Genesis of Solonetzic soils as a function of topography and seasonal dynamics

Abstract

A Gleyed Black Solonetz at a depressional slope position, a Black Solonetz at a lower slope position, a Black Solodized Solonetz at a mid-slope position, and a Black Solod at an upper slope position in central Alberta, were investigated using chemical, physical and mineralogical techniques to determine the role of topographic position and season in their genesis. Solonization, as indicated by electrical conductivity (EC) values < 4 dS m−1 and exchangeable sodium percent (ESP) values > 15% in the B horizon, was greatest in the Gleyed Black Solonetz, and then decreased in the soils upslope. Solonization occurred during the spring, summer and fall in the B horizon of the Gleyed Black Solonetz and Bnt1 horizon of the Black Solod, and during the spring in the B horizon of the Black Solonetz, Bnt1 horizon of the Black Solodized Solonetz, and Bnt2 horizon of the Black Solod. Solodization, as indicated by the development of Ae and AB horizons, acidic conditions and higher dithionite-extractable Al in the upper sola, and high exchangeable acidity in the upper B horizons, was greatest in the Black Solod at the upper slope position, moderate in the Black Solodized Solonetz at the mid-slope position, and absent in the two soils at the lower slope positions. Solodization as reflected by exchangeable acidity, also exhibited seasonal fluctuations, particularly in the upper B horizons. Seasonal variations of exchangeable Na, Ca and Mg in the B horizons, however, were slight to nonexistent. Topographic position and seasonal fluctuations of soluble salts and exchangeable acidity in the B horizons played a major role in the genesis of soils in this Solonetzic catena. Key words: Solonetzic catena, solonization, solodization, topography, seasonal dynamics