| Popis: |
INFILTRATION rate tests were run on a sand and on a loam soil after the natural soil air was evacuated and replaced with C02 gas. When the C02 was free to escape at atmospheric pressure, the infiltration rates were 50% higher in the sand and 56% higher in the loam 500 sec. after the start of infiltration than observed during identical tests, with natural soil air. When the C02 gas was trapped ahead of the wetting front, the higher hydraulic conductivities which caused the increased infiltration rates when the C02 was not trapped were nullified in the sand since the gas entrapment reduced the infiltration rate to values as low as or lower than when the air was trapped. When the C02 gas was trapped in the loam soil during infiltration, the infiltration rate remained as high as when the C02 gas was not trapped because the exchange of hydrogen ions for calcium ions in the silty clay loam soil caused a reduction in gas pressure which, in turn, increased the hydraulic conductivity and therefore the infiltration rates. |
