Browsing by Subject "Enzyminhibitor"

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Grundlagenuntersuchungen zur Wirkung neuartiger Ureaseinhibitoren in der Nutztierhaltung
(2008) Reinhardt-Hanisch, Annett; Hartung, Eberhard
Due to the agreements held by Germany in international and national programmes to reduce climate and environmental deterioration particularly in relation to ammonia emissions from livestock housing, additional measures have to be taken in order to ensure that international and national objectives will be achieved. Within the framework of a BMBF-funded interdisciplinary research project, new types of urease inhibitors had been tested for application in animal housing. The present work shows the necessary basic studies, which formed the basis for the investigations under conditions similar stall conditions and in practice stall in the second part of the project (LEINKER, 2007). The main objective of the present work was to investigate the effect of different urease inhibitors on urea hydrolysis, and thus to quantify the ammonia release of urea applied on cattle slurry under standardized, reproducible and controlled laboratory conditions and to investigate possible influencing factors (Pre-screening). Subsequent objectives result in the following: development of an appropriate measuring system and implementation of a standardized test, study of various urease inhibitors at different substrate temperatures and inhibitor concentrations, selection of the urease inhibitor which has the best reduction effect, and quantification of other factors influencing the effect of the selected urease inhibitor. In order to assess the inhibitor effect, the protonated ammonium and the available ammonia in slurry should be detected by means of conducting slurry analysis. In addition, the first indications of a long-term effect of the selected urease inhibitor, its impact on biogas accumulation, and its effect on liquid swine manure should be derived. In order to carry out the investigations, a water-tank measuring system had been configured and validated. The 28 measuring tanks of the measurement system, where each tank was filled by 2 l of slurry, worked according to the principle of dynamic chamber and were kept at constant temperature using a water bath. A gas analysis based on NDIR spectroscopy had been used in order to sustain continuous measurement of ammonia concentrations in the measuring device. The standardized test, applied in the main experiments, had been developed in the preliminary experiments. Among the five pre screened urease inhibitors (four new active agents + reference NBTPT active ingredient), the urease inhibitor D is selected for further investigations in the project, as this is the best inhibitor having significant reduction effect, which was in general dependent on the substrate temperature and the inhibitor concentration in terms of ammonia release. For an effective reduction of ammonia release, it seems useful to deploy more often smaller quantities of the inhibitor. The urease inhibitor D showed a significant reduction effect regardless of the origin and the layer thickness of the respective liquid manure. In comparison with the urease inhibitor D treated variants, more urea is significantly converted to ammonia and ammonium-nitrogen at a layer thickness of 4 mm than at a layer thickness of 90 mm. Apart from the ammonia release, the resulting nitrogen balance of all the tests showed no indication of further significant gaseous nitrogen losses, e.g. as nitrous oxide. In the experiments, no significant influence of urease inhibitor D had been detected on the (urea independent) basic release of ammonia from the respective liquid manure resulting from the degradation of organic substances. In practice, this means that the use of urease inhibitors is only reasonable in the presence of urea. The preliminary related investigations showed that the duration effect of the urease inhibitor D is dependent on temperature; no adverse effects caused by the inhibitor D of treated slurry on the biogas accumulation. Similar relations, as in cattle slurry, had been recognized and showed for the urease inhibitor D in pig slurry. As part of the investigations, a urease inhibitor is selected for cattle and pig slurry urea hydrolysis, and thus the ammonia release is significantly reduced. The basic investigations afforded an important contribution to the expansion of knowledge in this area, and lead on the other hand to develop new techniques in order to reduce the ammonia emissions from livestock housing.