Effect Of Silicon On Phosphorus Adsorption Soils And Phosphorus Availability

Phosphorus is the necessary nutrient for plant growth.In the practice of agricultural production,how to use phosphorus efficiently has been paid much attention.At present,there are many researches on the realationship between silicon and phosphorus in soil at home and abroad,but it does not take into account the basicity of silicate and the effect of cation on the reaction system.Therefore,it is difficult to judge whether the effect of silicon itself.In this paper,selected potassium silicate as exogenous silicon,the effect of exogenous silicon on the adsorption of soil and iron oxides and phosphorus activity was studied on the basis of eliminating the influence of alkaline and potassium ions of potassium silicate.Combining with mineralogy and soil chemistry,the effects and mechanism of exogenous silicon on the adsorption characteristics and activities of soil phosphorus were discussed.The effects of exogenous silicon on the chemical behavior and activity of soil phosphorus were systematically studied.It provide a scientific basis for rational use of silicon and phosphorus fertilizers,improving the utilization rate of phosphate fertilizer and reducing agricultrural non-point source pollution.The main results and conclusions are as follows:1.Under the same phosphorus adsorption equilibrium concentration,the addition of silicon can reduce the adsorption capacity of phosphorus in soil.The results of three isotopes?Langmuir equation,Freundlich equation and Temkin equation?have a significant level of isothermal test data for soil adsorption.In the Langmuir equation,the values of adsorption equilibrium constant?K1?,maximum adsorption capacity?Xm?,and maximum buffer capacity?MBC?decreased with the increase of exogenous silicon application.So that the adsorption rate of phosphorus on the soil slowed down,the maximum adsorption capacity decreased,reducing the soil adsorption capacity of phosphorus.In the Freundlich equation,the adsorption capacity?K2?and the adsorption intensity?n?decreased with the increase of the amount of exogenous silicon,which indicates that the application of exogenous silicon will lead to the reduction of phosphorus adsorption sites and the adsorption of phosphorus on the force.2.Under the same phosphorus adsorption equilibrium concentration,the exogenous silicon can inhibit the adsorption of phosphorus from the ferrihydrate and goethite.Three equations?Langmuir equation,Freundlich equation and Temkin equation?can be well fitted when describing the adsorption characteristics of phosphorus on iron,but the results of Langmuir equation are the best.In the equation,as the amount of exogenous silicon increases,the Ki decreases,the MBC decreases and the Xm remains essentially unchanged.Further studies have shown that the application of silicon can make the iron oxide adsorption surface of the phosphate group redshift,tend to be more unstable state.3.After the application of exogenous silicon,the activity of H₂PO₄⁺ increased and the phosphorus potential increased,indicating that the phosphorus intensity of soil increased.The release of soil phosphorus increased,indicating that exogenous silicon could promote the activation of phosphorus in soil.At the same time,the soil phosphorus saturation increased,increased by about 1.4 times,indicating that the application of silicon can increase the soil phosphorus mobility and activity.In summary,the application of silicon can increase the activity of phosphorus in soil.The results of pot experiment showed that the application of phosphorus and silicon promoted the growth of rice plants,which could increase plant height and biomass.The application of silicon and phosphorus increased the phosphorus content of rice plants in two soils.