Abstract
We analyzed some greenhouse soils and soils from neighboring paddy fields for their base status using conventional methods and found that : (1) the base saturation percentages of some soils were far above 100%, and (2) that of some other soils were below 50%. Additional analyses of the soils for soluble salt, carbonate and exchangeable acidity suggested that : (1) the base saturation percentages above 100% were artifacts caused by the dissolution of nitrate, sulfate, chloride and carbonate salts of the bases in ammonium acetate, and (2) those below 50% were also spurious values due to overestimation of cation exchange capacity. Based on these experimental results, we concluded that the conventional method for the cation exchange capacity and exchangeable cation using 1 mol L^<-1> NH_4OAc solution buffered at pH 7 is not suitable for testing greenhouse soils. The NH_4OAc-extractable bases should be corrected for soluble salts and carbonate to determine the net exchangeable bases.
