Emissions of ammonia and methane from a livestock building natural cross ventilation

Agriculture, especially animal husbandry, is a major source of the greenhouse gas methane as well as the gas ammonia. In order to develop reduction measures for emissions and immissions, two factors prove to be: firstly, to determine the emission mass flow from livestock buildings, and secondly, to understand the dispersion processes in its surroundings. The quantification of emissions from livestock buildings with naturally ventilation is a particularly difficult task. The experimental uncertainties are largely unknown but are expected to be considerable. Using poor quality emission data as model input in dispersion studies (wind tunnel or numerical simulations) will produce results with limited significance. Accordingly a field study has been conducted to quantify the emission mass flow from naturally ventilated livestock buildings. During two field campaigns in summer tracer gas experiments and measurements of gas concentrations within and around two naturally ventilated cow sheds in Mecklenburg-Vorpommern were carried out, in order to estimate the emission mass flow. It was found that the measured concentrations within the livestock building strongly depend on outside conditions such as e. g. the wind direction. Large uncertainties also arise from estimates of the air ventilation rate, which determines the emission mass flow. The data analysis shows high estimated ventilation rates of 1280-1380 m(3)/h/LU (1 LU = 500kg body weight) for cow shed 1 and 1140-1180 m(3)/h/LU for cow shed 2. These results suggest ammonia emission mass flow rates of about 4 g/h/LU for cow shed 1 and about 2 g/h/LU for cow shed 2, respectively.