Atmosphärische Stickstoffeinträge in Hochmoore Nordwestdeutschlands und Möglichkeiten ihrer Reduzierung: Eine Fallstudie aus einer landwirtschaftlich intensiv genutzten Region

Der im deutsch-niederländischen Grenzgebiet liegende 'Internationale Naturpark Bourtanger Moor/Bargerveen' zeichnet sich durch zahlreiche noch verbliebene Moore aus, deren Lage inmitten einer landwirtschaftlich intensiv genutzten Region aufgrund der erhöhten Stickstoff (N)-Deposition aus der Atmosphäre eine zusätzliche Belastung für die durch Torfabbau und Wassermangel z.T. bereits stark degradierten Moorgebiete bildet. Aus den sehr unterschiedlichen Nutzungsansprüchen in dieser Region ergeben sich unvermeidliche Konflikte zwischen Landwirtschaft und Naturschutz, die in dieser Studie aufgegriffen wurden. Gemessene Jahresmittelwerte der Ammoniak (NH3)-Konzentrationen auf den Hochmoorflächen von 3,9 bis 5,6 μg m-3 lagen auf dem Niveau landwirtschaftlich intensiv genutzter Räume. Eine effektive abschirmende Wirkung haben die an und in den Mooren vorkommenden Gehölzreihen mit einer Minderungswirkung von 14-18 %. Mit insgesamt sechs weitgehend unabhängigen Verfahren wurden N-Depositionen von 21 bis 25 kg ha-1 a-1 ermittelt. Damit sind die Critical Loads, welche für die untersuchten Hochmoortypen bei etwa 5 bis 10 kg ha-1 a-1 liegen, deutlich überschritten. Die innerhalb des Untersuchungsgebietes freigesetzten NH3-Emissionen tragen zu einem Anteil von 23 % zur Stickstoffbelastung bei, etwa 7 % stammen aus deutschen und 1 % aus niederländischen Ställen. Mit 13 % wird der größte Beitrag durch die Ausbringung von Wirtschaftsdüngern (Gülle) und Gärsubstraten von deutschen landwirtschaftlichen Flächen freigesetzt. Deutlich geringer ist der niederländische Anteil von 1,6 %. Dies ist sowohl auf den verstärkten Einsatz emissionsmindernder Ausbringungstechniken als auch auf den deutlich niedrigeren Flächenanteil im Untersuchungsgebiet zurückzuführen. 77 % der N-Depositionen gelangen über den Ferntransport in die Moore des Untersuchungsgebietes. Auch die N-Deposition über Ferntransport stammte überwiegend aus NH3-Emissionen der Landwirtschaft. In einem Szenario wurde unter Berücksichtigung aller technischen Möglichkeiten (teilweise zurzeit nur in den Niederlanden gebräuchlicher Verfahren) zur Abluftreinigung und Gülleausbringung eine maximale Minderung der NH3-Emissionen im Untersuchungsgebiet von 64 % berechnet. Das größte Minderungspotenzial von ca. 2 kg ha-1 a-1 Depositionsminderung besitzt die Ausbringung von Wirtschaftsdüngern mittels Injektionsverfahren. Die Ergebnisse verdeutlichen, dass regionale NH3-Minderungskonzepte alleine nicht ausreichend sind, um die untersuchten Moorgebiete vor schädlichen Stickstoffeinträgen zu schützen. Regionale Emissionsminderungskonzepte sollten daher in umfassende nationale und internationale Strategien zur Minderung der NH3-Emissionen aus der Landwirtschaft eingebunden werden.The 'International Nature Park Bourtanger Moor/Bargerveen' located at the German-Dutch border region is characterized by numerous remaining raised bogs within an intensively managed agricultural landscape and is thereby subjected to elevated nitrogen (N) deposition from the atmosphere. This situation leads to unavoidable conflicts of interest between agriculture and nature conservation, which are being investigated in this study. Measured annual means of ammonia (NH3) concentrations at the study sites were between 3.9 and 5.6 μg m-3, thus on the same level as values for arable sites. Grove lines form an effective protection against NH3 dispersion with a mitigation potential of 14-18 %. N deposition was determined by six independent methods and was found to be in a range from 21 to 25 kg ha-1 yr-1. These results show that bog-specific critical loads of 5 to 10 kg ha-1 yr-1 were clearly exceeded. NH3 emissions from the study area contribute 23 % to the overall nitrogen load that is locally deposited. 7 % and 1 % originate from German and Dutch stables, respectively. While the highest share of 13 % is released through the application of farm fertilizer (slurry) and fermented substrate from German arable land, only 1.6 % is emitted from Dutch sites mainly due to more efficient low-emission techniques and the smaller Dutch part of the study site compared to the German part. 77 % of the overall N deposition into the peatlands of the study area originates from non-local - but nevertheless agricultural - sources with the nitrogen being transported over long distances. A maximum reduction of NH3 emissions within the study area under consideration of all technical capabilities for waste air quality control and slurry application (some of them currently only used in the Netherlands) were found to be 64 %. Deposition can be reduced by ca. 2 kg ha-1 yr-1 through injection of fertilizer into the soil. The results show that regional NH3 mitigation concepts are not sufficient to protect the studied peatland sites against harmful excess nitrogen loads. Thus, regional concepts should be integrated into comprehensive national and international strategies to achieve an effective reduction of NH3 emissions from agricultural activities

A decision support system for the integrated evaluation of agricultural management on environmental quality

ABSTRACT Excess nitrogen inputs by animal manure and fertilizer in the Netherlands do cause various effects, such as (i) decreased plant species diversity of terrestrial ecosystems by eutrophication and acidification induced by elevated N deposition, (ii) decreased water quality and species diversity of aquatic ecosystems and eutrophication of coastal systems, mainly induced by runoff of N, (iii) high NO 3 concentrations in groundwater, used as drinking water with potential health impacts and (iv) elevated N 2 O emissions causing climate change. Apart from N emissions, excessive manure inputs also cause emissions of other greenhouse gases, mainly methane (CH 4 ), and accumulation and/or elevated leaching of various compounds to ground water and surface water. This paper presents an overview of the integrated model system IMITATOR predicting: (i) emissions of ammonia and greenhouse gases (CO 2 , CH 4 and N 2 O) from animal housing systems, agricultural land and drained peat lands and (ii) accumulation and leaching and runoff of carbon, nutrients (nitrogen, phosphate and base cations) and metals from agricultural soils to ground water and surface water. Results of various mitigation measures in view of reducing emissions of nitrogen compounds to air, ground water and surface water, including improved farming practices and structural changes in agriculture, do have a positive spinoff on the emissions or accumulation of other compounds as illustrated in the paper

Quantifying nitrogen fluxes and their influence on the greenhouse gas balance: recent findings of the NitroEurope Integrated Project

The generation of reactive nitrogen (Nr) by human activities to stimulate agricultural productivity and the unintended formation of Nr in combustion processes both have major impacts on the global environment. Effects of excess Nr include the deterioration of air quality, water quality, soil quality and a decline in biodiversity. One of the most controversial impacts of nitrogen, however, is on the greenhouse gas balance. While recent papers have highlighted a possible benefit of nitrogen in enhancing rates of carbon sequestration, there remain many trade-offs between nitrogen and greenhouse gas exchange. The result is that the net effect of Nr on the global radiative balance has yet to be fully quantified. To better understand these relationships requires intense measurement and modelling of Nr fluxes at various temporal and spatial scales in order to make the link between different nitrogen forms and their fate in the environment. It is essential to measure fluxes for a wide range of ecosystems considering the biosphere-atmosphere exchange of the Nr components and greenhouse gases, as well as the fixation of di-nitrogen and its creation by denitrification. Long-term observations are needed for representative ecosystems, together with results from experiments addressing the responses of the key nitrogen and greenhouse gas fluxes to different global change drivers. The NitroEurope Integrated Project (in short NEU IP), funded under the 6th Framework Programme of the European Commission, has developed and applied a strategy for quantifying these different terms on multiple scales. With the project nearing completion, this presentation reports selected preliminary findings. It highlights the first estimates of Nr inputs and net green-house gas exchange for a series of 13 flux ‘supersites’, complemented by the emerging results of Nr concentrations and related N inputs at a network of 58 ‘inferential sites’, which extend the European representativity of the results. In addition, new low cost methods to measure nitrogen fluxes will be reported, which have been extensively tested at those sites. Results from this 3-tier flux network are underpinned by emerging findings from an extensive network of manipulation sites. A combination of modelling at plot, landscape and European scales is used to upscale the results. Finally the talk will illustrate how nitrogen mitigation techniques are being considered at the European scale, including an estimation of the scale of costs involved in simultaneously mitigating nitrous oxide, ammonia and nitrate losse

Effecten van landschapsinrichting in de gebiedsgerichte aanpak van de stikstofopgave in provincie Flevoland : Een verkenning naar effecten van landschapselementen in Flevoland op de stikstofdepositie op De Wieden en Weerribben, de Veluwe en het Naardermeer

Op het mogelijke effect van het aanbrengen van landschapselementen in de provincie Flevoland op de ammoniakdepositie op drie nabij de provincie Flevoland gelegen stikstofgevoelige Natura 2000-gebieden (De Wieden en Weerribben, Veluwe en Naardermeer) is een literatuurstudie gedaan en is een aantal indicatieve modelberekeningen uitgevoerd. Hierbij zijn voor de provincie Flevoland effecten van verschillende varianten van landschapselementen op de ammoniakdepositie op de drie Natura 2000-gebieden doorgerekend met de modellen INITIATOR en OPS. Hoewel er vrij extreme scenario’s zijn gehanteerd, zijn de te behalende reducties in depositie zijn relatief klein en sterk afhankelijk van de lokale omstandigheden

Verkenning naar ruimtegebruik landbouw 2050 voor Regio Amersfoort : Regionale ruimtelijke uitwerking van WUR-scenariostudie Landbouw in Nederland in 2050 voor Regio Amersfoort

In deze studie zijn vier scenario’s uit de landelijke WUR-studie ‘Scenariostudie perspectief voor ontwikkelrichtingen Nederlandse landbouw in 2050’ (Lesschen et al., 2020) vertaald naar effecten op grondgebruik en veestapel in Regio Amersfoort. In deze regio is de gronddruk al hoog en vanuit verschillende hoeken worden er in de toekomst meer claims gelegd op het agrarische landelijk gebied. De agrarische sector zelf werkt echter ook aan de transitie van het voedselsysteem en aan de hand van de vier scenario’s wordt inzichtelijk gemaakt hoe het toekomstige ruimtegebruik voor de landbouw in Regio Amersfoort eruit kan zien gegeven de opgaven waar de landbouw op dit moment voor staat.De resultaten laten zien dat de transitie van de landbouw ook veel ruimte vergt en dat de behoefte aan grond voor deze sector in de toekomst ook groot blijft

Bayesian calibration of the VSD soil acidification model using European forest monitoring data

Over the past years, Bayesian calibration methods have been successfully applied to calibrate ecosystem models. Bayesian methods combine prior probability distributions of model parameters, based on assumptions about their magnitude and uncertainty, with estimates of the likelihood of the simulation results by comparison with observed values. Bayesianmethods also quantify the uncertainty in the updated posterior parameters,which can be used to perform an analysis of model output uncertainty. In this paper, we applied Bayesian techniques to calibrate the VSD soil acidification model using data from182 intensively monitored forest sites in Europe. Out of these 182 plots,122 plotswere used to calibrate VSD and the remaining 60 plots to validate the calibratedmodel. Prior distributions for the model parameters were based on available literature. Since the available literature shows a strong dependence of some VSD parameters on, for example, soil texture, prior distributions were allowed to depend on soil group (i.e. soils with similar texture or C/N ratio). The likelihood was computed by comparing modelled soil solution concentrations with observed concentrations for the period 1996–2001. Markov Chain Monte Carlo (MCMC) was used to sample the posterior parameter space. Two calibration approacheswere applied. In the single-site calibration, the plotswere calibrated separately to obtain plot-specific posterior distributions. In themulti-site approach priorswere assumed constant in space for each soil group, and all plotswere calibrated simultaneously yielding one posterior probability distribution for each soil group. Results fromthe single-site calibrations showthat themodel performedmuch better after calibration compared to a run with standard input parameters when validated on the 60 validation plots. Posterior distributions for H-Al equilibrium constants narrowed down, thus decreasing parameter uncertainty. For base cation weathering of coarse textured soils the posterior distribution shifted to larger values, indicating an initial underestimation of the weathering rate for these soils. Results for the parameters related to nitrogenmodelling showed that the nitrogen processes model formulations in VSD may have to be reconsidered as the relationship between nitrogen immobilization and the C/N ratio of the soil, as assumed in VSD, was not substantiated by the validation. The multi-site calibration also strongly decreasedmodel error formostmodel output parameters, butmodel errorwas somewhat larger than themedianmodel error fromthe single-site calibration except for nitrate. Because the large number of plots calibrated at the same time provided very many observations, theMarkov Chain converged to a very narrowparameter space, leaving little room for posterior parameter uncertainty. For an uncertainty analysis with VSD on the European scale, this study provides promising results, but more work is needed to investigate howthe results can be used on a European scale by looking at regional patterns in calibrated parameters fromthe site calibration or by calibrating for regions instead of all of Europe