Ammonia Volatilization from Sewage Sludge Applied in the Field1
- E. G. Beauchamp,
- G. E. Kidd and
- G. Thurtell2
Volatilization of ammoniacal nitrogen from newly applied anaerobically digested sewage sludge was measured in the field using an aerodynamic method in May and Oct. for 5- and 7-day periods, respectively. Sludge was applied in a circular area of 0.405 ha at rates of 116,480 kg/ha (150 kg NH4+-N/ha) and 134,400 kg/ha (89 kg NH4+-N/ha) in the May and Oct. experiments, respectively. Windspeed and atmospheric ammoniacal N was measured at 10, 50, 100, and 150 cm above the soil surface providing time averaged vertical profiles at the center of the area from which ammoniacal N flux was estimated. Flux was determined on the premise that NH3 molecules leaving a horizontal surface must be carried through a vertical plane by horizontal air flow.
Fluxes generally followed a diurnal pattern with maximums occurring at about midday. Flux generally decreased with time in an exponential manner. Thus, the “half life” of ammoniacal N applied in the sludge was 3.6 and 5.0 days for the May and Oct. experimental periods, respectively. Of several meteorological variables measured, air temperature appeared to be most closely related to flux rate especially in the two or three days following application. It was estimated that, during the 5-day experimental period in May, 60% of the 150 kg ammoniacal N/ha applied in sludge was volatilized. During the 7-day experimental period in Oct. 56% of the 89 kg ammoniacal N/ha applied was volatilized.
Sampling the sludge layer and soil beneath it during and after the Oct. experimental period resulted in considerable variability in ammoniacal N estimates and, hence, in volatilization estimates.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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