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See detailTwo-dimensional monitoring of soil water content in fields with plastic mulching using electrical resistivity tomography
Chen, Baoqin; Garré, Sarah ULiege; Liu, Haitao et al

in Computers and Electronics in Agriculture (2019), 159

Plastic mulching (PM) has become an important agricultural practice to improve crop yields worldwide, while there is still a lack of methods to quantify the complex spatial variations of soil water ... [more ▼]

Plastic mulching (PM) has become an important agricultural practice to improve crop yields worldwide, while there is still a lack of methods to quantify the complex spatial variations of soil water content (SWC) in the PM field. In this study, a methodology for using Electrical Resistivity Tomography (ERT) to get SWC information in the PM field was presented. Its performance in monitoring SWC was validated, and the spatial variation of SWC was analyzed using the ERT results. A simplified Waxman and Smits model was selected to calibrate the pedo-physical relationship, and it showed good performance (coefficient of determination > 0.92). With the calibrated model, the SWC obtained using ERT showed good agreement with soil moisture sensors in different soil layers (RMSE < 0.027 cm3 cm−3). The ERT results showed that rainfall and drying events have different effects on SWC at different growing stages. At the early stage, rainfall and drying events mainly influenced SWC on the bare strip, while at the later stage, rainfall and drying events had more obvious effects on the zone near the planting hole. On a seasonal scale, a higher SWC was not only found in the middle part of the mulched strip, but also in the bare strip, while a lower SWC was found in positions near the planting hole. At the same time, a high-resolution ERT measurement revealed that the SWC was also largely influenced by the soil heterogeneity. As such, SWC in the mulched strip was not necessarily higher than in the bare strip as we had supposed, but showed a high degree of irregularity in two dimensions. Considering the irregularity of SWC in two dimensions, our study calls for replacing point-scale measurement with two-dimensional monitoring methods when acquiring SWC information in a field with PM. [less ▲]

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See detailFunctional-structural root system model validation using soil MRI and tracer experiment
Koch, Axelle; Meunier, Félicien; Vanderborght, Jan et al

in Journal of Experimental Botany (2019)

Functional-structural root system models simulate the relations between root system architectural and hydraulic properties, and the spatio-temporal distributions of water and solute in the root zone. Such ... [more ▼]

Functional-structural root system models simulate the relations between root system architectural and hydraulic properties, and the spatio-temporal distributions of water and solute in the root zone. Such models might help identify optimal plant properties for breeding and contribute to increased water use efficiency. However, it must be first demonstrated that they accurately reproduce the processes they intend to describe. This is challenging because the flow and transport processes towards individual roots are hard to observe. We demonstrate how this deadlock could be broken by combining co-registered root and tracer distributions obtained from magnetic resonance imaging with a root system model in an inverse modeling scheme. The main features in the tracer distributions were well reproduced by the model using realistic root hydraulic parameters. By combining functional-structural root system model with 4D tracer observations, we were able to quantify the water uptake distribution of a growing root system. We showed that 76% of the transpiration was extracted through 3 rd order roots. The simulations also demonstrated that accurate water uptake distribution cannot be directly derived neither from observations of tracer accumulation nor from water depletion. However, detailed tracer experiments combined with process-based models help decipher mechanisms underlying root water uptake. [less ▲]

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See detailHow far can consumer grade UAV RGB imagery describe crop production? A 3D and multi-temporal modelling approach applied to Zea mays
Michez, Adrien ULiege; Bauwens, Sébastien ULiege; Brostaux, Yves ULiege et al

in Remote Sensing (2018), 10(11), 1798

In recent decades, remote sensing has increasingly been used to estimate the spatio-temporal evolution of crop biophysical parameters such as the above-ground biomass (AGB). On a local scale, the advent ... [more ▼]

In recent decades, remote sensing has increasingly been used to estimate the spatio-temporal evolution of crop biophysical parameters such as the above-ground biomass (AGB). On a local scale, the advent of unmanned aerial vehicles (UAVs) seems to be a promising trade-off between satellite/airborne and terrestrial remote sensing. This study aims to evaluate the potential of a low-cost UAV RGB solution to predict the final AGB of Zea mays. Besides evaluating the interest of 3D data and multitemporality, our study aims to answer operational questions such as when one should plan a combination of two UAV flights for AGB modeling. In this case, study, final AGB prediction model performance reached 0.55 (R-square) using only UAV information and 0.8 (R-square) when combining UAV information from a single flight with a single-field AGB measurement. The adding of UAV height information to the model improves the quality of the AGB prediction. Performing two flights provides almost systematically an improvement in AGB prediction ability in comparison to most single flights. Our study provides clear insight about how we can counter the low spectral resolution of consumer-grade RGB cameras using height information and multitemporality. Our results highlight the importance of the height information which can be derived from UAV data on one hand, and on the other hand, the lower relative importance of RGB spectral information. [less ▲]

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See detailThe ecotron as a surrogate for reality. Too good to be true? (invited talk)
Garré, Sarah ULiege; Longdoz, Bernard ULiege; Leemans, Vincent ULiege

Conference (2018, October 11)

Finding solutions to adapt to the impact of global change is still one of the most important challenges of the 21st century. While huge modelling advances have been made and experimental methods to study ... [more ▼]

Finding solutions to adapt to the impact of global change is still one of the most important challenges of the 21st century. While huge modelling advances have been made and experimental methods to study the earth system are diversifying, a major problem to find those solutions remains: the unclosed gap between spatial and temporal scales. Results from controlled experiments in pots or greenhouses are sometimes difficult to relate to observations at the field and landscape scale due to the complex interplay of various processes. In addition, it has been hard to reproduce the future effects of climate change experimentally, leading to an inevitable extrapolation of model predictions to zones where no validation is possible. Ecotrons provide unprecedented possibilities to study the soil-vegetation-microbiome-atmosphere continuum in highly controlled conditions and this under any climate scenario of interest. In this presentation, we will present the new Ecotron facility of the TERRA Research Center in Gembloux, Belgium designed to submit six mesocosms (small ecosystems) installed on lysimeters (2m² X 1,5m), to any climatic conditions desired and see how it can reproduce (or not) the current and future in-nature reality. In addition to the controlled variables, instrumentation is set up to monitor energy and water budget and ecosystem functions (yield and production quality, GHG mitigation and C storage, water retention capacity and leaching quality, soil fertility,…) In the first experiment planned, we will compare the behavior of winter wheat plots submitted to present and future climatic conditions. The present conditions will mimic the situation already recorded on the Lonzee ICOS site. The future scenario will represent a typical year of the 2050-2070 period (drift of the mean annual value and increase of the temporal variabiity) and chosen for its ability to produce a contrasting crop yield. The results will also give us information about the ability of ecotrons to reproduce a realistic ecosystem functionning and expose which aspects of plant growth and soil behavior are well and not well reproduced in the artificially generated climatic conditions. This phase is essential to demonstrate the actual potential and shortcomings of this cross-cutting research infrastructure [less ▲]

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See detailUse and challenges of electrical resistivity tomography to study processes in agro-ecosystems
Garré, Sarah ULiege; Javaux, Mathie; Manhaeghe, Thibault et al

Scientific conference (2018, September 25)

Sustainable management of agro-ecosystems requires a thorough understanding of the interaction between physical, chemical and biological processes at play. In addition, processes at pore scale are linked ... [more ▼]

Sustainable management of agro-ecosystems requires a thorough understanding of the interaction between physical, chemical and biological processes at play. In addition, processes at pore scale are linked to field scale phenomena, but this connection is often poorly understood. Electrical resistivity tomography (ERT) is increasingly used in the context of agriculture since the measured resistivity distribution can be linked to soil moisture, soil structural characteristics or pore water salinity. Due to its minimally invasive character, its spatial coverage and its monitoring abilities, ERT can be used to study field heterogeneity and competition between plants, quantify water fluxes throughout a growing season or distinguish preferential flow pathways in soils. Is resolution is well-below classical soil imaging techniques such as X-ray CT or MRI, but its spatial coverage much larger. This highlights the potential of ERT to link our knowledge obtained from pore scale data to field scale processes. Nevertheless, a lot of challenges still remain. A Tikhonov-type regularization approach is often used to solve the ill-posed, inverse problem linked to ERT, resulting in a smoothed resistivity distribution. However, in reality strong contrasts can exist due to e.g. compacted soil layers due to ploughing, water infiltration fronts, etc. and in that case other operators have been proposed to regularize the inversion. Taking into account spatial heterogeneity of petrophysical characteristics and providing a realistic uncertainty estimation are additional challenges, which can be addressed using stochastic approaches. Monitoring data provides further elements to constrain the inverse problem: data can be replaced by data difference and regularization may incorporate the temporal dimension for instance. However, such constraints require their compatibility with the studied temporal process, which is not always straightforward. Several alternative strategies are being developed, such as coupled hydrogeophysical inversion, or stochastic approaches using a prior falsification/validation method following a Popper-Bayes philosophy. In this talk, we will address some of these challenges and give some recent applications in the field of agro-geophysics. [less ▲]

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See detailEvaluation of the Effect of Micro-Topography of a Potato Field on ERT to Assess Soil Moisture Patterns in Sandy Soil
Manhaeghe, Thibault ULiege; Wagner, Florian; Dumont, Gaël ULiege et al

in Earthdoc (2018, September 09)

Electrical resistivity tomography is a method that provides a spatial-temporal characterization of the subsurface. In this project, the method is used to monitor a potato field, characterized by a ... [more ▼]

Electrical resistivity tomography is a method that provides a spatial-temporal characterization of the subsurface. In this project, the method is used to monitor a potato field, characterized by a microtopography composed of furrows and ridges. Nevertheless, changes of this micro-topography due to erosion during the growing season could lead to artefacts in the inverted resistivity distribution. To quantify this effect, we first used a hydraulic model with non-uniform infiltration patterns and converted the obtained soil moistures in bulk resistivities. We then conducted a forward modelling with a decrease of the ridge height in the mesh. Afterwards, we used the initial microtopography of the start of the growing season in the inversion and compared the retrieved resistivity distributions to the ones of the hydraulic model. We also compared different array configurations to assess which array is most suitable to retrieve the expected infiltration pattern. Gradient and Wenner configuration were performing best with a coefficient determination coefficient close to 0.9 and a RMS close to 1. The change of ridge height highly impacted the coefficient of determination once the decrease is above 6 cm. Nevertheless, pattern between furrows and ridges can still be retrieved qualitatively up until a decrease of 10 cm. [less ▲]

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See detailElectrical resistivity tomography: basic lecture (invited lecture)
Garré, Sarah ULiege

Conference (2018, August 28)

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See detailA new method for characterizing the complex electrical properties of root segments
Ehosioke, Solomon ULiege; Garré, Sarah ULiege; Kremer, Thomas ULiege et al

Conference (2018, July 09)

The application of geophysical methods to root investigation is increasing in recent years because of the limitations associated with the use of traditional methods (root excavation, monoliths ... [more ▼]

The application of geophysical methods to root investigation is increasing in recent years because of the limitations associated with the use of traditional methods (root excavation, monoliths, minirhizotron etc.). Point sampling is only partially satisfactory as a result of the spatial variability and dynamics of the roots zone. Geophysical methods address these limitations by offering high resolution and non-invasive approaches to root investigation due to their ability to infer properties and structures of the subsurface as well as the flow and transport processes occurring in the shallow subsurface, at various spatial scales. Recent studies (Weigand and Kemna 2017; Mary et al. 2017) have reported a low frequency polarization of root systems and have shown that SIP/EIT holds a promising future for root system characterization. Despite these significant improvements, there is still a knowledge gap regarding the electrical response of fine roots at the segment scale which is essential to enable us to account for the effect of roots in the estimation of soil moisture content of rooted soils or to exploit electromagnetic methods to characterize certain root system characteristics. We hereby propose a method for the characterization of electrical properties of single root segments of various plants resulting from an externally applied electrical field. A sample holder was designed and tested on ideal resistors and root segments, and was found to be suitable for assessing the electrical properties of root segments of 1-5 cm length and 2 mm diameter at a frequency range of 1Hz – 45 KHz. The system was then used to obtain complex electrical responses of the root segments of the target plants in the laboratory. This enabled us to study different root properties and their effects on the root electrical signals. Our results suggest that fine roots could be differentiated from soils because they show lower resistivity and polarizes more than soils. [less ▲]

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See detailImpact of crop residue management on crop production and soil chemistry after seven years of crop rotation in temperate climate, loamy soils
Hiel, Marie-Pierre ULiege; Barbieux, Sophie; Pierreux, Jérome ULiege et al

in PeerJ (2018), 6(e4836),

Society is increasingly demanding a more sustainable management of agro-ecosystems in a context of climate change and an ever growing global population. The fate of crop residues is one of the important ... [more ▼]

Society is increasingly demanding a more sustainable management of agro-ecosystems in a context of climate change and an ever growing global population. The fate of crop residues is one of the important management aspects under debate, since it represents an unneglectable quantity of organic matter which can be kept in or removed from the agro-ecosystem. The topic of residue management is not new, but the need for global conclusion on the impact of crop residue management on the agro-ecosystem linked to local pedo-climatic conditions has become apparent with an increasing amount of studies showing a diversity of conclusions. This study specifically focusses on temperate climate and loamy soil using a seven-year data set. Between 2008 and 2016, we compared four contrasting residue management strategies differing in the amount of crop residues returned to the soil (incorporation vs. exportation of residues) and in the type of tillage (reduced tillage (10 cm depth) vs. conventional tillage (ploughing at 25 cm depth)) in a field experiment. We assessed the impact of the crop residue management on crop production (three crops—winter wheat, faba bean and maize—cultivated over six cropping seasons), soil organic carbon content, nitrate (NO−3), phosphorus (P) and potassium (K) soil content and uptake by the crops. The main differences came primarily from the tillage practice and less from the restitution or removal of residues. All years and crops combined, conventional tillage resulted in a yield advantage of 3.4% as compared to reduced tillage, which can be partly explained by a lower germination rate observed under reduced tillage, especially during drier years. On average, only small differences were observed for total organic carbon (TOC) content of the soil, but reduced tillage resulted in a very clear stratification of TOC and also of P and K content as compared to conventional tillage. We observed no effect of residue management on the NO−3 content, since the effect of fertilization dominated the effect of residue management. To confirm the results and enhance early tendencies, we believe that the experiment should be followed up in the future to observe whether more consistent changes in the whole agro-ecosystem functioning are present on the long term when managing residues with contrasted strategies. [less ▲]

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See detailCalibration of soil moisture sensors for a long-term field experiment
D'ortona, Lolita; Duhamel, Jimmy; François, Yohann et al

Poster (2018, April 10)

In the framework of the ICOS RI network, a field site in Lonzée, Belgium, is equipped to provide long-term data on greenhouse gas emissions from an agricultural field and the associated environmental ... [more ▼]

In the framework of the ICOS RI network, a field site in Lonzée, Belgium, is equipped to provide long-term data on greenhouse gas emissions from an agricultural field and the associated environmental variables. Soil moisture is one of the state variables which are monitored with high temporal resolution and with several repetitions in the field to take into account soil heterogeneity. In order to facilitate field installation in combination with agricultural practices, Sentek Enviroscan sensors, a collection of FDR sensors at different depths on a stick, were chosen to measure soil moisture. In this contribution, we will discuss the results of a detailed calibration experiment we performed for this sensor type and compare it to the results we got from a different FDR sensor: the ML3 Thetaprobe. We calibrated the probes for the different soil horizons at 3 different locations in the field using big reconstructed soil columns which were brought to defined soil moisture levels in the lab. The results showed that the universal calibration relationship of the sensors gave quite similar results as the soil-specific calibration up till a moisture content of 40%. We also observed that the higher the soil moisture content becomes, the more difficult it is to obtain a homogeneous distribution of the water in the calibration column which might have an impact on the sensor readings. [less ▲]

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See detailUse and challenges of geophysics to study processes in agro-ecosystems (invited)
Garré, Sarah ULiege; Javaux, Mathieu; Dumont, Gaël ULiege et al

Conference (2018, April 05)

Electrical resistivity tomography (ERT) is increasingly used in the context of agriculture since the measured resistivity distribution can be linked to soil moisture, soil structure or pore water salinity ... [more ▼]

Electrical resistivity tomography (ERT) is increasingly used in the context of agriculture since the measured resistivity distribution can be linked to soil moisture, soil structure or pore water salinity. Due to its minimally invasive character, its spatial coverage and its monitoring abilities, ERT can be used to study field heterogeneity and competition between plants, quantify water fluxes throughout a growing season or distinguish preferential flow pathways in soils. Nevertheless, a lot of challenges still remain. From a mathematical point of view, the inverse problem linked to ERT is ill-posed. To solve it, the inverse problem is often regularized with a Tikhonov-type approach resulting in a smoothed resistivity distribution. However, in reality strong contrasts can exist due to e.g. compacted soil layers due to ploughing, water infiltration fronts, etc. and in that case other operators have been proposed to regularize the inversion. Taking into account spatial heterogeneity of petrophysical characteristics and providing a realistic uncertainty estimation are additional challenges, which can be addressed using stochastic approaches. Monitoring data provides further elements to constrain the inverse problem: data can be replaced by data difference and regularization may incorporate the temporal dimension for instance. However, such constraints require their compatibility with the studied temporal process, which is not always straightforward. Several alternative strategies are being developed, such as coupled hydrogeophysical inversion, or stochastic approaches using a prior falsification/validation method following a Popper-Bayes philosophy. In this presentation, we will illustrate the mentioned challenges and some recent developments in the context of agrogeophysics. [less ▲]

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See detailEen bril maken waarmee je in de grond kan kijken?
Garré, Sarah ULiege

Conference given outside the academic context (2018)

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See detailModelling soil water dynamic in rain-fed spring maize field with plastic mulching
Chen, Baoqing ULiege; Liu, Enke; Mei, Xurong et al

in Agricultural Water Management (2018)

Numerical solution of the Richards equation with Hydrus-2D model is a low cost and fast way to get information on spatio-temporal soil water dynamics. Previous researches with Hydrus-2D have developed two ... [more ▼]

Numerical solution of the Richards equation with Hydrus-2D model is a low cost and fast way to get information on spatio-temporal soil water dynamics. Previous researches with Hydrus-2D have developed two different approaches to represent the rainfall infiltration in irrigated field with plastic mulching: ‘BP’ – an approach comprised by bare strip boundary and plastic strip boundary without consideration of film side infiltration;‘BP + ’- an approach comprised by bare strip and plastic strip with integrating the process of film side infiltration by increasing the rainfall infiltration amount in bare strip. Nevertheless, the performance of these approaches has not yet been evaluated in rain-fed fields. Considering much more dominant role of rainfall infiltration in rain-fed agriculture, we tested an additional approach which comprised a bare strip, plastic strip and planting hole (BPH) to take into account the effect of the rainfall canopy redistribution and film side infiltration, and we compared its performance to the two existing approaches. Results suggested BP completely failed to reproduce the soil water content (SWC) in all soil layers of plastic strip and in the deep soil layers of bare strip. BP+ overestimated the SWC in 0–20 cm of the bare strip, while the performance of BPH was acceptable in different positions. After that, we compared the soil water distribution between no-mulched field (NM) and plastic mulched field (PM) with approach BPH. Our simulation showed that the highest SWC in PM occurred near the planting hole,SWC in the center zone of plastic strip was lower, while SWC in the bare strip was lowest. PM improves the soil water availability not only in the plastic strip but also in the bare strip as compared to NM [less ▲]

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See detailNoninvasive imaging of processes in natural porous media: From pore to field scale
Pohlmeier, Andreas; Garré, Sarah ULiege; Roose, Tiina

in Vadose Zone Journal (2018), 17(1),

Noninvasive, high-resolution imaging techniques are important for visualizing water flow and transport processes in soils, which are natural porous media. They are a key to understanding effects such as ... [more ▼]

Noninvasive, high-resolution imaging techniques are important for visualizing water flow and transport processes in soils, which are natural porous media. They are a key to understanding effects such as crop production, water resource restoration, CO2 sequestration, or the transport and fate of pollutants. During the last two decades, the development of three-dimensional imaging techniques such as nuclear magnetic resonance imaging (NMR and MRI), X-ray computed tomography (CT), and neutron CT has made significant progress possible in the study of soil processes. This special section presents examples of X-ray CT and NMR from the small-column scale to the application of portable NMR equipment in the field, along with some important advances in image processing that make it possible to extract optimal physical information from the original data. [less ▲]

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See detailHow does STICS crop model simulate crop growth and productivity under shade conditions?
Artru, Sidonie ULiege; Dumont, Benjamin ULiege; Ruget, Francois et al

in Field Crops Research (2018), 215

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See detailChapter Ground-based soil moisture determination. In: Ecohydrology. Observation and Measurement of Ecohydrological Processes
Jonard, François; Bogena, Heye; Caterina, David et al

Book published by Springer (2018)

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See detailA tree-bordered field as a surrogate for agroforestry in temperate regions: Where does the water go?
Coussement, Tom; Maloteau, Sophie; Pardon, Paul et al

in Agricultural Water Management (2018), 210

There is a renewed interest in temperate agroforestry systems because of their potential to increase biodiversity, sequester carbon and diversify the landscape while maintaining productivity. Little ... [more ▼]

There is a renewed interest in temperate agroforestry systems because of their potential to increase biodiversity, sequester carbon and diversify the landscape while maintaining productivity. Little quantitative information is available about the interaction between trees and the crop for water, especially in temperate climate and for tree ages towards the end of an agroforestry cycle. With this study, we quantified the effect of mature poplar trees on soil moisture dynamics in space and time in an agricultural field sown with maize during one growing season. We confirmed the ability of electrical resistivity tomography to study tree-crop interactions for water under field conditions and we delimited an area of influence of the 40-year old trees on the crop of about 15 m. In order to do this, we installed four 30 m electrode transects perpendicular to the field border. Three transects were located next to a tree-bordered part of the field and one reference transect was located along the same border, but without any tree present. We performed seven electrical resistivity tomography (ERT) measurements during the maize growing season and compared the soil moisture distribution and dynamics with and without tree border as a proxy for a mature agroforestry system. We showed that the ERT tomograms in a tree-bordered zone are significantly different from a reference zone without trees along the 30 m of the transect using a single and segmented linear regression analysis. This article shows the potential of ERT to quantify tree-crop-soil interactions for water in agroforestry systems. [less ▲]

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See detailImpact of climate change on potential evapotranspiration under a historical and future climate scenario in the Huang-Huai-Hai Plain, China
Liu, Qin; Yan, Changrong; Ju, Hui et al

in Theoretical and Applied Climatology (2018)

Climate change is widely accepted to be one of the most critical problems faced by the Huang-Huai-Hai Plain (3H Plain), which is a region in which there is an over-exploitation of groundwater region and ... [more ▼]

Climate change is widely accepted to be one of the most critical problems faced by the Huang-Huai-Hai Plain (3H Plain), which is a region in which there is an over-exploitation of groundwater region and where future warmer and drought conditions might intensify crop water demand. In this study, the spatiotemporal patterns of ET0 and primary driving meteorological variables were investigated based on a historical and RCP 8.5 scenario daily data set from 40 weather stations over the 3H Plain using linear regression, spline interpolation method, a partial derivative analysis and multivariate regression. The results indicated a negative trend in all the analysis periods (except spring) of the past 54 years of which only summer and the entire year were statistically significant (p < 0.01) with slopes of -1.09 and -1.30 mm·a-1 respectively. In contrast, a positive trend was observed in all four seasons and the entire year under the RCP 8.5 scenario, with the biggest increment equal to 1.36 mm·a-1 in summer and an annual increment of 3.37 mm·a-1. The spatial patterns of the seasonal and annual ET0 exhibited the lowest values in southeastern regions and the highest values in northeastern parts of Shandong Province, probably because of the combined effects of various meteorological variables over the past 54 years. Relative humidity (RH) together with solar radiation (RS) were detected to be the main climatic factors controlling the reduction of ET0 in summer, autumn, and the entire year on the 3H Plain. ET0 in spring was mainly sensitive to changes in RS and RH, whereas ET0 in winter was most sensitive to changes in wind speed (WS) and decreased due to declining RH. Under the future RCP 8.5 scenario, the annual ET0 distribution displays a rich spatial structure with a clear northeast-west gradient and anarea with low values in the southern regions, which is similarly detected in spring and summer. The most sensitive and primary controlling variables with respect to the increment of future ET0 are in the first place RS and then mean temperature in spring, while turn to be mean temperature and then RS in summer. In autumn, future ET0 is most sensitive to RH changes. WS and RH are the controlling variables for ET0 in winter. Annual future ET0 is most sensitive to RH changes and accordingly RS is responsible for the predicted increment of the annual ET0. Better understanding of current and future spatiotemporal patterns of ET0 and of the regional response of ET0 to climate change can contribute to the establishment of a policy to realize a more efficient use of water resources and a sustainable agricultural production in the 3H Plain. [less ▲]

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See detailGreen roofs as a primer for urban biodiversity?
Bernard, Cedric; Garré, Sarah ULiege; Mahy, Grégory ULiege et al

Scientific conference (2018)

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See detailModelling soil water dynamic in rain-fed spring maize field with plastic mulching
Chen, Baoqing ULiege; Liu, Enke; Mei, Xurong et al

in Agricultural Water Management (2018)

Numerical solution of the Richards equation with Hydrus-2D model is a low cost and fast way to get information on spatio-temporal soil water dynamics. Previous researches with Hydrus-2D have developed two ... [more ▼]

Numerical solution of the Richards equation with Hydrus-2D model is a low cost and fast way to get information on spatio-temporal soil water dynamics. Previous researches with Hydrus-2D have developed two different approaches to represent the rainfall infiltration in irrigated field with plastic mulching: ‘BP’ – an approach comprised by bare strip boundary and plastic strip boundary without consideration of film side infiltration;‘BP + ’- an approach comprised by bare strip and plastic strip with integrating the process of film side infiltration by increasing the rainfall infiltration amount in bare strip. Nevertheless, the performance of these approaches has not yet been evaluated in rain-fed fields. Considering much more dominant role of rainfall infiltration in rain-fed agriculture, we tested an additional approach which comprised a bare strip, plastic strip and planting hole (BPH) to take into account the effect of the rainfall canopy redistribution and film side infiltration, and we compared its performance to the two existing approaches. Results suggested BP completely failed to reproduce the soil water content (SWC) in all soil layers of plastic strip and in the deep soil layers of bare strip. BP+ overestimated the SWC in 0–20 cm of the bare strip, while the performance of BPH was acceptable in different positions. After that, we compared the soil water distribution between no-mulched field (NM) and plastic mulched field (PM) with approach BPH. Our simulation showed that the highest SWC in PM occurred near the planting hole, SWC in the center zone of plastic strip was lower, while SWC in the bare strip was lowest. PM improves the soil water availability not only in the plastic strip but also in the bare strip as compared to NM. [less ▲]

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