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See detailMonitoring of the crop water stress in Belgium. The case of the 2003 heat wave.
Horion, Stéphanie; Tychon, Bernard ULiege; De Longueville, Florence ULiege

Conference (2006, October)

In this paper the crop water stress is evaluated with three different indices: (i) the Relative Soil Moisture Index [RSMI] resulting from agrometeorological model simulations, (ii) the Normalized ... [more ▼]

In this paper the crop water stress is evaluated with three different indices: (i) the Relative Soil Moisture Index [RSMI] resulting from agrometeorological model simulations, (ii) the Normalized Difference Vegetation Index, [NDVI] applied on S10 SPOT-VGT imagery, (iii) the Normalized Difference Water Index, [NDWI] applied on S10 SPOT-VGT imagery. The RSMI is one of the outputs of the Belgian Crop Growth Monitoring System. It indicates the soil water availability for crops. Crop water stress is assumed when soil water availability is lower than the crop potential evapotranspiration. One of the potential applications for drought monitoring is the calculation of the number of days with a crop water stress during the growing season or more precisely during the “moisture-sensitive period” of the crop. The two others (well-known) indices are derived from low resolution satellite imagery. Complete time series of S10 SPOT-VGT NDVI and NDWI data - i.e. from April 1998 onwards – have been acquired for the research. Using spatial information on land-uses in Belgium, a simple unmixing method is implemented to partly reduce the problem of mixed values occurring inevitably in 1x1km² pixels. Only the most agricultural pixels are considered for the analysis. The heat wave occurred during the summer 2003 has been chosen as a study case for the comparison. This summer was particularly hot, dry and sunny with the highest averaged temperature ever recorded from June to August in Uccle-Belgium. Many human activities were affected by this particular climatic condition, among which agriculture. In order to make the comparison possible, a standardization of the outputs of the 3 indexes is realised, taking into account the times series of each indexes. Moreover all the outputs are aggregated at municipality level. [less ▲]

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See detailGreen leaf area decline of wheat top three leaves in Belgium and G-D of Luxembourg from 2003 to 2006 : the relationships with grain yield.
Martin, B.; Tychon, Bernard ULiege; El Jarroudi, Moussa ULiege et al

Conference (2006, October)

The modified Gompertz model developed by Gooding et al. (2000) was used to describe the decline in green area of wheat top three leaves in field experiments where green leaf area at time t = 100*exp[-exp ... [more ▼]

The modified Gompertz model developed by Gooding et al. (2000) was used to describe the decline in green area of wheat top three leaves in field experiments where green leaf area at time t = 100*exp[-exp(-k*(t-m))]. In the absence of fungicide, green leaf area decline was associated with drought or infection with a number of foliar pathogens including Septoria tritici (sexual stage Mycospherella graminicola) and Puccinia recondita f.sp. tritici and Erysiphe graminis. On the whole experiments and cultivars there was no effect of fungicide on k but it was highly significant on m (P<0.001). When main effects are considered, fungicide delayed green leaf area decline rather than reduced its rate of progress once started. Fungicide had variable effects on grain yield, largely reflecting variation in disease infection pressures in the different years and susceptibility of the different cultivars. If no correlation was observed between k values and grain yields, m was at the contrary very closely associated with grain yields. This study supports the view of Gooding (2000) and Gaunt (1995) that, for many diseases, effects on green area duration give an adequate estimate of host yield reduction. Therefore we have use the close relationship between the parameter m of the Gompertz model and grain yield to improve the Belgium-Crop Growth Monitoring System (B-CGMS) by recalibrating LAI evolution simulated by B-CGMS according to the evolution of LAI derived from the Gompertz model. The system includes indeed a component allowing taking into account senescence in the evolution of LAI during the growing season. Recalibration has been realized through the modification of one of the parameters influencing the leaf senescence, the SPAN parameter. Modifying the SPAN parameter comes down to modify the lifespan of leaves. Considering that parasitic pressure reduces leaves lifespan and therefore the photosynthetic capacity, this approach makes it possible to take into account the influence of this pressure on yield predictions in the Belgian Crop Growth Monitoring System. [less ▲]

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See detailThe B-CGMS project : evaluation after 5 years of monitoring and prediction
Curnel, Y.; Oger, Robert ULiege; Leteinturier, B. et al

Conference (2006, October)

The B-CGMS project, started in 1998, is the adaptation to Belgian Conditions of the European Crop Growth Monitoring System (CGMS). This project involved 3 Belgian scientific institutes: the Walloon ... [more ▼]

The B-CGMS project, started in 1998, is the adaptation to Belgian Conditions of the European Crop Growth Monitoring System (CGMS). This project involved 3 Belgian scientific institutes: the Walloon agricultural research Centre (CRA-W), the Flemish Institute for Technological Research (VITO) and the University of Liège (ULg). The main difference with the European system is that more detailed inputs (meteorological, soil and NUTS inputs) are used. Crop yields predictions are realised on a monthly basis during the growing season (from April to September) for 6 crops (winter wheat, winter barley, maize, Potato, sugar beet, winter rapeseed). Yields predictions as well as analyses of meteorological situation of the month and RS information on the state of the crops are published in agrometeorological bulletins sent by e-mail since 2002. The information is also available on the Internet website of the project (http://.b-cgms.cra.wallonie.be). Crop yields predictions are produced through a combination of linear regression models which may include different categories of yield indicators (trend, meteo, RS and agrometeorological model outputs). Crop yields predictions procedure is currently semi-automated by the use of a statistical calibration toolbox (StatCaT). The evaluation of the project after 5 years of monitoring and prediction has first shown that final yields predicted B-CGMS as well as the ones predicted by MARS are coherent compared with official yields: no significant differences are observed. As far as the accuracy according to the month for which the prediction is made is concerned, we can notice that at agricultural circumscriptions level and for winter crops a lower precision of B-CGMS is observed before June and that there is no improvement in July (in comparison with June). The same evolution is observed for summer crops before July but in August and September, the prediction accuracy decreases. Even if calibration models present high adjusted coefficient of determination, the technological trend explains an important part of the variability and it is therefore necessary to consider the effect of a year factor on the quality of prediction in order to clearly the interest of the agrometeorological model. For some crops (as potato), adding agrometeorological yield outputs to models including already the technological trend allow to improve the quality of prediction especially for “extreme” year i.e. years where official yields move away significantly from the technological trend. For others crops as winter wheat, this improvement of the quality of prediction is not observed. However, fortunately, adding other yield indicators as meteo indicators can improve in general the quality of prediction and once again especially for “extreme” years. [less ▲]

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See detailDownscaling of ECMWF grid meteorological data : comparison with ground stations and validation
Tychon, Bernard ULiege; Horion, Stéphanie

Conference (2006, October)

CGMS currently operates on observed station data. Switching from this classical approach to a modelled data from European Centre for Medium-range Weather Forecast, ECMWF, has to be tested before applying ... [more ▼]

CGMS currently operates on observed station data. Switching from this classical approach to a modelled data from European Centre for Medium-range Weather Forecast, ECMWF, has to be tested before applying it operationally. In this study, we concentrated on the impact of the downscaling of meteorological data with grid sizes ranging from 1.875 to 0.35 degrees to the new CGMS grid size of 25 X 25 km. Four different grid sizes corresponding respectively to the dimensions of the Operational, EPS, Monthly and Seasonal ECMWF Models were checked. The control was done on daily data of 25 stations selected on a 2-year period in a window covering the South of Germany and Czech Republic, a large part of Austria and the North of Italia in order to analyse the downscaling impact on plains, mountainous and coastal zones. For each grid size, four different downscaling methods were applied: the reference method that uses the classical CGMS interpolation procedure, the nearest neighbour approach, and two more complicated interpolation techniques using the Model Output Statistics developed by Meteo Consult (MC-MOS). The analysis showed that the accuracy of the downscaling procedure is largely influenced by the input data grid size. RMSE increases between the smallest and the largest grids are respectively 59%, 51%, 33%, and 33% for Tmax, Tmin, Wind Speed and Radiation fields. Rainfall does not seem to be affected by the downscaling process but the RMSE is high in all cases. In most cases, the best interpolation method is also the more complex one and the one that requires more computer time to be calculated. RMSE decrease of 22%, 50%, 57% and 28% respectively for Tmax, Tmin, Wind speed and Radiation fields when we compare the best interpolation method results with the reference approach. An exception in this general rule is for the rainfall rate estimation whose accuracy is not always best with the most complex interpolation technique. [less ▲]

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See detailEmpirical regression models using NDVI, rainfall and temperature data for the early prediction of wheat grain yields in Morocco
Balaghi, Riad; Tychon, Bernard ULiege; Eerens, H. et al

Conference (2006, October)

In Morocco, no operational system actually exists for the early prediction of the grain yields of bread wheat. This study proposes empirical Ordinary Least Squares regression models to forecast the yields ... [more ▼]

In Morocco, no operational system actually exists for the early prediction of the grain yields of bread wheat. This study proposes empirical Ordinary Least Squares regression models to forecast the yields at provincial and national levels. The predictions were based on dekadal (10-daily) NDVI/AVHRR, dekadal rainfall sums and average monthly air temperatures. The global land cover map GLC2000 was used to select only the NDVI pixels that are related to agricultural lands. Provincial yields were assessed with errors varying from 80 to 762 kg.ha-1, depending on the province. At national level, yield was predicted at the third dekad of April with 73 kg.ha-1 error, using NDVI and rainfall. However, earlier forecasts are possible, starting from the second dekad of March with 84 kg.ha-1 error. At the province and country levels most of the yield variation was accounted for by NDVI. The proposed models can be used in an operational context to forecast bread wheat yields in Morocco. [less ▲]

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See detailBulletin agrométéorologique - Août 2006
Tychon, Bernard ULiege; Ozer, Pierre ULiege; De Longueville, Florence ULiege et al

in Bulletin Agrométéorologique (2006), 5(5),

L’année 2006 restera dans les annales comme étant une année exceptionnelle au niveau météorologique tant par son printemps froid que par son mois de juillet très sec et son mois d’août particulièrement ... [more ▼]

L’année 2006 restera dans les annales comme étant une année exceptionnelle au niveau météorologique tant par son printemps froid que par son mois de juillet très sec et son mois d’août particulièrement pluvieux. Ces conditions exceptionnelles rendent très délicates les prévisions de rendement. Il faut signaler que les rendements estimés sont ceux sur pieds et ils ne prennent pas en considération les pertes dues aux mauvaises conditions de récolte. Les rendements prévus pour les principales cultures de printemps restent très proches des moyennes calculées sur les 5 dernières années. [less ▲]

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See detailBulletin agrométéorologique - Juillet 2006
Tychon, Bernard ULiege; Ozer, Pierre ULiege; De Longueville, Florence ULiege et al

in Bulletin agrométéorologique (2006), 5(4), 1-6

Le mois de juillet fut exceptionnellement chaud et sec jusqu’à la dernière semaine de juillet. Cette période sèche, dans la prolongation de celle du mois de juin, a pu entraîner des chutes de rendements ... [more ▼]

Le mois de juillet fut exceptionnellement chaud et sec jusqu’à la dernière semaine de juillet. Cette période sèche, dans la prolongation de celle du mois de juin, a pu entraîner des chutes de rendements de certaines cultures en phases sensibles en particulier là où la nature des sols n’a pas pu répondre aux besoins en eau des cultures. La situation des cultures reste cependant globalement favorable, laissant entrevoir des rendements généralement supérieurs à la moyenne des cinq années précédentes. [less ▲]

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See detailBulletin agrométéorologique - Juin 2006
Tychon, Bernard ULiege; Ozer, Pierre ULiege; De Longueville, Florence ULiege et al

in Bulletin Agrométéorologique (2006), 5(3), 1-7

Le mois de juin fut chaud permettant à la plupart des cultures de bénéficier de très bonnes conditions de croissance. Le retard de croissance observé depuis le début du suivi des cultures a quasi ... [more ▼]

Le mois de juin fut chaud permettant à la plupart des cultures de bénéficier de très bonnes conditions de croissance. Le retard de croissance observé depuis le début du suivi des cultures a quasi complètement disparu. La faible pluviométrie constatée au mois de juin n’a pour l’instant que peu de conséquences pour les cultures bien installées vu les réserves en eau accumulées le mois précédent. La situation des cultures est globalement favorable, laissant entrevoir des rendements généralement supérieurs à la moyenne des cinq années précédentes. Toutefois, cette prévision pourrait être revue à la baisse si la période sèche observée en juin se prolongeait en juillet. [less ▲]

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See detailBulletin agrométéorologique - Mai 2006
Tychon, Bernard ULiege; De Longueville, Florence ULiege; Ozer, Pierre ULiege et al

in Bulletin Agrométéorologique (2006), 5(2), 1-5

Des précipitations fortement excédentaires ont été enregistrées au mois de mai, particulièrement dans la deuxième quinzaine. Le rayonnement fut très anormalement inférieur à la moyenne et les températures ... [more ▼]

Des précipitations fortement excédentaires ont été enregistrées au mois de mai, particulièrement dans la deuxième quinzaine. Le rayonnement fut très anormalement inférieur à la moyenne et les températures, bien qu’en moyenne proche de la normale, ont été basses dans la dernière décade. Le retard accusé par la végétation depuis le début de la saison n’a pas encore été entièrement résorbé. La situation des cultures est globalement favorable, laissant entrevoir des rendements généralement supérieurs à la moyenne des cinq années précédentes. [less ▲]

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See detailBulletin agrométéorologique - Avril 2006
Tychon, Bernard ULiege; De Longueville, Florence ULiege; Ozer, Pierre ULiege et al

in Bulletin Agrométéorologique (2006), 5(1), 1-5

L’hiver météorologique (décembre 2005 à février 2006) peut être caractérisé de normal. Les mois de mars et avril furent plus froids que la normale et cela a pour conséquence un retard phénologique évalué ... [more ▼]

L’hiver météorologique (décembre 2005 à février 2006) peut être caractérisé de normal. Les mois de mars et avril furent plus froids que la normale et cela a pour conséquence un retard phénologique évalué à 10 – 15 jours selon les endroits. Les prévisions de rendement annoncent pour les cultures d’hiver, des rendements équivalent ou légèrement supérieurs à 2005 mais inférieurs à ceux de 2004. Il est prématuré d’émettre des prévisions pour les cultures printanières. [less ▲]

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See detailRenforcement structurel de la capacité de gestion des ressources en eau pour l'agriculture dans le bassin du Kou (Burkina Faso): Rapport Technique 2 (2005-2006)
Wellens, Joost ULiege; Tychon, Bernard ULiege; Traore, Farid et al

Report (2006)

Le bassin du Kou, situé dans le sud-ouest du Burkina Faso, est depuis quelques décennies le théâtre de différentes formes de conflits liés à toute une série de problèmes que l’on rencontre généralement ... [more ▼]

Le bassin du Kou, situé dans le sud-ouest du Burkina Faso, est depuis quelques décennies le théâtre de différentes formes de conflits liés à toute une série de problèmes que l’on rencontre généralement dans des zones irriguées. Dans le bassin du Kou, les aménagements hydroagricoles recensés couvrent une superficie totale de près de 3.200 ha. Il s’agit pour l’essentiel de périmètres privés formant la ceinture maraîchère, horticole et fruitière de Bobo-Dioulasso et d’un grand périmètre de 1.200 ha réalisé par l’Etat à Bama et spécialisé dans la production du riz. Outre l’abondance en eau liée à la présence de sources importantes, d’une nappe phréatique facilement exploitable, d’un cours d’eau pérenne et un hivernage à caractère sub-humide, la plupart des utilisateurs d’eau se retrouvent régulièrement en pénurie d’eau à cause d’une augmentation de la population et d’une intensification de l’agriculture irriguée. Ceci conduit les gestionnaires du bassin à rechercher des outils de contrôle et de suivi. [less ▲]

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See detailRelationship between the progress of the foliar pathogens caused by Septoria tritici and the reduction of the photosynthetic vitality of plants in Grand-Duchy of Luxembourg in 2004.
El Jarroudi, Moussa ULiege; Crumière, F.; Hausman, J.-F. et al

in Bibliotheca fragmenta agronomica - Book of proceedings (2006), 11(2), 643-644

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See detailGreen leaf area decline of wheat top three leaves in Belgium and G-D of Luxembourg from 2003 to 2005 : the relationships with grain yield.
Martin, B.; El Jarroudi, Moussa ULiege; Tychon, Bernard ULiege

in Bibliotheca fragmenta agronomica - Book of proceedings (2006), 11(1), 167-168

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See detailCrop yield forecast with NOAA and spot-vegetation data in Morocco.
Balaghi, Riad; Tychon, Bernard ULiege; Eerens, H. et al

Conference (2006)

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See detailProtection and maintenance of permanent pastures
Gobin, B.; Brodsky, L.; Tychon, Bernard ULiege et al

in Kay, Simon; Sima, Aleksandra; Loudjani, Philippe (Eds.) Proceedings of the 12th MARS PAC Annual Conference, 2006 (2006)

All farmers receiving direct payments are subject to compulsory cross-compliance which includes standards related to the maintenance and protection of permanent pastures. Questionnaire techniques and ... [more ▼]

All farmers receiving direct payments are subject to compulsory cross-compliance which includes standards related to the maintenance and protection of permanent pastures. Questionnaire techniques and spatio-temporal analyses demonstrated that the ratio of permanent pasture area to agricultural land provides a simple tool for monitoring and controlling the protection of permanent pastures at the regional to Member State level. Huge variations in the ratio across Europe were related to the importance of permanent pastures, the interpretation of definitions, sources of information used, differences in calculation, and the presence of protective and/or sensitive zones. Precautionary or complementary measures are in place in most Member States in order to prevent decreases in the ratio. The implementation of GAEC standards related to permanent pastures overlaps with the standard management requirements, national legislation and current agri-environmental programmes. The study advocates the establishment of a comprehensive geo-information platform consisting of a topologically correct inventory of all permanent pasture parcels in a 1:1 geo-referenced relation between IACS and LPIS; ancillary spatially explicit data such as orthophotos, remote sensing images and other thematic geo-databases; and, geodatabases with parcel information compiled for other monitoring purposes such as those within the framework of the Nitrates Directive or 2nd pillar support. [less ▲]

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See detailForecasting Septoria tritici on winter wheat in the Grand-Duchy of Luxembourg from 2000 to 2005.
El Jarroudi, Moussa ULiege; Tychon, Bernard ULiege; Maraite, H. et al

in Bibliotheca Fragmenta Agronomica - Book of Proceedings (2006), 11(2), 751-752

This papers presents the results of a wheat diseases model called PROCULTURE for the prediction of septoriosis in the Grand Duchy of Luxembourg

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See detailDetection of carbon stock change in agricultural soils using spectroscopic techniques
Stevens, Antoine; Van Wesemael, Bas; Vandenschrick, Grégoire et al

in Soil Science Society of America Journal (2006), 70(3, MAY-JUN), 844-850

Soil organic carbon (SOC) represents one of the major pools in the global C cycle. Therefore, even small changes in SOC stocks cause important CO, fluxes between terrestrial ecosystems and the atmosphere ... [more ▼]

Soil organic carbon (SOC) represents one of the major pools in the global C cycle. Therefore, even small changes in SOC stocks cause important CO, fluxes between terrestrial ecosystems and the atmosphere. However, SOC stocks are difficult to quantify accurately due to their high spatial variability. The aim of this paper is to evaluate the potential of Imaging Spectroscopy (IS) using the Compact Airborne Spectrographic Imager (CASI; 405-950 nm) and field spectroscopy with an Analytical Spectral Devices spectrometer (ASD; 350-2500 nm) to measure SOC content in heterogeneous agricultural soils. We used both stepwise and partial least square (PLS) regression analysis to relate spectral measurements to SOC contents. Standard Error of Prediction (SEP) for the ASD ranged from 2.4 to 3.3 g C kg(-1) depending on soil moisture content of the surface layer. Imaging spectroscopy performed poorly, mainly due to the narrow spectral range of the CASI. Tests using both the CASI and the Shortwave infrared Airborne Spectrographic Imager (SASI; 900-2500 nm) showed better results. The variation in soil texture and soil moisture content degrades the spectral response to SOC contents. Currently, SEP allows to detect a SOC stock change of 7.2-9.9 Mg C ha(-1) in the upper 30 cm of the soil, and is therefore still somewhat high in comparison with changes in SOC stocks as a result of management or land conversion (0.34.9 Mg C ha(-1) yr(-1)). A detailed SOC maps produced by IS reflected the patterns in SOC contents due to the recent conversion from grassland to cropland. [less ▲]

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See detailCGMS/WOFOST model principles
Tychon, Bernard ULiege

Conference (2005, November)

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See detailBulletin agrométéorologique - Septembre 2005
Tychon, Bernard ULiege; Ozer, Pierre ULiege; De Longueville, Florence ULiege et al

in Bulletin Agrométéorologique (2005), 4(5), 1-3

Le mois de septembre fut anormalement chaud et ensoleillé. Les précipitations furent par contre inférieures à la moyenne. A ce stade-ci de l’année, seules les prévisions relatives aux rendements du maïs ... [more ▼]

Le mois de septembre fut anormalement chaud et ensoleillé. Les précipitations furent par contre inférieures à la moyenne. A ce stade-ci de l’année, seules les prévisions relatives aux rendements du maïs fourrager et de la betterave sucrière sont calculées. Par rapport à l’année dernière et, sur l’ensemble du territoire, les prévisions de rendements de la betterave sucrière sont équivalentes, tandis que celles du maïs sont légèrement à la baisse. [less ▲]

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See detailBulletin agrométéorologique - Août 2005
Tychon, Bernard ULiege; Ozer, Pierre ULiege; De Longueville, Florence ULiege et al

in Bulletin Agrométorologique (2005), 4(5), 1-4

Le mois d’août a été caractérisé par des valeurs climatiques proches de la normale. Cependant, les températures et les valeurs de rayonnement étaient anormalement faibles. Par rapport à l’année dernière ... [more ▼]

Le mois d’août a été caractérisé par des valeurs climatiques proches de la normale. Cependant, les températures et les valeurs de rayonnement étaient anormalement faibles. Par rapport à l’année dernière et, sur l’ensemble du territoire, les prévisions de rendements des principales cultures printanières sont équivalentes dans le cas de la betterave sucrière, et à la baisse pour le maïs fourrager et la pomme de terre Bintje. [less ▲]

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