Author
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Sharpe, Ronald |
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Harper, Lowry |
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Submitted to: Atmospheric Environment
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 5/19/1997 Publication Date: N/A Citation: N/A Interpretive Summary: In the U. S., hogs produce over 100 million tons of feces and urine each year and environmentally safe methods of disposal are difficult. Problems are exacerbated by concentration of animals into small areas. Iowa produces 25% of all hogs in the U.S. but has only 1.5% of the land. Nation wide about 30% of this waste is stored in anaerobic lagoons before effluent application to the land. Potential surface and/or ground water pollution from land application has been recognized for many years, but atmospheric pollution has only recently been identified. This study determined the emission rates of ammonia (NH3) and nitrous oxide (N2O) after application of effluent under field conditions. About 76% of the nitrogen (N) applied to the field was lost to the atmosphere within 48 hours after application. Such large losses make it difficult to recommend effluent application rates based on N concentrations and attempts to supply adequate plant N through the effluent could result in nutrient imbalances or accumulation of nutrients in the soil. In addition, absorption of atmospheric NH3 by natural ecosystems could contribute to eutrophication of lakes and streams, forest dieback, and plant species changes. Emissions of N2O after effluent applications were much smaller (6.6 lb/acre). Nitrous oxide is a radiatively active trace gas which contributes to global warming and small quantities of N2O can impact global warming potential since N2O has a long life-span (132 years) in the atmosphere. Technical Abstract: In the United States, swine operations produce over 14 million Mg of manure each year. About 30% of this manure is stored in anaerobic lagoons before effluent applications to land. Land application is often the preferred means of disposal and can supply nutrients for crop production. Land applications, however, can lead to gaseous emissions of ammonia (NH3) and nitrous oxide (N2O), both of which can be detrimental to the environment. The objectives of this research were to quantify gaseous emissions of NH3 and N2O from effluent applications under field conditions and to relate N2O fluxes to soil moisture content. Three applications of swine effluent were applied to oats (Avena sativa) during heading stage. Gaseous fluxes were determined from gas concentration profiles and the momentum balance transport coefficient. About 13% of the ammonium (NH4-N) was lost through drift or volatilization of NH3 during irrigation. An additional 69% was volatilized within 24 hours of application. Nitrous oxide emissions were low before effluent applications (30 mg ha-1d-1) and increased to 0.4 to 0.6 kg ha-1d-1 after irrigation. Total N2O emissions were 7.4 kg ha-1 which was about 13% of total N applied. The large losses of NH3 illustrate the difficulty of basing effluent irrigation schedules on N concentrations and the data indicates that NH3 emissions may be a more significant source of air pollution than N2O emissions. |
