Estimation of ammonia losses after application of liquid cattle manure on grassland

Field experiments under various conditions were carried out in Hohenheim and the Allgau to measure the effects of Liquid manure properties and meteorological factors on ammonia losses. The micro-meteorological method (IHF) and the wind tunnel method were used. Depending on the prevailing conditions the ammonia losses varied between 14 and 99% of the applied ammonium nitrogen. The relationship between the ammonia loss and the logarithm of the dry matter content of liquid manure was highly significant. The dry matter content also influenced the time course of the ammonia Loss. Solar radiation was the other major factor affecting ammonia loss. Compared to dry matter content and solar radiation;effects of other factors such as ammonium content and pH of liquid manure, air temperature, relative humidity and wind speed were small in the given range tested. Based on the relationships between the various parameters a simple model for estimation of ammonia loss was developed.