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Emissions of nitrous oxide (N2O) from managed and grazed grasslands on peat soils are amongst the highest emissions in the world per unit of surface of agriculturally managed soil. According to the IPCC methodology, the direct N2O emissions from managed organic soils is the sum of N2O emissions derived from N input, including fertilizers, urine and dung of grazing cattle, and a constant ‘background’ N2O emission from decomposition of organic matter that depends on agro-climatic zone. In this paper we questioned the constant nature of this background emission from peat soils by monitoring N2O emissions, groundwater levels, N inputs and soil NO3 -–N contents from 4 grazed and fertilized grassland fields on managed organic peat soil. Two fields had a relatively low groundwater level (‘dry’ fields) and two fields had a relatively high groundwater level (‘wet’ fields). To measure the background N2O emission, unfertilized sub-plots were installed in each field. Measurements were performed monthly and after selected management events for 2 years (2008–2009). On the managed fields average cumulative emission equaled 21 ± 2 kg N ha-1y-1 for the ‘dry’ fields and 14 ± 3 kg N ha-1y-1 for the ‘wet’ fields. On the unfertilized sub-plots emissions equaled 4 ± 0.6 kg N ha-1y-1 for the ‘dry’ fields and 1 ± 0.7 kg N ha-1y-1 for the ‘wet’ fields, which is below the currently used estimates. Background emissions were closely correlated with groundwater level (R 2 = 0.73) and accounted for approximately 22% of the cumulative N2O emission for the dry fields and for approximately 10% of the cumulative N2O emissions from the wet fields. The results of this study demonstrate that the accuracy of estimating direct N2O emissions from peat soils can be improved by approximately 20% by applying a background emission of N2O that depends on annual average groundwater level rather than applying a constant value

Bodem beïnvloedt landgebruik maar het landgebruik zelf heeft ook effect op de bodem. Dit leidt tot een continue interactie tussen bodemgebruik, bodemkwaliteit en bodemfuncties. Recente veranderingen in landgebruik in Nederland en consequenties op bodemkwaliteit en bodemfuncties tonen de noodzaak voor een meer dynamische benadering van het begrip bodemkwaliteit aan

Dit project heeft als doel om de bestaande kennis van het gebruik van nitrificatieremmers onder Nederlandse omstandigheden te actualiseren en deze kennis te vertalen naar praktische mogelijkheden voor het gebruik van nitrificatieremmers bij de bemesting van grasland en bouwland in Nederlandse omstandigheden.

Intensively managed grasslands on organic soils are a major source of nitrous oxide (N2O) emissions. The Intergovernmental Panel on Climate Change (IPCC) therefore has set the default emission factor at 8 kg N–N2O ha-1 year-1 for cultivation and management of organic soils. Also, the Dutch national reporting methodology for greenhouse gases uses a relatively high calculated emission factor of 4.7 kg N–N2O ha-1 year-1. In addition to cultivation, the IPCC methodology and the Dutch national methodology account for N2O emissions from N inputs through fertilizer applications and animal urine and faeces deposition to estimate annual N2O emissions from cultivated and managed organic soils. However, neither approach accounts for other soil parameters that might control N2O emissions such as groundwater level. In this paper we report on the relations between N2O emissions, N inputs and groundwater level dynamics for a fertilized and grazed grassland on drained peat soil. We measured N2O emissions from fields with different target groundwater levels of 40 cm (‘wet’) and 55 cm (‘dry’) below soil surface in the years 1992, 1993, 2002, 2006 and 2007. Average emissions equalled 29.5 kg N2O–N ha-1 year-1 and 11.6 kg N–N2O ha-1 year-1 for the dry and wet conditions, respectively. Especially under dry conditions, measured N2O emissions exceeded current official estimates using the IPCC methodology and the Dutch national reporting methodology. The N2O–N emissions equalled 8.2 and 3.2% of the total N inputs through fertilizers, manure and cattle droppings for the dry and wet field, respectively and were strongly related to average groundwater level (R 2 = 0.74). We argue that this relation should be explored for other sites and could be used to derive accurate emission data for fertilized and grazed grasslands on organic soils

Managed grasslands are occasionally ploughed up and reseeded in order to maintain or increase the sward productivity. It has been reported that this renovation of grassland is associated with a flush of soil organic nitrogen (N) mineralization and with a temporary increase in soil mineral N contents. Here, we report on the effects of method and time of grassland renovation on herbage yield, nitrate (NO3 -) leaching and nitrous oxide (N2O) emission. Field experiments were carried out at three sites (two sandy soils and a clay soil) in the Netherlands for three years. Renovation of grassland increased the percentage of Perennial ryegrass from 48–70% up to more than 90%. However, averaged over three years, dry matter yields were higher for the reference (not reseeded) swards (on average 13.6 Mg ha-1 for the highest N application rate) than for the renovated grasslands (12.2–13.1 Mg ha-1 dry matter). Grassland renovation in April did not increase N leaching in comparison to the reference. However, renovation in September increased the risk of leaching, because mineral N contents in the 0–90 cm were in November on average 46–77 kg N ha-1 higher than in the reference. Contents of dissolved organic N (DON) in the soil were not affected by renovation. Renovation increased N2O emissions by a factor of 1.8–3.0 relative to the reference grassland. Emissions of N2O were on average higher after renovation in April (8.2 kg N2O-N ha-1) than in September (5.8 kg N2O-N ha-1). Renovation without ploughing (i.e. only chemically destruction of the sward) resulted in a lower percentage of perennial ryegrass (60–84%) than with ploughing (>90%). Moreover, N2O emissions were higher after renovation without ploughing than with ploughing. Clearly, farmers need better recommendations and tools for determining when grassland renovation has beneficial agronomic effects. Losses of N via leaching and N2O emission after renovation can probably not be avoided, but renovation in spring in stead of a

In many countries around the world impacts of climate change are assessed and adaptation options identified. We describe an approach for a qualitative and quantitative assessment of adaptation options to respond to climate change in the Netherlands. The study introduces an inventory and ranking of adaptation options based on stakeholder analysis and expert judgement, and presents some estimates of incremental costs and benefits. The qualitative assessment focuses on ranking and prioritisation of adaptation options. Options are selected and identified and discussed by stakeholders on the basis of a sectoral approach, and assessed with respect to their importance, urgency and other characteristics by experts. The preliminary quantitative assessment identifies incremental costs and benefits of adaptation options. Priority ranking based on a weighted sum of criteria reveals that in the Netherlands integrated nature and water management and risk based policies rank high, followed by policies aiming at 'climate proof' housing and infrastructure.

In many countries around the world impacts of climate change are assessed and adaptation options identified. We describe an approach for a qualitative and quantitative assessment of adaptation options to respond to climate change in the Netherlands. The study introduces an inventory and ranking of adaptation options based on stakeholder analysis and expert judgement, and presents some estimates of incremental costs and benefits. The qualitative assessment focuses on ranking and prioritisation of adaptation options. Options are selected and identified and discussed by stakeholders on the basis of a sectoral approach, and assessed with respect to their importance, urgency and other characteristics by experts. The preliminary quantitative assessment identifies incremental costs and benefits of adaptation options. Priority ranking based on a weighted sum of criteria reveals that in the Netherlands integrated nature and water management and risk based policies rank high, followed by policies aiming at ‘climate proof’ housing and infrastructure.

Het areaal veengronden is de afgelopen 25 jar sterk afgenomen. De snelheid van afname wordt beïnvloed door de grondwaterstansdiepte en het grondgebruik. Door de veranderingen in de bodemopbouw is de landelijke bodemkaart niet meer actueeel, waardoor beleidsmakers, planologen en gebiedsbeheerders op dit moment met achterhaalde bodemkundige gegevens werken. De tijd is rijp voor aangepaste bodemkaarten

A full account for carbon dioxide (CO2) and other greenhouse gas balance is presented for the Dutch forest and nature areas for 1990¿2002 at a Tier 2.5 level. The paper outlines how complex guidelines can be turned into a practical system, appropriate for a small country, making use of the best knowledge and data available. The net total sink of all processes of the forest and other nature terrains balance is very stable through time around an average of 1.74 million tonnes of CO2 per year. The sink is to a large extent determined by the growth of forest remaining forest, and the harvest taking place in there. Newly added processes in this new National System are significant as well, but they compensate each other. The sources from deforestation and nitrous oxide (N2O) emissions (around 900 ktonne CO2) are for two thirds compensated by the sinks from afforestation, dead wood, soil C changes due to land use changes, and trees outside the forest. The land use changes between 1990 and 2000 showed that The Netherlands has an annual deforestation of 2504 ha (0.7% of the forest area) and an afforestation of 3124 ha. Deforestation led in total over the 13 years of 1990¿2002 to an emission of 11.2 million tonne CO2 compensated by only 1.9 million tonne CO2 due to afforestation.

Fertiliser and manure application are important sources of nitrous oxide (N2O) emissions from agricultural soils. The current default IPCC emission factor of 1.0% is independent of the type of fertiliser and manure, and application time, method and rate. However, in the IPCC Tiered system it is possible to use more specific emission factors that better reflect the actual fertiliser and manure management in a given country or region. The first and primary aim of this study was to determine whether the combination of cattle slurry injection with fertiliser application, which is common practice in intensively managed grasslands in the Netherlands and neighbouring countries, warrants an adjusted emission factor. A second aim was to evaluate whether alternative emission factors, based on N uptake and N surplus, respectively, give more insight in the N2O emission rates of various fertilisation strategies. In a 2-year field experiment on sandy soil in the Netherlands we measured the annual N2O emission from grasslands receiving repeated simultaneous applications of fertiliser and cattle slurry. The N2O fluxes and N uptake by grass were measured from plots receiving calcium ammonium nitrate (CAN) at four application rates, either with or without additional application of liquid cattle slurry, applied through shallow soil injection. The average emission factor for fertiliser-only treatments was 0.15%. The annual N2O emissions were similar for treatments receiving only fertiliser or only cattle slurry. In the first experimental year, application of cattle slurry increased the emission factor for fertiliser to 0.35%, but the second year showed no effect of cattle slurry on the emission from fertiliser. With regard to the first objective, we conclude that these results do not conclusively justify an adjusted emission factor for combined application of fertiliser and cattle slurry. To minimise risks however, it is sensible to avoid simultaneous application of fertiliser and catt

In many ecosystems, the nutrient supply is an important factor that determines plant species composition. Plant species have developed different characteristics, which make them successful competitors in either nutrient-poor or more fertile environments. These plant characteristics could, in turn, have important consequences for soil fertility. The research described in this thesis set out to investigate different plant characteristics of species from habitats that differ in nitrogen availability, to assess their possible consequences for soil nitrogen mineralization. Compared to species from nutrient-poor habitats, species from fertile habitats were expected to stimulate the N mineralization because they produce larger quantities of rhizodeposits and litter, which decompose better.Overall, the results described in this thesis support this hypothesis. Plant species from high fertility habitats increased soil N mineralization more than species from low fertility habitats. Living plants of species from high fertility habitats produced more root biomass and consequently more rhizodeposits. Moreover, species from high fertility habitats had a shorter root lifespan than low fertility species. As a result, they added greater amounts of dead roots to the soil, but the decomposability of these dead roots was not related to the fertility of the habitat that they preferred. The effect of N availability on the plant characteristics studied was striking. When N supply decreased, root biomass declined, especially for the species from high fertility habitats, and as a result the rhizodeposition decreased. Moreover, for all species lower N supplies had a negative effect on rhizodeposit and dead root decomposition. Living plants stimulated dead root decomposition but the degree of stimulation depended on the C:N ratio of the decomposing roots. Overall, the differences in stimulation or inhibition of the N mineralization as a result of different levels of soil fertility seemed to be

In het kader van het reductieplan overige broeikasgassen (ROB) wordt de effectiviteit van mogelijke maatregelen bij de beperking van emissies bestudeerd. In deze systeemanalyse worden het huidige graslandbeheer en de omvang van herinzaai en andere vormen van graslandverbetering beschreven. Als gevolg van het scheuren en onderploegen van grasland worden relatief grote hoeveelheden organische stikstof gemineraliseerd. Dit leidt tot vorming van lachgas. Jaarlijks wordt 10% van het Nederlandse graslandareaal gescheurd en ingezaaid met gras of andere gewassen. De verliezen aan stikstof bij graslandverbetering bedragen 100 tot 300 kg N per hectare. De emissie van lachgas als direct gevolg van de omzetting en herinzaai van grasland is geschat met emissiefactoren die toegepast worden voor (indirecte en directe) emissies na toediening van mest, omdat specifieke emissiefactoren ontbreken. Deze jaarlijkse emissie in Nederland bedraagt tussen 1 en 1,5 miljoen ton CO2-equivalenten. Door autonome ontwikkelingen (mest- en nitraatrichtlijn en dalende productprijzen) en de toepassing van de voorgestelde gerichte maatregelen (ROB) zal de emissie kunnen afnemen met ongeveer 0,5-0,6 miljoen ton CO2-equivalenten per jaar ten opzichte van 1990. De omvangrijkste bijdrage kan worden geleverd door het verminderen of niet omzetten van oud, permanent grasland naar tijdelijk grasland en bouwland. Perspectiefvolle maatregelen zijn verder vermindering van het areaal van herinzaai, plaatselijke graslandverbetering, doorzaaien en graslandverbetering alleen in (voor)zomer toepassen, en beperken van opname van grasland in rotaties. Een toename van de biologische landbouw kan daarentegen leiden tot continuering van grasland in rotaties om voldoende stikstof te leveren gedurende de bouwlandperiode en emissies van lachgas.

Approximately 42% of the Dutch agricultural land is drained using tile drains. Of all Dutch soil types peat soils are responsible for the highest emission of nitrous oxide per unit of surface for agricultural land. The emission of nitrous oxide is characterized by its high spatial variability, to which the presence of tile drains may contribute. The objective of this study was to quantify the spatial variability due to drainage of peat soil on grassland