Experimental simulation of the results of clay translocation in the B horizons of soils; the formation of intrapedal cutans

A series of laboratory experiments designed to simulate the formation of intrapedal cutans was carried out through repetitive leachings of undisturbed blocks of soils (6 × 3 × 4 cm³) by suspensions (0.3% concentration) of clay-sized particles from two commonly occurring Bt horizons in southern England. After leaching, thin sections were cut and point-counted, thus enabling the visual recognition, replication and potential quantification of newly formed intrapedal pore and grain cutans. They all exhibit morphological, physical and optical properties diagnostic of illuviation cutans, and can be differentiated from inherited cutans on these and on spatial grounds. A general relationship between numbers of newly formed cutans and increasing leaching cycles was observed, and experimental support obtained from these soils for the significance of the complex, three-dimensional spatial pattern of tubular pores in the translocation of clay-sized materials and the formation of these argillic, Bt horizons. This study highlights both the value and difficulties of designing laboratory-based, soil/water/gravity studies in pedology.