Effect of pasture or wheat cropping on the permeability of a weakly weathered soil to sodic solutions

Abstract

Laboratory estimates of permeability of soil from a rotation trial to solutions of varying sodium adsorption ratio (NaAR) and electrolyte concentration (EC) were made. Soil samples from under 2 years of wheat or 2 years of pasture, as well as a subsoil sample were used. At high EC (5 meq./litre), an increase in NaAR from 0 to 44 resulted in a 25% decrease in relative permeability but there was no significant difference between the soils at each NaAR. At low EC (≃ 0 meq./litre), an increase in NaAR resulted in an average relative permeability decrease of 70%. Significant differences occurred in permeability between wheat and pasture soils at NaAR of7.4 and 16.7. These results were related to the role of organic matter on structural stability at moderate Na^002B; levels.

Keywords:

• organic matter
• salt concentration
• exchangeable sodium percentage
• sodium adsorption ratio
• crop rotation
• soil chemistry