 to 5.11cmol·kg^-1 and X_m enhance from 1468.68mg·kg^-1 to 2025.38mg·kg^-1 and enhance from 0.0536 to 0.0686 when pH enhance from 5.5 to 7.5.