THE RESIDUAL EFFECT OF SOIL LOSS ON THE CHEMICAL AND PHYSICAL QUALITY OF 3 SOILS

Soil particle size distribution, bulk density, water desorption, water-stable aggregates greater than 0.25 mm, Cs-137 content, organic carbon (OC), total nitrogen (N(t)), sodium-bicarbonate-soluble phosphorus (P(a)), exchangeable cations, and cation exchange capacity, were measured in three contrasting soils that had lost soil by erosion and tillage to different degrees. Included were sites that had been used in an erosion study between 1946 and 1959 at the Central Experimental Farm, Ottawa. The amount of soil loss was calculated from Cs-137 loss and depths to contrasting layers, and deposition was estimated from the depths of Ap horizons. Soil loss was closely related to slope position and land use. Contents of OC, N(t), and P(a) were reduced by soil loss. They were not restored at the medium- and coarse-textured sites after 17 years of continuous grass cover, but OC and N(t), and aggregate stability, were restored at the fine-textured site after 27 years of grass cover.