Acidification and phosphorus enrichment affect silicon mobility in farmland soils
Silicon(Si)was an essential nutrient element for the growth and development of cereal crops such as rice.Soil pH affected the transformation and availability of Si,and there was a significant competitive adsorption effect between soil phosphorus(P)and Si.To investigate the effects of soil acidification and P enrichment on the availability and mobility of soil Si,P and Si competitive adsorption experiment,soil incubation experiment and Si fraction experiment were conducted.The results showed that the presence of P reduced the amount of Si adsorbed by the soil by 78%-350%when equimolar concentrations of Si and P were added simultaneously in the pH range of 3.5 to 6.4.Si sorption was less than that of P,soil acidification and P addition reduced Si sorption,and the effect of P addition in reducing soil Si sorption was more significant at higher pH(in the pH range of 3.5 to 6.4).Soil acidification decreased the content of movable Si,adsorbed Si,organic Si and Fe/Al/Mn-oxide Si,but increased the content of amorphous Si.The contents of movable Si and adsorbed Si were reduced by 22.47%-54.32%,10.72%-33.40%,respectively.P addition increased the content of movable Si by 4.07%-9.40%and adsorbed Si decreased by 1.19%-3.53%.The dissolution and sorption-desorption processes of soil Si were regulated by pH,and thereby affected the mobility of soil Si.P enrichment promoted the desorption of soil adsorbed Si,which in turn enhanced the mobility of soil Si.
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