J.C.H. Voogd

Impacts of model structure and data aggregation on European wide predictions of nitrogen and green house gas fluxes in response to changes in livestock, land cover, and land management

Various model approaches have been developed for assessing emissions of different forms of reactive nitrogen in various parts of Europe at various geographic resolutions and for various time periods. The modeling approaches include emission factor approaches, empirical models, simple process-based models, and detailed ecosystem models. In this study, we compared three relatively simple process-based models, developed for the national scale (Integrated NITrogen Impact AssessmenT model On a Regional Scale (INITIATOR2)), European scale (MITERRA) and global scale (integrated model to assess the global environment (IMAGE)), with respect to their response to structural and technological changes in the agricultural systems based on the IPCC B2 baseline scenario for the period 2000–2030. Changes are predicted by the IMAGE model and relate to crop yield, crop area, animal numbers, and N fertilizer inputs. The predicted relative changes by IMAGE are used in INITIATOR2 and MITERRA while relating the animal categories and crop categories in IMAGE to those in the latter models. A comparison was made of NH3, N2O and NO x emissions and N leaching to ground water. We compared predictions for the years 2000 and 2030 for: (i) the Netherlands between INITIATOR2 and MITERRA and (ii) Europe (EU-27 countries) between MITERRA and IMAGE. The results of the comparison are presented and evaluated in view of differences in model structure and the effect of aggregating input data at larger spatial scales.

Assessment of critical loads and their exceedance on Dutch forests using a multi-layer steady-state model

Critical acid loads for Dutch forests were derived using a multi-layer steady-state model that includes canopy interactions, nutrient cycling, mineral weathering and N transformations. Values were calculated for combinations of 12 tree species and 23 soil types for a 10×10 km grid. Critical acid loads thus derived increased with decreasing soil depth. Nearly 90% of the values varied approximately between 1500 and 4000 molc ha−1 yr−1 at 10 cm soil depth and between 750 and 2000 molc ha−1 yr−1 at the bottom of the rootzone. Separate critical loads calculated for N and S at the bottom of the rootzone varied between approximately 300 and 1000 molc ha−1 yr−1 for N and between 150 and 1250 molc ha−1 yr−1 for S. Using deposition data of 1990, a median reduction of the deposition by approximately 75% was calculated to achieve the critical loads at the bottom of the rootzone. The overall uncertainty in this value was estimated to be about 10%, although it can be much larger for specific soil types such as clay and peat soils. For N a larger reduction deposition percentage was calculated than for S, especially for coniferous forests with a high present N input.

Soil and Soil Solution Composition of 150 Forest Stands in the Netherlands in 1990

Publisher Summary During the period March to May 1990, the chemical composition of the humus layer, the mineral topsoil (0–30 cm), and the mineral subsoil (60–100 cm) has been determined for 150 forest stands. All stands were part of the national forest vitality inventory. They were all located on noncalcareous sandy soils. Tree species included were Scotch Pine, Black Pine, Douglas Fir, Norway Spruce, Japanese Larch, Oak, and Beech. Measurements for the humus layer and mineral topsoil included total contents of C, N, and P and exchangeable contents of H, Al, Fe, Ca, Mg, K, Na, and NH. Soil solution measurements in the mineral soil included the cations mentioned before and NO, SO, C1, HCO, and DOC. An important aim of the research was to assess the effect of deposition levels, tree species, and site characteristics on the level of A1 mobilization (acidification) and N accumulation (eutrophication) in the soil. Important characteristics of the chemical composition of the humus layer and mineral topsoil are presented.

Critical Loads for Dutch Forest Soils

Abstract Critical loads for N and S on Dutch forests have been derived by using simple steady-state models. Critical loads have been calculated for combinations of 12 tree species and 23 soil types for a 10 × 10 km grid. Values thus derived varied between approximately 300 and 1000 molc ha−1 yr for N and between 150 and 1250 molc ha−1 yr−1 for S. Amounts by which the critical loads are exceeded varied between approximately 1200 and 6100 molc ha−1 yr−1 for N and between 850 and 2900 molc ha−1 yr−1 for S, using deposition data based on 1985 emissions. The excess in critical N loads was much less for deciduous forests than for coniferous forests. For S the difference between coniferous and deciduous forests was quite small. A median reduction of approximately 80% will be needed to approach the critical loads for forest in the Netherlands.

A comparison of disaggregated nitrogen budgets for Danish agriculture using Europe-wide and national approaches

Spatially detailed information on agricultural nitrogen (N) budgets is relevant to identify regions where there is a need for a reduction in inputs in view of various forms of N pollution. However, at the scale of the European Union, there is a lack of consistent, reliable, high spatial resolution data necessary for the calculation of regional N losses. To gain insight in the reduction in uncertainty achieved by using higher spatial resolution input data. This was done by comparing spatially disaggregated agricultural N budgets for Denmark for the period 2000-2010, generated by two versions of the European scale model Integrator, a version using high spatial resolution national data for Denmark (Integrator-DK) and a version using available data at the EU scale (Integrator-EU). Results showed that the national N fluxes in the N budgets calculated by the two versions of the model were within 1-5% for N inputs by fertilizer and manure excretion, but inputs by N fixation and N mineralisation differed by 50-100% and N uptake also differed by ca 25%, causing a difference in N leaching and runoff of nearly 50%. Comparison with an independently derived Danish national budget appeared generally to be better with Integrator-EU results in 2000 but with Integrator-DK results in 2010. However, the spatial distribution of manure distribution and N losses from Integrator-DK were closer to observed distributions than those from Integrator-EU. We conclude that close attention to local agronomic practices is needed when using a leaching fraction approach and that for effective support of environmental policymaking, Member States need to collect or submit high spatial resolution agricultural data to Eurostat.

Impact of cadmium levels in fertilisers on cadmium accumulation in soil and uptake by food crops

Cadmium (Cd) and other heavy metals (lead (Pb), arsenic (As), chromium (Cr) and zinc (Zn)) occur naturally in fertilisers but at variable levels. To determine whether or not levels of metals in fertiliser affect the absorption of Cd and other metals by agricultural crops, a greenhouse study was performed to measure the uptake of Cd and other metals from 7 different soils grounds treated with either mineral fertiliser with increasing levels of Cd and one type of animal manure (cattle manure). The results show that there is no significant difference in absorption of Cd nor on other metals when P fertiliser is used with levels of Cd varying between 0.04 and 60 mg Cd kg-1 P2O5. Differences in soil properties (e.g. acidity and organic matter content) in combination with the content of Cd in the soil control the short term (1 harvest cycle) variation of Cd concentrations in crops. Long-term (100 years) calculations on a field and regional scale, however, show that the content of Cd in P fertilisers does affect both levels in soil and that in crops. Dynamic model simulations at EU level indicate that accumulation of Cd in soil (arable and grassland) continues if the Cd content in P fertilisers exceeds 20 mg Cd kg-1 P2O5. The calculated average long-term relative changes in both soil and arable crops relative to current levels are in the order of magnitude of +0.2% if no more Cd is applied via P fertiliser to 12.1% to 16% if, at the European level the concentration of Cd in mineral P-fertilisers averages 60 or 80 mg Cd kg-1 P2O5 respectively.

Long-Term Impact of Three Deposition Scenarios on Dutch Forest Soils

Publisher Summary The long-term impact of three deposition scenarios on Dutch forest soils has been evaluated using the regional soil acidification model (RESAM). RESAM describes changes in the chemical composition of the soil solid phase (minerals and adsorption complex) and soil solution due to natural and man-induced processes. The model is part of the overall Dutch acidification system (DAS) model. The regional application of RESAM has been restricted to 7 tree species and 14 noncalcareous sandy soils covering about 65% of the Dutch forest area. Deposition scenarios for total acidity (SO 2 , NO, and NH) have been generated by the DAS air transport model for the period 1990 to 2050 based on expected emissions in the near future (1990–2000) and deposition targets (2000–2050).