Evaluation of soil potassium by Q/I measurement in some cultivated soils

The status of soil potassium in some cultivated soils were evaluated by Q/I measurement.Soils used could be divided into four groups according to the clay mineralogy.The soils in first(soil 7)and second group(soil 1,2,6)with predorminant vermiculite and illite and higher CEC showed higher potassium buffering capacity(PBC~K) and quantities of labile potassium(ΔK°),but lower potassium availability(AR_e~K).Con- versely,those in forth group(soil 3,8,9,10),consisting of kaolinitic soils with lower CEC, showed lower PBC~K and ΔK°,but highcr AR_e~K,and the others(soil 4,5)with most abun- dant illite and subdorminant kaolinite showed mediate potassium status