Soil Strength and Porosities Associated with Cropping Sequences

The effects of cropping sequences on the strength and porosity of the Portneuf silt loam soil were studied in south‐central Idaho under normal field conditions. Undisturbed soil cores were collected from the surface 20 cm of seven fields with cropping histories ranging from continuous pasture to continuous beans ( Phaseolus vulgaris L.). The soil in all fields was a uniform silt loam developed under arid conditions. The pore size distribution and soil hardness were measured on the undisturbed cores as well as on bulk samples collected from each site. The results indicated that both the pore size distribution and the hardness are rather independent of cropping history. While both these parameters can be changed by mechanical manipulation, the soil soon reverts back to a stable range of values under field conditions.