Effects of Applying Percarbamide on Soil pH and Exchangeable Content of Five Metals in Different Acidic and Alkaline Soils,China

The effects of percarbamide on the changes of pH and soil exchangeable Mn,Cu,Zn,Ca and Mg contents in 3 acidic soils and 3 alkaline soils in China were studied by indoor incubation test.The results showed that the pH of acidic soils increased quickly,and pH in alkaline soils increased first,then fell,rose again,with the increasing concentrations of applied percarbamide,and the changing range of pH in alkaline soils was smaller than that in acidic soils.The time-course experiment revealed that the rise of soil pH was short-term,with a subsequently slow drop after reaching their maximum,and pH value of 3 alkaline soils was less than the original pH value after 9 days.The dynamic changes of exchangeable mentals(Mn,Cu,Zn) in acidic soils were negative correlated with soil pH,and the contents of Mn,Cu,Zn decreased first and then increased gradually.However,the changes of Mn,Cu,Zn in alkaline soils were not very obviously.There was a positive relationship between soil Ca,Mg and soil pH,that was,the higher pH value was,the richer exchangeable Ca,Mg contents were.New negative effects caused by applying percarbamide as a new fertilizer on availability of metals in different acidic and alkaline soils was not found.