USE OF A FIELD MORPHOLOGY RATING SYSTEM TO EVALUATE SOIL FORMATION AND DISCONTINUITIES

Abstract

We used a field soil morphology rating system to evaluate a chronosequence of soils in the northeastern San Joaquin Valley, California. Relative horizon distinctness (RHD) ratings generally were less than 10. RHD ratings greater than 10 were obtained for observed and suspected parent material or soil formation discontinuities. Although monogenetic soil formation will result in high RHD ratings in some cases, the soils tested here usually had high RHD ratings at discontinuities. Relative profile development (RPD) ratings increased with age. Maximum values were in the A horizons of younger soils and in the B horizons of older soils.