INFLUENCE OF ANION MOBILITY ON IONIC RETENTION IN WASTE WATER IRRIGATED SOILS

The concept of anion mobility as a determinant of soil leaching rate was illustrated in a waste water irrigation study. Anion adsorption appeared to affect the leaching of H//2PO//4** minus and SO//4**2** minus , but not Cl** minus , which percolated freely through the soil. The mobility of NO//3** minus was primarily regulated to nitrification and plant uptake. The most pronounced change in solution chemistry was an alkalinity decrease of approximately 80% as wastewater entered the soil due to lowering of pH (7. 5 to ca. 6. 5), and to gaseous CO//2 loss from solution. This alkalinity decrease accounted for most of the total ionic retention in the soil which ranged from 40-60% of waste water input.; The concept of anion mobility as a determinant of soil leaching rate was illustrated in a waste water irrigation study. Anion adsorption appeared to affect the leaching of H2PO4- and SO42-, but not Cl-, which percolated freely through the soil. The mobility of NO3- was primarily regulated by nitrification and plant uptake. The most pronounced change in solution chemistry was an alkalinity decrease of approximately 80% as waste water entered the soil due to lowering of pH (7.5 to ca. 6.5), and to gaseous CO2 loss from solution. This alkalinity decrease accounted for most of the total ionic retention in the soil which ranged from 40-60% of waste water input.