Browsing by Subject "Klimarelevante Gase"

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Emission von Ammoniak (NH₃) und Lachgas (N₂O) von landwirtschaftlich genutzten Böden in Abhängigkeit von produktionstechnischen Maßnahmen
(2003) Leick, Barbara Cornelia Elisabeth; Engels, Christof
The goal of this research was to quantify event-based NH₃ and N₂O emissions in various farming systems and to propose emission-avoidance strategies. Emission measurements were made on pasture land (Allgaeu, Hohenheim) and on cultivated fields (Hohenheim, Biberach). These measurements were made after applying organic and mineral fertilizers, after incorporating crop residues, and after freeze / thaw cycles; furthermore, experiments were conducted using container plants of different species (leguminous, and non-leguminous) and different fertilizers. NH3 emissions data was gathered under field conditions using the wind tunnel method and the IHF method (Integrated Horizontal Flux). In the container experiments, data was gathered by taking photo-acoustic measurements. N₂O emissions data was compiled using closed chambers (Hohenheim measuring chambers) and using an open-chamber system in which an exchange occurred between the air in the chambers and the ambient air. N₂O levels were determined using a gas chromatograph or by photo-acoustic measurements. The NH₃ emissions after applying liquid manure to pasture land varied between 11 and 40% of the total nitrogen applied. Emission levels of less than 20% occurred when it rained shortly after spreading liquid manure causing it to be washed into the soil. The application technique (splash plate, surface banding and liquid manure injection) had no apparent influence on NH₃ emissions under these conditions. The N₂O emissions after liquid manure fertilization on pasture land in Hohenheim were 0.16% of the total NH4+-N. In comparison, the emissions in the Allgäu were between 1.7 and 2.3% of the total NH4+-N applied. Liquid manure injection led to higher emissions as did application using a splash plate. In the Allgäu, the N₂O emissions after mineral-nitrogen fertilization were markedly lower (0.3 to 0.8% of applied N) than after liquid manure application. In Hohenheim, the nitrogen form had no distinct influence on the emissions (<0.16% of applied N). Definitive differences between the two locations were observed during the experiments. These differences were based on N₂O losses due to the respective soil and weather conditions (precipitation, temperature). The higher emissions after applying liquid manure compared to those after applying mineral nitrogen fertilizer are explainable in that aside from the nitrogen compounds found in liquid manure, carbon compounds which promote the microbial formation of N₂O were also entering the soil. The NH3 emissions after liquid manure fertilization on cultivated fields using a splash plate varied between 25 and 35% of the applied NH4+-N. By using a slurry cultivator which combines application with immediate incorporation, the NH3 emissions can be clearly reduced to 6% of the applied NH4+-N. Application with a drag hose, in comparison to using a splash plate, did not always result in an emission reduction; however, in taller plants, a readable emission reduction was measured. The N₂O emissions after liquid manure application on cultivated fields varied between 0.1 and 2.2% of the applied NH4+-N whereby the emissions after guided application with the drag hose were always higher than after using a splash plate. Mineral fertilizer had lower N2O emissions (<0.13% of applied N), especially when ammonium fertilizer was brought out in combination with a nitrification inhibitor. The incorporation of green manure crops notedly increased N₂O emissions. N₂O emission after the incorporation of legumes was especially high. In the container experiments, a diurnal rhythm of the N₂O and NH₃ flows in growing rape and vetch was observed. This indicated a stomatal flow of these gaseous nitrogen forms. N₂O emissions also occurred outside of the vegetation period at temperatures between 0 and 5°C, with the N₂O emissions from the nitrogen fertilized parcels being greater than the emissions from the unfertilized parcels. In container experiments, the N₂O emissions after freeze / thaw cycles were greater from white clover than from perennial rye grass. In fallow soil columns, the N₂O emissions after freeze / thaw cycles were especially high if the content of nitrate and water-soluble organic carbon in the soil was large. The results of this research show that the emission of nitrogen-containing compounds after organic and inorganic fertilization can be reduced through application methods (immediate incorporation), appropriate fertilization technology (addition of nitrification inhibitors), but also through fertilizer application under favourable weather conditions to include seasonal and volume adjustment of the fertilizer based on the growth requirements of the plants. Because high N₂O emissions can also occur at low temperatures, cultivation practices that influence the availability of mineral nitrogen and easily degradable organic substances in the soil during cold weather have a large impact on the N₂O emissions from agricultural land.
Regionale Darstellung der Umweltbelastungen durch klimarelevante Gase in der Agrarlandschaft Kraichgau - Das Boden-Landnutzungs-Informations-System für Treibhausgasemissionen
(2003) Rohierse, Andrea; Doluschitz, Reiner
Summary Goals The goals of the doctoral thesis were to determine at regional level the environmental impacts in the form of greenhouse gas emissions from the agricultural landscape of the Kraichgau region, to produce a method for projecting greenhouse gas emissions from agriculture and to subject appropriate prevention scenarios to an impact analysis. To attain these goals, a geographic information system (GIS) was used to build an environmental information system for greenhouse gases titled ?Soil and Land Use Information System for Greenhouse Gas Emissions?. Results Spatial presentation of the geodata bank Besides generation of a map of potential soil moisture for the Kraichgau region, the geodata basis developed here can be used to produce numerous thematic maps, such as fertilization maps and emissions maps of the greenhouse gases nitrous oxide and methane, as well as a map of the CO2 equivalent inventory. This can visualize the locations of centres of high or low emissions in the Kraichgau region. The findings of the evaluation of land-use maps generated from satellite images of the year 2000 show that the method of supervised classification used there and the multitemporal satellite image evaluation provide sufficient accuracy for a regional determination of greenhouse gas emissions from agriculture, as they were on average able to classify correctly 72% of arable land uses typical of the Kraichgau region. Forecast projection of greenhouse gas emissions from agriculture The environmental information system thus established allowed spatial quantification of Kraichgau-specific emissions. For this physiographic region, average total nitrous oxide emissions of 3.2 kg N2O-N / ha*a according to IPCC (2000b) were determined, taking the 22 Kraichgau municipalities into consideration. The average calculated maximum nitrous oxide emission potential from agriculturally utilized soils of the 2000 reference system at municipal level figures 4.1 kg N2O-N / ha*a, while the minimum figures 2.2 kg N2O-N / ha*a. Using Global Warming Potential (GWP) indexes, the CO2 equivalent inventory was calculated according to IPCC (2001) for the soils of the Kraichgau region. This was found to average 1.5 t CO2 equivalent / ha*a (GWP 100). The knowledge-based approach yielded a CO2 equivalent inventory around 1.1 t CO2 equivalent / ha*a (GWP 100). Overall, modelling found the Kraichgau physiographic region and arable farming region to represent a source of greenhouse gases. This was determined strongly by the high GWP of nitrous oxide compared to that of methane and carbon dioxide, and the circumstance that nitrogen inputs are relatively high in the intensively managed agricultural landscape. Impact analysis The results of the impact analysis show that if total nitrogen inputs are reduced by 20%, then some 6% of greenhouse gas emissions can be saved. If then, in land management, current fertilization guidance such as provided by the nitrate information service is complied with, this resulted in the GIS model in a roughly 10% reduction of CO2 equivalent emissions for the Kraichgau region. In a further prevention scenario, land uses were changed from intensively cultivated field crops (root crops) to extensively cultivated field crops or summer crops (malting barley), these being representative of other extensively cultivated crop varieties. At the same time, arable land was converted to low-intensity grassland areas, preferentially in zone III water protection zones. This reduced the CO2 equivalent inventory in the soil and land use system by about one third. Implementation of further measures and conversion of agriculturally utilized areas to organic management ? which, besides different fertilization practices, involves different cropping structures, a shift from short rotations to multiple rotations, and extensive grassland use ? even produce a reduction of greenhouse gas emissions by about two thirds in the model. The prevention scenarios ? involving reduced nitrogen inputs, compliance with current fertilization guidance across the whole region, and a range of land-use changes through to the conversion of farming practices to organic management ? show that climate protection goals can indeed be achieved in agriculture. This necessitates, besides reducing mineral as well as organic fertilizer inputs, changes in cropping structures, in rotations, in the choice of field crops as well as general changes to management methods and land-use changes. If this package of measures developed in the prevention scenarios were implemented in the production practices of farm holdings, with specific focuses depending upon the specific type of holding, climate protection in agriculture could be promoted greatly.
Untersuchungen zur Reduzierung der Ammoniakemissionen nach der Ausbringung von Rinderflüssigmist auf Grünland
(2000) Reitz, Petra; Kutzbach, Heinz Dieter
Ammoniakemissionen stammen zum Großteil aus der landwirtschaftlichen Tierhaltung etwa die Hälfte wird durch die Ausbringung von Flüssigmist verursacht. Unter ungünstigen Bedingungen kann der mit dem Flüssigmist ausgebrachte Ammonium-Stickstoff fast vollständig als NH3-Gas in die Atmosphäre emittieren. Negative Folgewirkungen sind die Verringerung des Düngewertes, eine ungesicherte Düngewirkung sowie nachhaltige Umweltschädigungen. Ziel der Untersuchungen war die Bestimmung der Einflussfaktoren auf die NH3-N-Emissionen nach der Ausbringung von Rinderflüssigmist auf Grünland. Es wurden verschiedene Witterungsbedingungen und verfahrenstechnische Maßnahmen wie Ausbringverfahren, Ausbringmenge und veränderte Zusammensetzung des Flüssigmistes untersucht.