Bodemverdichting in Vlaanderen : Gevolgen van bodemverdichting op het watertransport door een bodem

De gevolgen van bodemverdichting op het watertransport door een bodem zijn verkend. Een bodemfysische database is gecreëerd door naast historische metingen nieuwe metingen te verzamelen op verdichte percelen. Dat is gebeurd door op 26 percelen op 2 plekken op 3 diepten ongestoorde monsters te nemen en de bodemfysische eigenschappen te bepalen. Op 6 percelen zijn continue hydrologische metingen verricht van bodemvocht op 3 diepten en grondwaterstanden. De laatste metingen zijn gebruikt om te toetsen of het model SWAP met de gemeten bodemfysische eigenschappen in staat is het watertransport in het perceel te beschrijven. Met SWAP zijn voor 5 Vlaamse stroomgebiedjes de effecten van bodemverdichting verkend voor klimaatscenario’s door de verdichte en niet-verdichte toestand te vergelijken. De met de pedotransferfuncties en nieuwe data berekende effecten van verdere verdichting op de waterhuishouding blijken globaal gezien beperkt te zijn. Dit neemt niet weg dat de lokale effecten mogelijk aanzienlijk kunnen zijn, gelet op de grote variatie in bodemverdichting die binnen de percelen werd opgemeten. De verschillen tussen de verdichte en niet-verdichte situatie in stroomgebieden zijn beperkt. Klimaatscenario’s leiden op verdichte bodems tot meer oppervlakkige afstroming en meer droogtegevoelighei

Life satisfaction, ethnicity and neighbourhoods: Is there an effect of neighbourhood ethnic composition on life satisfaction?

Immigrants and ethnic minorities tend to have lower life satisfaction than majority populations. However, current understanding of the drivers of these gaps is limited. Using a rich, nationally representative data set with a large sample of ethnic minorities and matched neighbourhood characteristics, we test whether first and second generation minorities experience lower life satisfaction once accounting for compositional differences and whether, specifically, neighbourhood deprivation impacts their wellbeing. We further investigate whether a larger proportion of own ethnic group in the neighbourhood improves satisfaction. We find life satisfaction is lower among ethnic minorities, and especially for the second generation, even controlling for individual and area characteristics. Neighbourhood concentration of own ethnic group is, however, associated with higher life satisfaction for Black Africans and UK born Indians and Pakistanis. The effect for Black Africans may stem from selection into areas, but findings for Indians and Pakistanis are robust to sensitivity tests

Visual assessment of soil structural quality across soil textures and compaction levels – Part II: Examination of profile walls vs Intact soil cores

Visual Evaluation of Soil Structure (VESS) methods receive increasing attention and are gaining popularity. Since in modern agriculture, soil structure degradation becomes very common, it is essential to protect and improve soil structure quality. Methods that enable its straightforward monitoring are therefore needed. Numerous visual soil evaluation techniques that serve this purpose exist, and are varying in objective, evaluation depth (topsoil/subsoil), evaluation method, number of criteria assessed and their final scoring. In this study, we mainly focus on three VESS methods, two of which were employed in the field along a profile wall (Visual Evaluation of Subsoil Structure, SubVESS, and Double Spade VESS method, DSVESS), and one in the laboratory on soil cores (CoreVESS). The main aim of this research was to test and compare these VESS-based methods in terms of their feasibility and repeatability in detecting soil structure degradation in the topsoil and subsoil. Sixteen cropped fields were chosen in Belgium covering six of seven major soil texture classes according to the Belgian soil textural triangle (i.e., sand, loamy sand, light sandy loam, silt loam, clay, and heavy clay). SubVESS and DSVESS were performed in the same pits until 80 cm and 40 cm, respectively. Soil cores for CoreVESS and for the determination of soil quality indicators (SQi) with conventional laboratory methods were taken from three layers, that is, the ploughed topsoil (∼10–∼20 cm, “TOP”), the compacted subsoil (∼30–∼40 cm, “CSUB”), and the deeper subsoil (∼60–∼70 cm, “SUB”), totalling 96 horizons. While SubVESS and CoreVESS were originally developed to evaluate subsoil and topsoil, respectively, they were thus used here beyond those zones. Moreover, all sampling and field evaluation was done at two positions per field - the more compacted headland and the less compacted in-field zone. It was shown that the soil quality (Sq) scores assigned to the cores with CoreVESS were not significantly influenced by operators with different backgrounds but all having received basic VESS training. When comparing field and laboratory results, positive relationships were found between Sq scores of SubVESS, DSVESS and CoreVESS. All VESS methods were able to assign significantly better soil quality (lower scores) at in-field positions (IN-FIELD) as compared to headland positions (HEAD), and significantly lower quality (higher scores) to CSUB layers than to the other two layers. Laboratory-derived SQi values presented a similar trend, with CSUB layers always indicating worse situations. There were good significant relationships between the SQi values and the different VESS-based Sq scores as well, with DSVESS showing the best correlations among the three VESS methods. The study thus confirmed that the different VESS methods all have a potential for monitoring soil structure quality in a fast, cheap, intuitive and practical way, although they all have their own advantages and disadvantages. Additionally, those methods that were employed at depths other than those for which they were developed did perform well

Visual assessment of soil structural quality across soil textures and compaction levels – Part I : Examination of intact soil cores

Soil structural degradation has become very common and leads to a serious decline in soil health. Improving or maintaining soil structure is key to build resilience against drought and flooding, and thus contributes to assuring food and water security. Quantification of soil structural quality is usually accomplished by traditional laboratory-based methods, which are time-, labour- and money-consuming. Visual soil evaluation and examination methods comprise rapid and simple tests that offer a numeric semi-quantitative assessment of soil structure. The common criteria are aggregate size and shape, ease of break or rupture resistance, and inter- or intra-aggregate porosity. In this study, the CoreVESS method, a variant of the Visual Evaluation of Soil Structure (VESS) method originally developed for topsoil assessment, was applied on 250 cm3 undisturbed soil core samples. Resulting soil quality scores (Sq, ranging between 1, good, and 5, poor) were compared with soil quality indicators (SQi) derived from traditional quantitative methods of soil structure analysis. Tested SQi's included penetration resistance, bulk density, soil hydraulic properties, soil organic carbon and texture (percentage of clay, silt and sand). The objective of the study was to assess and quantify the state of soil structural degradation induced by agricultural operations using a suite of methods of analysis at a regional scale, with a special focus on CoreVESS. Soil core samples were taken in Belgium from 42 cropped fields, at two positions (headland and in-field zone) and from three layers, notably the ploughed topsoil (TOP, 10–20 cm), the compacted subsoil (CSUB, 30–40 cm) and the deeper subsoil (SUB, 60–70 cm), totalling the sample horizons to 252. Test and sampling sites comprised all major soil texture classes within the Belgian soil textural triangle and varied from sand to heavy clay. In-field positions (IN-FIELD) showed significantly better coreVESS-based Sq scores as compared to headland positions (HEAD), with the CSUB layers always exhibiting significantly lower quality than the other two layers. Laboratory-derived soil quality indicator (SQi) values portrayed the same trend, with CSUB layers always indicating the poorest soil quality. Significant differences in SQi's were also found between soils of acceptable (Sq ≤ 3) and degraded (Sq > 3) structure. Likewise, grouping soils into the same categories resulted in significant differences in the soil water retention and hydraulic conductivity curves in their wet ranges. There were good significant relationships between the SQi values and CoreVESS-based Sq scores, with for example Pearson R correlation coefficients of 0.64 for both penetration resistance and bulk density. Also, Sq scores related well with an SQi-based soil quality index (SQI) value averaged per layer and texture class (Pearson R of 0.60). The study confirmed that agricultural operations and their intensity clearly affect soil structural quality across various soil textures, with CoreVESS being as responsive to variation in soil structure quality as traditional quantitative methods, even when applied in the subsoil. VESS methods thus have a potential for monitoring soil structural quality over a variety of textures in a rapid, intuitive, practical and cheap way, as an alternative for or being complementary to more expensive labour-intensive traditional quantitative methods

Evolution of NIRv, VOD and soil moisture content during the summers of 2016-2018 in Raam and Twenthe, the Netherlands

Data used in the paper "Anatomy of the 2018 agricultural drought in The Netherlands using in situ soil moisture and satellite vegetation indices" in Hydrology and Earth System Sciences. Precipitation and potential evaporation are derived from KNMI stations Volkel (Raam) and Twenthe (Twenthe), where the potential evaporation is calculated using Makkink. NIRv, VOD, and soil moisture values are averaged over the regions. See paper for more details (https://doi.org/10.5194/hess-24-6021-2020)

Anatomy of the 2018 agricultural drought in the Netherlands using in situ soil moisture and satellite vegetation indices

The soil moisture status near the land surface is a key determinant of vegetation productivity. The critical soil moisture content determines the transition from an energy-limited to a water-limited evapotranspiration regime. This study quantifies the critical soil moisture content by comparison of in situ soil moisture profile measurements of the Raam and Twente networks in the Netherlands, with two satellite-derived vegetation indices (near-infrared reflectance of terrestrial vegetation, NIRv, and vegetation optical depth, VOD) during the 2018 summer drought. The critical soil moisture content is obtained through a piece-wise linear correlation of the NIRv and VOD anomalies with soil moisture on different depths of the profile. This non-linear relation reflects the observation that negative soil moisture anomalies develop weeks before the first reduction in vegetation indices: 2-3 weeks in this case. Furthermore, the inferred critical soil moisture content was found to increase with observation depth, and this relationship is shown to be linear and distinctive per area, reflecting the tendency of roots to take up water from deeper layers when drought progresses. The relations of non-stressed towards water-stressed vegetation conditions on distinct depths are derived using remote sensing, enabling the parameterization of reduced evapotranspiration and its effect on gross primary productivity in models to study the impact of a drought on the carbon cycle. </p

Anatomy of the 2018 agricultural drought in the Netherlands using in situ soil moisture and satellite vegetation indices

The soil moisture status near the land surface is a key determinant of vegetation productivity. The critical soil moisture content determines the transition from an energy-limited to a water-limited evapotranspiration regime. This study quantifies the critical soil moisture content by comparison of in situ soil moisture profile measurements of the Raam and Twente networks in the Netherlands, with two satellite-derived vegetation indices (near-infrared reflectance of terrestrial vegetation, NIRv, and vegetation optical depth, VOD) during the 2018 summer drought. The critical soil moisture content is obtained through a piece-wise linear correlation of the NIRv and VOD anomalies with soil moisture on different depths of the profile. This non-linear relation reflects the observation that negative soil moisture anomalies develop weeks before the first reduction in vegetation indices: 2–3 weeks in this case. Furthermore, the inferred critical soil moisture content was found to increase with observation depth, and this relationship is shown to be linear and distinctive per area, reflecting the tendency of roots to take up water from deeper layers when drought progresses. The relations of non-stressed towards water-stressed vegetation conditions on distinct depths are derived using remote sensing, enabling the parameterization of reduced evapotranspiration and its effect on gross primary productivity in models to study the impact of a drought on the carbon cycle

Bodemverdichting in Vlaanderen : Gevolgen van bodemverdichting op het watertransport door een bodem

De gevolgen van bodemverdichting op het watertransport door een bodem zijn verkend. Een bodemfysische database is gecreëerd door naast historische metingen nieuwe metingen te verzamelen op verdichte percelen. Dat is gebeurd door op 26 percelen op 2 plekken op 3 diepten ongestoorde monsters te nemen en de bodemfysische eigenschappen te bepalen. Op 6 percelen zijn continue hydrologische metingen verricht van bodemvocht op 3 diepten en grondwaterstanden. De laatste metingen zijn gebruikt om te toetsen of het model SWAP met de gemeten bodemfysische eigenschappen in staat is het watertransport in het perceel te beschrijven. Met SWAP zijn voor 5 Vlaamse stroomgebiedjes de effecten van bodemverdichting verkend voor klimaatscenario’s door de verdichte en niet-verdichte toestand te vergelijken. De met de pedotransferfuncties en nieuwe data berekende effecten van verdere verdichting op de waterhuishouding blijken globaal gezien beperkt te zijn. Dit neemt niet weg dat de lokale effecten mogelijk aanzienlijk kunnen zijn, gelet op de grote variatie in bodemverdichting die binnen de percelen werd opgemeten. De verschillen tussen de verdichte en niet-verdichte situatie in stroomgebieden zijn beperkt. Klimaatscenario’s leiden op verdichte bodems tot meer oppervlakkige afstroming en meer droogtegevoelighei