Browsing by Subject "Nitrifikationshemmstoff"

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Effects of nitrification inhibitors and application technique on trace gas fluxes from a maize field after cattle slurry fertilization
(2019) Herr, Christina; Müller, Torsten
In a time of climate change and against the background of intensive animal husbandry and biogas production in Germany, strategies for mitigation of greenhouse gas (GHG) release and Nitrogen (N) losses from silage maize production become increasingly important, especially for organic fertilizers. Consequently, the main objective of this study was to determine the height of GHG release from silage maize production on a medium textured soil which is typical for this region in Southwest Germany and to evaluate useful fertilization opportunities to mitigate carbon dioxide (CO2) footprint per yield unit. To identify management factors improving GHG budget from silage maize, annual nitrous oxide (N2O) and methane (CH4) measurements were carried out during maize growth and subsequent black fallow at least weekly. Investigations were conducted over two years on two adjacent fields (one for each study year). Amounts of ammonia (NH3) volatilizations after fertilization and nitrate (NO3-) leaching losses were also included in GHG balances. In dependence on available data, determined or estimated values were used. Additionally, yield and N removal from maize plants were quantified. The basic treatments of this study which investigated impact of fertilizer form and application techniques, were an unfertilized control (CON), a mineral fertilization (MIN), a banded cattle slurry application by trailing hose and subsequent incorporation (INC) and a cattle slurry injection (INJ). As confirmed repeatedly, in contrast to broadcast slurry incorporation, slurry injection efficiently reduced the risk of NH3 losses by direct slurry placement into the soil, but simultaneously provoked N2O formation more strongly, probably due to the anaerobic conditions in the injection slot favoring denitrification. For reducing N2O release from slurry injection, the applicability of six single or combined nitrification inhibitors (NIs) concerning potential GHG reduction were investigated. This N2O reduction should be reached through the desynchronized availability of carbon (C) and NO3-, derived from nitrified slurry ammonium (NH4+). Thus, in the period after slurry application, N2O losses from denitrification as well as from nitrification should be reduced through NIs. For final evaluation, collection of measured and estimated data (including direct and indirect N2O losses (NH3, NO3-), CH4 budget, pre-chain emissions from mineral fertilizer and fuel consumption) were converted into CO2 equivalents and summarized as area- or yield-related GHG balances. Except for one of the INJ treatments with NI (exclusively investigated in the first year) and one INC treatment with NI (exclusively investigated in the second year), all remaining treatments were tested in both experimental years. The height of NH3 emissions from INC treatment (12-23 % of applied NH4+-N) was more weather-dependent than those from INJ treatment (12-15 % of applied NH4+-N). In mean over both years, cumulative N2O emission from INJ treatment (13.8 kg N2O-N ha-1 yr-1), was significantly higher than from CON, MIN, and INC which recorded 2.8, 4.7, and 4.4 kg N2O-N ha-1 yr-1. NIs decreased the fertilization-induced N2O emissions from injection by 36 % (mean over all NIs and years) by an order of magnitude comparable to slurry incorporation. The NIs investigated tended to be categorized in inhibitors with prior and delayed inhibitory maximum. Whether low persistence, or poor biological degradability was an advantage, depended on environmental conditions. A combination of two NIs, one with putative prior and one with delayed release behavior reached the highest N2O reduction. In the additional INC treatment, this NI combination tended to reduce annual N2O release by 20 % in comparison to incorporation without inhibitor. Beside the potential of reducing fertilization-induced N2O emissions, NIs might also help to improve CH4 budgets in silage maize production. In general, CON, MIN and INC were net CH4 sinks in both years with mean uptakes of 460, 127, and 793 g CH4-C ha-1 yr-1, respectively. Conversely, slurry injection resulted in net CH4 emissions of 3144 g CH4-C ha-1 yr-1 (mean over both years). However, NIs tended to reduce CH4 emissions from injection by around 48 % and increased CH4 consumption from slurry incorporation by 20 %. Across all treatments and years, direct N2O emissions were the major contributor to total GHG balance. Yield-related GHG budgets from both years were lowest for CON, followed by INC or MIN treatment and significantly highest for sole slurry injection. NIs decreased fertilization-induced GHG release from injection in mean over both years by order of magnitude comparable with slurry incorporation. Consequently, alongside slurry incorporation and broadcast mineral fertilization, slurry injection combined with recommended NIs was evaluated as an equally appropriate fertilization strategy in terms of the atmospheric burden for livestock farmers.
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.