The Correlations and Prediction models of Cation Exchange Capacity in Three Soils in Henan

Cation-exchange capacity(CEC) is an important soil property in describing soil fertilization and nutrient availability for plant growth.Measurements of CEC,however,are often not available or have been measured using different analytical methods.The need,therefore,exists to develop alternative procedures to predict CEC from accessory soil properties.In this study,1177 soil samples,correlation and regression analysis were used to examine the relationships between CEC and soil organic matter(SOM),pH value,clay content,sand content and other soil properties.The results were as follows:(1) CEC: Shajiang black soil Paddy soil Cinnamon soil;topsoil(0-20 cm) subsoil(20-40 cm).CEC of all the three soils,Shajiang black soil,Cinnamon soil and Paddy soil(0-20 cm) decreased 15.7%,12.7%,6.5% than the second country general detailed soil survey;(2) For Shajiang black soil(n=259,0-20 cm) and Cinnamon soil(n=199 0-20 cm),CEC were significantly and negatively correlated with pH value and 0.02-2 mm sand content.However,clay content( 0.002 mm) was significantly and positively correlated with CEC for Cinnamon soil;For Paddy soil(n=322,0-20 cm),CEC was significantly and positively correlated with SOM and clay content( 0.002 mm),and negatively correlated with sand content(0.02-2 mm);(3) 1177 soil data were used to develop six models of the three typical soils using general linear models with scientific basis.In general,predictions of CEC correlated closely with SOM content,pH value,clay content and sand content.Furthermore,there existed other factors which interfering the accuracy of CEC predictions of these models