Transformation Character of Percarbamide in Acidity and Alkalinity Soil

Percarbamide is an important chemical product and a new fertilizer, and has been used in china in recently years. Changes of pH, volatilization of ammonia, percarbamide -N transformation and active Al in 3 acidic soils and 3 alkali soils caused by percarbamide application were studied. The results indicated that:effects of acidity and alkalinity of soil on percarbamide hydrolysis were correlated with the concentration of percarbamide. At 25 ℃, the changes of pH in acidic soils increased quickly , while the changes of pH in alkali soils increased first, then fell, rose again, with the increasing concentrations of applied percarbamide. The time-course experiment revealed that the increase of soil pH was short-term, with a subsequently slow drop after reached their maximum, and pH of 3 alkali soils were less than original after 2 weeks. Ammonia volatilization intensity, NH-N and NO-N were greatly similar to soil pH, they followed the changes of soil pH:rose to maximum, and then fell between 3 acidic soils and 3 alkali soils. The maximum of ammonia volatilization intensity in 3 acidic soils and 3 alkali soils had persisted for 7th day and third day respectively; NH-N and NO-N in 6 soils rose to maximum after 2~4 weeks, then dropped and kept constant value. Soil exchangeable Al decreased sharply with the increasing concentrations of percarbamide in 3 acidic soils, and there was a significant negative relationship between soil exchangeable Al and soil pH in a short-term period.