Gaseous movement in soil varies with soil's physicochemical properties and biochemical oxygen demand. Diffusivity patterns of four different types of soil (sand, silt, sandy silt, and clay) were examined and sand have shown the highest rate of diffusivity increase with the decreasing soil moisture content. Raw cow manure was then added to the sandy soil at four different rates 0, 20,40, and 80 Mg/ha. Depletion of soil oxygen and changes of carbon dioxide and ammonia for different concentrations were compared against the control. The oxygen depletion or carbon dioxide and ammonia accumulation reached the highest level at initial 16 hour followed by gradual reversal to a steady state. A significant amount of oxygen depletion was noticed with the different concentration levels. Oxygen depletion had shown an oscillatory behavior towards zero. Among different concentrations that of 40 Mg/ha showed the highest oscillatory behavior, but the shortest time was required to recover its original oxygen level. Thus the 40 Mg/ha application of organic matter is seems to be the optimum level for sandy soil.

Barrington, Suzelle (Supervisor)