Technical Abstract: Ammonia (NH3)volatilization is a major nitrogen (N) loss process for surface-applied manures. There is growing public concern that current manure management practices may be promoting NH3 enrichment of streams, estuaries, and coastal waters. Agriculture is the major source of NH3 emissions to the atmosphere, contributing an estimated 90% of total emissions. Land application of manures is estimated to be the largest source of agricultural NH3 in the Northeast. Ammonia losses from land application can vary from 5-95% of the manure ammonium-N (NH4-N) depending on management practices and environmental conditions. The major factors affecting manure NH3 loss from land applications are i) manure characteristics (dry matter content, pH, NH4-N content), ii) application technique (incorporation, band application, time of application), iii) soil conditions (soil moisture, soil cation exchange capacity, plant/residue cover), and iv) environmental factors (temperature, wind speed, rainfall). The largest losses occur from surface applications to soils with high residue cover under high evaporation weather conditions. The most effective method to minimize loss is immediate incorporation by direct injection or by tillage. The particular management choice will depend on the circumstances of the individual livestock producer. Adopting manure management practices that conserve ammonium-N can lower fertilizer costs and reduce odors and the likelihood of nutrient loss in runoff, thus providing both economic savings to the farmer and environmental benefits to society.