Soil Crusting and Some Factors Affecting It

Abstract

AbstractPhysical studies were made of natural soil crusts and of the soils beneath them. Artificial crusts (briquets) were prepared by several methods and their modulus of rupture and bulk density were determined. The natural crusts had a much greater bulk density, a higher percentage of particles < 0.10 mm. in diameter, and a lower degree of aggregation than the underlying soil. The modulus of rupture of artificial crusts was increased by longer periods of drying at 105°C.; by slow drying (using lower temperatures); by compacting the dry soil in the briquet molds; by the beating effect of raindrops; and by puddling the soil before putting it into the molds. It was decreased by successive wetting and drying, but partial drying and rewetting gave results which varied with different soils. High modulus of rupture values were obtained with soils containing large amounts of soilt or total material < 0.10 mm. and, 2:1 type clay. Bulk densities were essentially the same: (a) for dry soil used in preparing briquets and the same type of soil beneath natural crusts in the field; and (b) for artificially prepared briquets and natural soil crusts.