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See detailOutcomes from the MACSUR grassland model inter-comparison with the model CARAIB
Minet, Julien ULg; Laloy, Eric; Tychon, Bernard ULg et al

Conference (2014, October 15)

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See detailAquaCrop: Manuel d'utilisation
Raes, Dirk; Steduto, Paquale; Hsiao, Theodore et al

Learning material (2014)

Le logiciel AquaCrop est un modèle de bilan d’eau qui permet d’évaluer les efficiences en irrigation, l’élaboration des calendriers d’irrigation au niveau de la parcelle et l'estimation des rendements ... [more ▼]

Le logiciel AquaCrop est un modèle de bilan d’eau qui permet d’évaluer les efficiences en irrigation, l’élaboration des calendriers d’irrigation au niveau de la parcelle et l'estimation des rendements. AquaCrop a été sélectionné en raison de sa simplicité et de sa robustesse, et du nombre limité de variables à introduire. Il existe bien des modèles déterministes, mais pour fonctionner correctement, ils exigent des paramètres d’entrée très détaillés qui ne sont pas toujours disponibles quand il s’agit de recherche en milieu rural (‘on-farm’). [less ▲]

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See detailBrown rust disease control in winter wheat: II. Exploring the optimization of fungicide sprays through a decision support system
El Jarroudi, Moussa ULg; kOUADIO, Louis; Giraud, Frédéric et al

in Environmental Science & Pollution Research (2014), 21(4), 4809-4818

A decision support system (DSS) involving an approach for predicting wheat leaf rust (WLR) infection and progress based on night weather variables (i.e., air temperature, relative humidity, and rainfall ... [more ▼]

A decision support system (DSS) involving an approach for predicting wheat leaf rust (WLR) infection and progress based on night weather variables (i.e., air temperature, relative humidity, and rainfall) and a mechanistic model for leaf emergence and development simulation (i.e., PROCULTURE) was tested in order to schedule fungicide time spray for controlling leaf rust progress in wheat fields. Experiments including a single fungicide treatment based upon the DSS along with double and triple treatment were carried out over the 2007–2009 cropping seasons in four representative Luxembourgish wheat field locations. The study showed that the WLR occurrences and severities differed according to the site, cultivar, and year. We also found out that the single fungicide treatment based on the DSS allowed a good protection of the three upper leaves of susceptible cultivars in fields with predominant WLR occurrences. The harvested grain yield was not significantly different from that of the double and triple fungicide-treated plots (P < 0.05). Such results could serve as basis or be coupled to cost-effective and environmentally friendly crop management systems in operational context. [less ▲]

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See detailBayesian inference of a dynamic vegetation model for grassland
Minet, Julien ULg; Laloy, Eric; Tychon, Bernard ULg et al

Conference (2014, April 02)

As a part of the MACSUR task L2.4, we probabilistically calibrated the CARAIB dynamic vegetation model by Markov chain Monte Carlo (MCMC) simulation with the DREAMZS sampler.. CARAIB is a mechanistic ... [more ▼]

As a part of the MACSUR task L2.4, we probabilistically calibrated the CARAIB dynamic vegetation model by Markov chain Monte Carlo (MCMC) simulation with the DREAMZS sampler.. CARAIB is a mechanistic model that calculates the carbon assimilation of the vegetation as a function of the soil and climatic conditions, and can thus be used for simulating grassland production under cutting or grazing management. Bayesian model inversion was performed at 4 grassland sites across Europe: Oensingen, CH; Grillenburg, DE; Laqueuille, FR and Monte-Bodone, IT. Four daily measured variables from these sites: the Gross Primary Productivity (GPP), Net Ecosystem Exchange (NEE), Evapotranspiration (ET) and Soil Water Content (SWC) were used to sample 10 parameters related to rooting depth, stomatal conductance, specific leaf area, carbon-nitrogen ratio and water stresses. The maximized likelihood function therefore involved four objectives, whereas the applied Bayesian framework allowed for assessing the so called parameter posterior probability density function (pdf), which quantifies model parameter uncertainty caused by measurement and model errors. Sampling trials were performed using merged data from all sites (all-sites-sampling) and for each site (site-specific sampling) separately. The derived posterior parameter pdfs from the all-sites sampling and site-specific sampling runs showed differences in relation with the specificities of each site. Analysis of these distributions also revealed model sensitivity to parameters conditioned on the measured data, as well as parameter correlations. [less ▲]

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See detailSoil organic carbon assessment by field and airborne spectrometry in bare croplands: accounting for soil surface roughness
Denis, Antoine ULg; Stevens, Antoine; Van Wesemael, Bas et al

in Geoderma (2014), 226-227(August 2014), 94102

Visible, Near and Short Wave Infrared (VNSWIR) diffuse reflectance spectroscopy (350 nm to 2500 nm) has been proven to be an efficient tool to determine the Soil Organic Carbon (SOC) content. SOC ... [more ▼]

Visible, Near and Short Wave Infrared (VNSWIR) diffuse reflectance spectroscopy (350 nm to 2500 nm) has been proven to be an efficient tool to determine the Soil Organic Carbon (SOC) content. SOC assessment (SOCa) is usually done by using calibration samples and multivariate models. However one of the major constraints of this technique, when used in field conditions is the spatial variation in surface soil properties (soil water content, roughness, vegetation residue) which induces a spectral variability not directly related to SOC and hence reduces the SOCa accuracy. This study focuses on the impact of soil roughness on SOCa by outdoor VIS-NIR-SWIR spectroscopy and is based on the assumption that soil roughness effect can be approximated by its related shadowing effect. A new method for identifying and correcting the effect of soil shadow on reflectance spectra measured with an Analytical Spectral Devices (ASD) spectroradiometer and an Airborne Hyperspectral Sensor (AHS-160) on freshly tilled fields in the Grand Duchy of Luxembourg was elaborated and tested. This method is based on the shooting of soil vertical photographs in the visible spectrum and the derivation of a shadow correction factor resulting from the comparison of “reflectance” of shadowed and illuminated soil areas. Moreover, the study of laboratory ASD reflectance of shadowed soil samples showed that the influence of shadow on reflectance varies according to wavelength. Consequently a correction factor in the entire [350–2500 nm] spectral range was computed to translate this differential influence. Our results showed that SOCa was improved by 27% for field spectral data and by 25% for airborne spectral data by correcting the effect of soil relative shadow. However, compared to simple mathematical treatment of the spectra (first derivative, etc.) able to remove variation in soil albedo due to roughness, the proposed method, leads only to slightly more accurate SOCa. [less ▲]

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See detailCan a global dynamic vegetation model be used for both grassland and crop modeling at the local scale?
Minet, Julien ULg; Tychon, Bernard ULg; Jacquemin, Ingrid ULg et al

Poster (2014, February)

We report on the use of a dynamic vegetation model, CARAIB, within two modeling exercises in the framework of MACSUR. CARAIB is a physically-based, mechanistic model that calculates the carbon ... [more ▼]

We report on the use of a dynamic vegetation model, CARAIB, within two modeling exercises in the framework of MACSUR. CARAIB is a physically-based, mechanistic model that calculates the carbon assimilation of the vegetation as a function of the soil and climatic conditions. Within MACSUR, it was used in the model intercomparison exercises for grassland and crop modeling, in the LiveM 2.4 and CropM WP4 tasks, respectively. For grassland modeling, blind model runs at 11 locations were performed for various time ranges (few years). For crop modeling, a sensitivity analysis for building impact response surfaces (IRS) was performed, based on a bench of model runs at different levels of perturbation in the temperature and precipitation input data over 30 years. For grassland modeling, specific management functions accounting for the cutting or grazing of the grass were added to the model, in the framework of the MACSUR intercomparison. Initially developed for modeling the carbon dynamics of the natural vegetation, CARAIB was already adapted for crop modeling but further modifications regarding the management, i.e., yearly-dependent sowing dates, were introduced. For grassland modeling, simulation results will be further intercompared with other modeling groups, but preliminary results showed that the model could cope with the introduction of the grass cutting module. For crop modeling, building the IRS over 30 years permitted to assess the sensitivity of the model to temperature and precipitation changes. So far, the participation of CARAIB in the intercomparison exercises within MACSUR resulted in further improvements of the model by introducing new functionalities. [less ▲]

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See detailImplementing agricultural land-use in the CARAIB dynamic vegetation model
François, Louis ULg; Jacquemin, Ingrid ULg; Fontaine, Corentin et al

Conference (2014)

CARAIB (Dury et al., iForest - Biogeosciences and Forestry, 4:82-99, 2011) is a state-of-the-art dynamic vegetation model with various modules dealing with (i) soil hydrology, (ii) photosynthesis/stomatal ... [more ▼]

CARAIB (Dury et al., iForest - Biogeosciences and Forestry, 4:82-99, 2011) is a state-of-the-art dynamic vegetation model with various modules dealing with (i) soil hydrology, (ii) photosynthesis/stomatal regulation, (iii) carbon allocation and biomass growth, (iv) litter/soil carbon dynamics, (v) vegetation cover dynamics, (vi) seed dispersal, and (vii) vegetation fires. Climate and atmospheric CO2 are the primary inputs. The model calculates all major water and CO2/carbon fluxes and pools. It can be run with plant functional types or species (up to 100 different species) at various spatial scales, from the municipality to country or continental levels. Within the VOTES project (Fontaine et al., Journal of Land Use Science, 2013, DOI:10.1080/1747423X.2013.786150), the model has been improved to include crops and meadows, and some modules have been written to translate model outputs into quantitative indicators of ecosystem services (e.g., evaluate crop yield from net primary productivity or calculate soil erosion from runoff, slope, grown species and various soil attributes). The model was run over an area covering four municipalities in central Belgium, where land-use is dominated by crops, meadows, housing and some forests and was introduced in the model at the land parcel level. Simulations were also performed for the future. In these simulations, CARAIB was combined with the Aporia Agent-Based Model, to project land-use changes up to 2050. This approach is currently extended within the MASC project (funded by Belgian Science Policy, BELSPO) to the whole Belgian territory (at 1 km2) and to Western Europe (at 20 km x 20 km). [less ▲]

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See detailThe Agrometeorological crop yield forecasting System of Armenia - User Manual - December 2013
Tychon, Bernard ULg; Denis, Antoine ULg; Djaby, Bakary ULg et al

Learning material (2013)

« This document was produced under the Agrometeorological component of the “EC/FAO Programme on Information Systems to Improve Food Security Decision-Making in ENP East Area” in Armenia. The objective of ... [more ▼]

« This document was produced under the Agrometeorological component of the “EC/FAO Programme on Information Systems to Improve Food Security Decision-Making in ENP East Area” in Armenia. The objective of the Programme in Armenia is to support government’s priorities to reduce food insecurity and poverty by improving the quality and sharing of information across institutions, and promoting evidence-based analyses and assessments. This User Manual of Crop Yield Forecasting System used in Armenia may be used as a reference document for the future calculation of yield forecasts that HYDROMET will use in the coming years. [less ▲]

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See detailInitiation à ENVI
Midekor, Akoly; Wellens, Joost ULg; Tychon, Bernard ULg

Learning material (2013)

Ce cours présente les concepts de base de la télédétection ainsi que certaines techniques de traitement et de classification d’images satellitaires à l’aide du logiciel ENVI. On commence par se ... [more ▼]

Ce cours présente les concepts de base de la télédétection ainsi que certaines techniques de traitement et de classification d’images satellitaires à l’aide du logiciel ENVI. On commence par se familiariser avec d’images satellites en les étudiant dans les modules ENVI Zoom et ENVI. Le cours se focalise après sur les différentes techniques de classification les plus utilisées : classification non-supervisée, supervisée ou par arbre de décision, et une analyse pratique de changement temporel de l’occupation de sol à partir d’images satellites. Les données de base de ces exercices sont tirées de la base de données du projet GEeau et traitent les différentes problématiques de gestion de l’eau et de l’environnement dans l’Ouest du Burkina Faso. [less ▲]

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See detailPerformance assessment of the FAO AquaCrop model for irrigated cabbage on farmer plots in a semi-arid environment
Wellens, Joost ULg; Raes, Dirk; Traore, Farid et al

in Agricultural Water Management (2013), 127

Small-scale irrigation initiatives are expanding rapidly in Burkina Faso. However, in many cases optimal yields are not being obtained despite the available water and the required nutrient applications ... [more ▼]

Small-scale irrigation initiatives are expanding rapidly in Burkina Faso. However, in many cases optimal yields are not being obtained despite the available water and the required nutrient applications. Local stakeholders need an easy-to-use decision-support tool to assess irrigation water use and its impact on yield. In this study, a water-driven crop model, AquaCrop, developed by FAO, was adapted for cabbage (Brassica oleracea L.) using a limited dataset and leave-one-out cross-validation (LOOCV). The experiment was conducted in south-western Burkina Faso on small irrigated farmer plots, where optimal managerial conditions could not always be guaranteed. Statistical indicators – normalized root mean square error (nRMSE) and index of agreement (d) – suggested that the model is very reliable for simulating cabbage biomass yield and soil water content (low nRMSE and d-index near 1). The relationship between observed and simulated yield produced a d-index of 0.99 and an nRMSE of 1.39% (or 0.59 ton/ha). The comparison between observed and modeled soil water content gave a d-index of 0.90 and an nRMSE of 4.38% (or 9.13 mm). Also of interest was the indirect link between plant density and yield via maximum canopy cover, which can considerably simplify yield estimation. It was concluded that AquaCrop was a very useful tool for enabling local end-users to evaluate and optimize cabbage yield and irrigation water use. [less ▲]

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See detailProfitability of using warning system for foliar disease of wheat in the Grand-Duchy of Luxembourg.
El Jarroudi, Moussa ULg; Kouadio, Louis; Beyer, Marco et al

Poster (2013, August 10)

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See detailAn easy and low-cost method for preprocessing and matching small-scale amateur aerial photography for assessing agricultural land use in Burkina Faso
Wellens, Joost ULg; Midekor, Akoly; Traore, Farid ULg et al

in International Journal of Applied Earth Observation and Geoinformation (2013), 23

In recent decades, the Kou watershed in south-western Burkina Faso has suffered from poor water management. Despite the abundance of water, most water users regularly face water shortages because of the ... [more ▼]

In recent decades, the Kou watershed in south-western Burkina Faso has suffered from poor water management. Despite the abundance of water, most water users regularly face water shortages because of the increase in the amount of land under irrigation. To help them achieve a more equitable allocation of irrigated land, local stakeholders need an easily managed low-cost tool for monitoring and mapping these irrigated zones. The aim of this study was to develop a fast and low-cost procedure for mosaicing and georeferencing amateur small-scale aerial photographs for land-use surveys. Sets of tens (2009) and hundreds (2007) of low-altitude aerial photographs, with a resolution of 0.4 m and 0.8 m, respectively, were used to create a detailed land-cover map of typical African small-scale irrigated agriculture. A commercially available stitching tool and GIS allowed georeferenced ‘mono-images’ to be constructed; both mosaics were warped on a high-resolution SPOT image with a horizontal root mean square error (RMSE) of about 11 m. The RMSE between the two image datasets was 2 m. This approach is less sensitive to atmospheric conditions that are non-predictable in programming satellite imagery. [less ▲]

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See detailFactors affecting Tan Spot on winter wheat in the Grand-Duchy of Luxembourg
El Jarroudi, Moussa ULg; Kouadio, Louis; Beyer, Marco et al

in Journal of Plant Pathology [=JPP] (2013), s1

Tan spot caused by Drechslera tritici-repentis was identified for the first time in the Grand-Duchy of Luxembourg (GDL) in 1999 on the basis of morphological characters. In order to optimize disease ... [more ▼]

Tan spot caused by Drechslera tritici-repentis was identified for the first time in the Grand-Duchy of Luxembourg (GDL) in 1999 on the basis of morphological characters. In order to optimize disease control measures in this country, tillage methods, cultivar resistance, and fungicides effects were investigated during 1999-2009 in four sites. Over this period, only three years (i.e. 1999, 2000, and 2009) with epidemic outbreak were recorded. Field experiments showed a significant difference in disease severity between sites (P < 0.001), cultivars (P < 0.0001) and years (P < 0.001). In years with epidemic outbreak, the interaction of cultivars with non-inversion tillage, intensive winter wheat production, and favorable weather conditions caused an early outbreak of the disease and a significant severity at growth stage 83 (early dough). Non-inversion tillage was found to be a major factor increasing the tan spot severity compared to conventional tillage. Furthermore, the analysis revealed that the disease severity was related to the cultivar’s susceptibility. For cultivars with similar phenology, the severity differed between the cultivar with the highest and the one with ne lowest susceptibility by a factor of two to four. The study also showed that no fungicide (mix of triazoles and strobilurins) effect was observed in the epidemic years, except in 2000. [less ▲]

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See detailSpatial Distribution of Calibrated WOFOST Parameters and Their Influence on the Performances of a Regional Yield Forecasting System
Djaby, Bakary ULg; Louis, Kouadio; El Jarroudi, Moussa ULg et al

in Sustainable Agriculture Research (2013)

We investigate in this study (i) a redefinition of crop variety zonations at a spatial scale of 10x10 km, and (ii) the influence of recalibrated crop parameters on regional yield forecasting of winter ... [more ▼]

We investigate in this study (i) a redefinition of crop variety zonations at a spatial scale of 10x10 km, and (ii) the influence of recalibrated crop parameters on regional yield forecasting of winter wheat and grain maize in western Europe. The baseline zonation and initial crop parameter set was derived from the operational European crop growth monitoring system (CGMS) which involves the agrometeorological model WOFOST. Air temperature data from 325 weather stations over the 1992-2007 period were used to define new zonations in a 300 x 300 km test site. Two parameters which influenced mostly the phenological development stages (i.e. TSUM1 and TSUM2, the effective air temperature sums from emergence to anthesis, and from anthesis to maturity, respectively) were chosen and calibrated. The CGMS was finally run based on these new recalibrated parameters and simulated crop status indicators were compared with official statistics over the 2000-2007 period. Our results showed that the days of anthesis and maturity were simulated with coefficients of determination (R2) ranging from 0.22 to 0.87 for both crops over the study site. A qualitative assessment of maximum leaf area index and harvest index also revealed a more consistent spatial pattern than the initial zonation in the simulation results. Finally, recalibrated TSUM1 and TSUM2 led to improved relationships between official yield and simulated crop indicators (significant R2 in 17 out of 28 and in 14 out of 59 NUTS3 regions with respect to the best predictor for grain maize and winter wheat, respectively). [less ▲]

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See detailProfitability of using warning system for foliar disease of wheat in the Grand-Duchy of Luxembourg
El Jarroudi, Moussa ULg; Kouadio, Louis; Beyer, Marco et al

in Phytopathology (2013), 103

Although small grain cereals (i.e. winter wheat) are routinely protected with two or three foliar treatments in the Grand-Duchy of Luxembourg (GDL), environmental concerns and changes in the cost-benefit ... [more ▼]

Although small grain cereals (i.e. winter wheat) are routinely protected with two or three foliar treatments in the Grand-Duchy of Luxembourg (GDL), environmental concerns and changes in the cost-benefit ratio are likely to increase the demand for more accurate identification of spraying needs. A Vol. 103 (Supplement 2), No. 6, 2013 S2.39 warning system assessing in real time the risk of progression of fungal diseases on winter wheat (Triticum aestivum L.) was tested in the GDL over the 2009-2012 period in four-replicated field experiments located in three representative villages of the different agro-climatological zones. The fungicide treatments recommended by the warning system during this period have ensured economic profitability equivalent to or even better than double and triple treatments. In 2010 and 2011, weather conditions impeded fungal infections of wheat and no warning was issued, reducing fungicide use. The study also highlighted that multiple fungicide applications were not better than a single application. In 2009 and 2012, although the weather conditions were very favourable for fungal wheat diseases, the single recommended fungicide application resulted in an additional yield of 30% compared to untreated plots. This study shows the importance of the positioning of fungicide treatment in such a warning system and in strategies aiming at reducing the spread fungicide molecules in the environment. [less ▲]

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See detailOperational warning for Septoria leaf blotch and leaf rust in winter wheat: Importance of fungicide dosage, formulation, and spray time
El Jarroudi, Moussa ULg; Kouadio, Louis; Beyer, Marco et al

in Phytopathology (2013), 103

Field experiments were conducted in 2010 to investigate the effect of fungicide commercial formulation, timing and dosages on the severity of these two diseases in winter wheat in Luxembourg. Different ... [more ▼]

Field experiments were conducted in 2010 to investigate the effect of fungicide commercial formulation, timing and dosages on the severity of these two diseases in winter wheat in Luxembourg. Different types of fungicides and fungicide combinations containing active ingredients such as triazoles and strobilurins were used in field trials including susceptible cultivars to Septoria leaf blotch (SLB, caused by Septoria tritici) and wheat leaf rust (WLR, caused by Puccinia triticina). The three formulations of fungicides tested were: (i) a mix of triazole and amine (Prothioconazole 250 g/l + Spiroxamine 500 g/l) associated with chlorothalonil 500 g/l, (ii) sole strobilurin (Azoxystrobine 250 g/l), and (iii) a mix of strobilurin and triazole (Epoxiconazole 125 g/l; Azoxystrobine 250 g/l). The optimum time of fungicide spray was assessed through the mechanistic model PROCULTURE and a stochastic model based on night favourable weather conditions conducive to WLR development. The results showed that for plots treated with fungicide formulation containing either a triazole or a strobilurin, the grain yield earned was not significantly different from the untreated plots (P > 0.05). Whereas single fungicide treatment involving a mixture of triazole and strobilurin at the optimum time gave an earning (on average 7 dt ha-1) compare to the control and a yield similar to that obtained with the double or triple fungicide treatments. [less ▲]

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See detailCartographie des périmètres irrigués de Mogtedo et de Karfiguela à l'aide de Google Earth
Dimzoure, Lamine; Wellens, Joost ULg; Tychon, Bernard ULg

Learning material (2013)

Des études diagnostics ont démontré l’absence d’une cartographie récente des périmètres irrigués rendant toute planification et gestion de l’eau aléatoire. La présente étude avait comme objectif de ... [more ▼]

Des études diagnostics ont démontré l’absence d’une cartographie récente des périmètres irrigués rendant toute planification et gestion de l’eau aléatoire. La présente étude avait comme objectif de développer une technique à moindre coût pour la cartographie des périmètres irrigués à partir de l’imagerie issue de Google Earth. Des captures d’écran, géoréférencées et mosaiquées à l’aide d’ArcGIS ,ont permis la création d’une seule image détaillée et géoréférencée par périmètre irrigué. A travers ces images détaillées, il a été possible de rapidement et clairement mettre en place un SIG et une base de données décrivant les canaux, ouvrages et parcelles des périmètres. [less ▲]

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