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Circulaire landbouw is volhoudbaar als aan- en afvoer van nutriënten goed op elkaar zijn afgestemd en de bodemkwaliteit wordt gehandhaafd en verbeterd. Het vereist niet alleen maximale inzet van reststromen, maar ook de juiste inzet van minerale meststoffen. Vakmanschap van de agrarische ondernemer is daarbij cruciaal.

Sustainable soil carbon sequestration practices need to be rapidly scaled up and implemented to contribute to climate change mitigation. We highlight that the major potential for carbon sequestration is in cropland soils, especially those with large yield gaps and/or large historic soil organic carbon losses. The implementation of soil carbon sequestration measures requires a diverse set of options, each adapted to local soil conditions and management opportunities, and accounting for site-specific trade-offs. We propose the establishment of a soil information system containing localised information on soil group, degradation status, crop yield gap, and the associated carbon-sequestration potentials, as well as the provision of incentives and policies to translate management options into region- and soil-specific practices.

This chapter steps back from specific empirical cases and discusses alternative theoretical lenses that can be used to study if and how blockchain-based registries in Africa will be affecting organizations and society. Those lenses are: Neoinstitutionalism, Structuration theory, and Actor-Network theory. Each of them is adopted to outline aspects of blockchain first, then to highlight specificities in Ghana, finally to suggest research lines. This plurality of theoretical lenses encourages to foster a more nuanced understanding of unconventional contexts of technology in use, thus to derive better recommendations than those based on reductionist frameworks, which often overlook specificities of developing countries.

"The effects of atmospheric nitrogen deposition (N-dep) on carbon (C) sequestration in forests have often been assessed by relating differences in productivity to spatial variations of N-dep across a large geographic domain. These correlations generally suffer from covariation of other confounding variables related to climate and other growth-limiting factors, as well as large uncertainties in total (dry + wet) reactive nitrogen (N-r) deposition. We propose a methodology for untangling the effects of N-dep from those of meteorological variables, soil water retention capacity and stand age, using a mechanistic forest growth model in combination with eddy covariance CO2 exchange fluxes from a Europe-wide network of 22 forest flux towers. Total N-r deposition rates were estimated from local measurements as far as possible. The forest data were compared with data from natural or semi-natural, non-woody vegetation sites. The response of forest net ecosystem productivity to nitrogen deposition (dNEP/dN(dep)) was estimated after accounting for the effects on gross primary productivity (GPP) of the co-correlates by means of a meta-modelling standardization procedure, which resulted in a reduction by a factor of about 2 of the uncorrected, apparent dGPP/dN(dep) value. This model-enhanced analysis of the C and N-dep flux observations at the scale of the European network suggests a mean overall dNEP/dN(dep) response of forest lifetime C sequestration to N-dep of the order of 40-50 g C per g N, which is slightly larger but not significantly different from the range of estimates published in the most recent reviews. Importantly, patterns of gross primary and net ecosystem productivity versus N-dep were non-linear, with no further growth responses at high N-dep levels (N-dep > 2.5-3 gNm(-2) yr(-1)) but accompanied by increasingly large ecosystem N losses by leaching and gaseous emissions. The reduced increase in productivity per unit N deposited at high N-dep levels implies that

Is het nu wel of niet een goed idee om groenafval van bermen, natuurgebieden en sloten op te brengen op landbouwpercelen? Het lijkt een simpele vraag, maar het beantwoorden ervan is niet eenvoudig. Dit artikel geeft een kritische evaluatie van het gebruik van deze reststromen in het perspectief van kringlooplandbouw.

Humanity's transformation of the nitrogen cycle has major consequences for ecosystems, climate and human health, making it one of the key environmental issues of our time. Understanding how trends could evolve over the course of the 21st century is crucial for scientists and decision-makers from local to global scales. Scenario analysis is the primary tool for doing so, and has been applied across all major environmental issues, including nitrogen pollution. However, to date most scenario efforts addressing nitrogen flows have either taken a narrow approach, focusing on a singular impact or sector, or have not been integrated within a broader scenario framework – a missed opportunity given the multiple environmental and socio-economic impacts that nitrogen pollution exacerbates. Capitalizing on our expanding knowledge of nitrogen flows, this study introduces a framework for new nitrogen-focused narratives based on the widely used Shared Socioeconomic Pathways that include all the major nitrogen-polluting sectors (agriculture, industry, transport and wastewater). These new narratives are the first to integrate the influence of climate and other environmental pollution control policies, while also incorporating explicit nitrogen-control measures. The next step is for them to be used as model inputs to evaluate the impact of different nitrogen production, consumption and loss trajectories, and thus advance understanding of how to address environmental impacts while simultaneously meeting key development goals. This effort is an important step in assessing how humanity can return to the planetary boundary of this essential element over the coming century.

Sustainable soil carbon sequestration practices need to be rapidly scaled up and implemented to contribute to climate change mitigation. We highlight that the major potential for carbon sequestration is in cropland soils, especially those with large yield gaps and/or large historic soil organic carbon losses. The implementation of soil carbon sequestration measures requires a diverse set of options, each adapted to local soil conditions and management opportunities, and accounting for site-specific trade-offs. We propose the establishment of a soil information system containing localised information on soil group, degradation status, crop yield gap, and the associated carbon-sequestration potentials, as well as the provision of incentives and policies to translate management options into region- and soil-specific practices.

Plant species occurrence in Europe is affected by changes in nitrogen deposition and climate. Insight into potential future effects of those changes can be derived by a model approach based on field-based empirical evidence on a continental scale. In this paper, we present a newly developed empirical model PROPS, predicting the occurrence probabilities of plant species in response to a combination of climatic factors, nitrogen deposition and soil properties. Parameters included were temperature, precipitation, nitrogen deposition, soil pH and soil C/N ratio. The PROPS model was fitted to plant species occurrence data of about 800,000 European relevés with estimated values for pH and soil C/N ratio and interpolated climate and modelled N deposition data obtained from the Ensemble meteo data set and EMEP model results, respectively. The model was validated on an independent data set. The test of ten species against field data gave an average Pearson's r-value of 0.79. PROPS was applied to a grassland and a heathland site to evaluate the effect of scenarios for nitrogen deposition and climate change on the Habitat Suitability Index (HSI), being the average of the relative probabilities, compared to the maximum probability, of all target species in a habitat. Results for the period 1930–2050 showed that an initial increase and later decrease in nitrogen deposition led to a pronounced decrease in HSI, and with dropping nitrogen deposition to an increase of the HSI. The effect of climate change appeared to be limited, resulting in a slight increase in HSI.

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Taak van het adviescollege was om te beoordelen of de huidige meet- en rekensystematiek voor stikstofemissie en -depositie voldoende wetenschappelijke onderbouwing biedt voor het stikstofbeleid. In de eerste fase keek het adviescollege naar de algemene inrichting van de meet- en rekensystematiek. In de tweede fase werkte het adviescollege, waar nodig, de eerste bevindingen verder uit en besteedde daarnaast bijzondere aandacht aan NEMA (voor de bepaling van de landbouwemissies) en AERIUS Calculator als toetsingsinstrument bij vergunningverlening.

Het Adviescollege Meten en Berekenen Stikstof is in december 2019 begonnen aan de eerste fase van zijn opdracht om advies te geven over de wetenschappelijke kwaliteit van de Nederlandse systematiek voor het meten van en rekenen aan stikstofverbindingen ter onderbouwing van het (toekomstig) beleid van de Rijksoverheid en provincies. Het uitgangspunt was de vraag: zijn de data, methoden en modellen die worden ingezet van voldoende wetenschappelijke kwaliteit en daarmee doelgeschikt?

Momenteel is de vergunningverlening gebaseerd op een toelaatbare toename van de stikstof-depositie op een nabijgelegen natuurgebied. Dat beleid is ingewikkeld en om meer redenen niet optimaal. Het is zinvol om de focus te verleggen van lokaal depositiebeleid naar meer generiek emissiebeleid, met daarin opgenomen het realiseren van een nationaal emissieplafond in 2030 en 2050. Dit sluit aan op de systematiek van het klimaatakkoord en is bestuurlijk en juridisch beter te verdedigen. Het haalt bovendien de overmatige aandacht weg van economische activiteiten rondom Natura 2000-gebieden en zal positief uitpakken voor de natuur.