NH3, N2O and CH4 emissions from milking cows housed in a tying stall (housing, manure storage, manure spraeding)

The project was aimed to quantify emissions of NH3, N2O and CH4 from milking cows housed in tying stalls under Austrian conditions. The investigations included each state of manure management: housing, storage and spreading. The measurements were repeated several times in course of the year to get an overview on the mean emissions. Gas concentrations were analyzed by a high resolution FTIR spectrometer. For the establishment of emission rates from diffuse sources a large open dynamic chamber was developed that is operated as an open-dynamic-chamber. It enables the quantification of emission rates in the field, under real conditions. In the tying stall no differences were found between a slurry based and a straw based system. About 80 % of the methane emissions were caused by ruminal fermentation. Ammonia emissions (240 mg NH3/(LU * h)) were below average values given in the literature, mainly due to the small emitting surfaces in a tying stall. N2O emissions amounted to 25 mg N20/(LU * h). During the storage period emissions from anaerobic storage and aerobic composting of FYM were compared. Two manure heaps, 8 t each, were stacked and the large open dynamic chamber alternated between the heaps three times a week to measure the emissions. After storage the FYM was spreaded and the emissions during and after spreading were also measured. The compost emitted more NH3 (671 (summer) and 303 (winter) g NH3/t FM) than the anaerobically stored FYM (248 and 244 g NH3/t FM). A major part of the total NH3 emissions from the anaerobically stored FYM emitted not during storage, but after spreading. The anaerobically stored FYM emitted more greenhouse gases (CH4 and N2O) (61.5 (summer) and 39.1 (winter) kg CO2-equiv./t FM) than the composted FYM (13.8 and 36.5 kg CO2-equiv./t FM.). The greenhouse gas emissions from the winter compost were due to heavy snowfalls that wetted the FYM and suppressed a sufficient oxygen supply. Composting of FYM can substantially reduce greenhouse gas emissions from manure management. The NH3 emissions could be further reduced by adding additional straw. (author)