Browsing by Person "Gronow-Schubert, Stephanie"

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Untersuchungen zum Emissionsgeschehen von Ammoniak und Methan in der Mastschweinehaltung
(2017) Gronow-Schubert, Stephanie; Gallmann, Eva
The growing of feed crops, the production of farm livestock and the processing of livestock products, along with the associated use of farmland for this entire production chain, all engender greenhouse gases on a worldwide scale. In this respect, ammonia and methane emissions are directly associated with livestock farming including the feeding of pigs for slaughter. The main aim of the work presented in this thesis was investigation of emissions produced in this way, and into selected strategies applied for reducing ammonia and methane release, particularly in management of liquid manure inside a fattening unit. In this context, the paper focusses on the three approaches – measuring, analysing and modelling - which are accordingly established as the following part-targets: • Applying emission reduction strategies as part of liquid manure management in a conventional fattening unit and comparing the resultant emissions with those from a reference system where no emission reduction actions had been taken. The selected emission reduction strategies should be practicable and sustainably applicable in existing livestock housing systems. • Analysing the main factors of influence on emissions throughout the fattening period during different seasons of the year, with special consideration of time series effects and regressions. • Examining the possibilities of substance flow modelling, application to own measurement data rather or for assessing the potential of emission reduction methods as well as evaluation of the selected approach for substance flow modelling. In-barn liquid manure management with fattening pigs markedly influences ammonia and methane emissions whereby the concrete reduction potentials are not yet sufficiently clarified. Within this study, a first work package compares, through a case control approach, the liquid manure management strategies - weekly emptying of the liquid manure channel as well as covering of the underfloor stored liquid manure surface as well as the addition of Effective Microorganisms to the liquid manure – with the strategies tested for emission reduction potential and compared over a feeding cycle in each case with the stored manure method as reference. The pig housing used in the trial was divided into two compartments (experimental and reference compartment) each holding 50 animals. In quasi-continuous measurement, incoming air, compartment and exhaust air ammonia and methane concentrations, temperatures of incoming air, compartment and exhaust air, and the temperature and pH of the liquid manure, were all recorded. Additionally, liquid manure samples were analysed in 14-day rhythm and the level of liquid manure measured as well as the degree of dirtiness of pen floors. Also recorded were pig weights and performance or feeding data. No further differences in terms of feeding, ventilation or management existed between trial and reference compartments. The applied reduction strategies were able to partially reduce ammonia and methane emissions (weekly emptying of liquid manure channel: methane emission rates reduced by 39 % based on emission rate in grams per day and livestock unit; liquid manure cover: 13.8 % ammonia emission rates reduction in grams per day and livestock unit), had in part no effect, or even a negative influence on the emissions (weekly emptying of the liquid manure channel: no effect on ammonia emissions; liquid manure cover: 119.9 % rise in methane emission rates in terms of grams per day and livestock unit). The selected interval of one week between emptying the liquid manure channel was not sufficient as a reduction strategy. With covering of the liquid manure surface underfloor, it is important to consider that the almost airtight sealing of the liquid manure surface delivered favourable conditions for methanogenesis. The influence of the addition of Effective Microorganisms to the liquid manure on the emissions of ammonia and methane was marginal. The emissions of ammonia increased of 8.3 % and the emissions of methane of 5.9 %. The evaluations (time series and regression analyses) of the data from the reference compartments from a total of four feeding cycles (two summer and two winter cycles) comprised the second work package. The time series analysis enabled insight into the relationships between the ammonia and methane emissions in terms of time, and insights into the influential factors affecting release and transport of the gases. For example, the time-related influences of high temperatures on the system “fattening unit” and on the release of emissions, could be graphically shown. The time series analysis gave indications as to how dynamic, or how stable, climatic conditions can be in pig housing. The regression analyses clearly showed that the emission process, with ammonia as well as with methane, is influenced particularly through the amount of liquid manure involved, the temperature and the air volume flow. In the same way, the distance between the liquid manure surface and the slatted flooring (‘headspace’) was found to have direct influence on the release of ammonia and methane from the liquid manure. A larger ‘headspace‘ correlated with reduced emissions and vice versa. Following recording and statistical evaluation of the emission data, the contribution that can be made through substance flow modelling of ammonia emissions towards increasing knowledge on the emission process and on methods for its reduction within pig housing was examined as a third work package. This involved the transfer of selected recorded data into the substance flow model. Serving as basis was the model from CORTUS et al. (2010a) adapted in three steps to take account of the conditions in the pig housing being used. The constructional outline of the trial livestock housing served as system limit. Berkeley Madonna 8.3.18 software was used for numerical integration of the differential equation system. Own data was applied for calibration and validation, in each case taken from the reference compartment of two different feeding cycles. In principle, the adapted model was capable of modelling ammonia concentrations and emissions. In addition, the influence of the liquid manure temperature and pH value of the liquid manure could be depicted. However, the model generally reacted sensitively to temperature and pH values. Because of this, the model underestimated and overestimated recorded values, in part substantially. An important influence on the model accuracy appeared to be related to the submodel considering urine puddles. For the purposes of own modelling, this submodel was cut out of the main model during its adaptation according to the recorded data. Compared to recordings, modelling of gas concentrations and emissions offers the advantage of cost-efficient and time-saving estimations of emission potential for different housing systems, e.g. for feeding pig production. Calibration and validation, as well as adaptation to suit the type of application requires, however, particular care and expertise. Through the various methods for measurement, analysis and modelling that were applied, the work reported here contributes to better understanding of the emission process and the reduction of emissions, particularly in the case of liquid manure management in feeding pig production.