Forms of acidity and base buffering in mineral horizons of podzolic and bog-podzolic soils in the northeast of european russia

摘要

Forms of acidity and base buffering in KCl extracts and water suspensions from mineral horizons of podzolic and bog-podzolic soils have been studied.It is found that soil acidity increases at initial stages of hydromorphism.The main buffering reaction upon the titration of water suspensions is the deprotonation of functional groups of organic acids and OH~- groups on the surface of the particles of Fe and Al hydroxides.The base buffering of water suspensions upon their titration to pH 8.0 correlates with the exchangeable acidity but exceeds it at the expense of participation of less acidic components;it is almost equal to the total soil acidity,as both phenomena have a common nature.All the soils studied are characterized by a common regularity in the buffer properties of water suspensions:their base buffering in particular pH intervals increases with an increase in the pH conditions,the values of exchangeable acidity are overestimated in comparison with those obtained with the use of potentiometric control of pH values.