References of "Tychon, Bernard"
     in
Bookmark and Share    
Full Text
See detailRemote sensing assessement of irrigated areas extension in the Kou watershed
Traore, Farid ULg; Tychon, Bernard ULg

Scientific conference (2010, January 12)

The Kou watershed is a geographical space having important water resources, whose are used between: drinking water supply of Bobo-Dioulasso city (Burkina-Faso’s second most important city) and surrounding ... [more ▼]

The Kou watershed is a geographical space having important water resources, whose are used between: drinking water supply of Bobo-Dioulasso city (Burkina-Faso’s second most important city) and surrounding localities; agriculture through very important irrigated surfaces; industry; fauna and flora preservation, through a minimal sanitary debit guaranteed. Since some decades, one observes more and more increased pressure on Kou water resources. From an agricultural point of view, a comparative visual observation of irrigated surfaces during the years 1980 and during years 2000 shows an increase of surfaces. It would be then appropriate to establish a potential of irrigation of the set of available water resources in order to estimate maximal irrigable surfaces by water resources. Thus, this study has for goal the evaluation of Kou watershed irrigated zones surface, with the help of remote sensing. In order to facilitate irrigated zones detection, the study will focused on the period between January and June, where all cultures are irrigated with Kou watershed surface water and/or groundwater. The chosen methodology is images classification in order to extract irrigated zones surface. We had for this study a set of images and various data: Landsat-4 TM, Landsat-5 TM, Landsat-7 ETM+, SPOT 5, aerial views, agro meteorological data, cartographic data (GIS), data investigation reports, etc. Because of images various origins, we conducted images pretreatment that essentially consisted in image reflectance calibration. This operation appears to be indispensable when working with images from coming different sensors. Classification methods that we used are: a maximum likelihood classification, then a decision tree classification applied to images for which vegetation index (NDVI) has been calculated. The later classification method has been introduced in order to permit a better discrimination between natural vegetation and crops which can often react in similar spectral ranges. This method is based on threshold detection of vegetation classes. Classification methods used allowed us to estimate until a certain point irrigated surfaces, without having, however, a finer information. With 30 m spatial resolution images covering a survey zone with "reduced" to "mean" agricultural lands size, it is sometimes enough difficult to discern natural vegetation pixels from crop pixels. So, we should have considered mixed classes of pixels that strongly skewed our final results. The overall accuracy of our classifications are between 70% and 90%, with Kappa coefficients between 0.4 and 0.85. These Kappa coefficients our results between "tolerable" and "good". However, our evaluations seem to be near enough of those gotten by the means of hydro agricultural inventories led on the same zone. The committed mistakes remain in an interval of +/-20%. [less ▲]

Detailed reference viewed: 14 (2 ULg)
Full Text
Peer Reviewed
See detailMEASURING SOIL ORGANIC CARBON IN CROPLANDS AT REGIONAL SCALE USING AIRBORNE IMAGING SPECTROSCOPY
Stevens, Antoine; Udelhoven, Thomas; Denis, Antoine ULg et al

in Geoderma (2010), 158

Conventional sampling techniques are often too expensive and time consuming to meet the amount of data required in soil monitoring or modelling studies. The emergence of portable and flexible ... [more ▼]

Conventional sampling techniques are often too expensive and time consuming to meet the amount of data required in soil monitoring or modelling studies. The emergence of portable and flexible spectrometers could provide the large amount of spatial data needed. In particular, the ability of airborne imaging spectroscopy to cover large surfaces in a single campaign and to study the spatial distribution of soil properties with a high spatial resolution represents an opportunity for improving the monitoring of soil characteristics and soil threats such as the decline of soil organic matter in the topsoil. However, airborne imaging spectroscopy has been generally applied over small areas with homogeneous soil types and surface conditions. Here, five hyperspectral images acquired with the AHS-160 sensor (430 nm–2540 nm) were analysed with the objective to map soil organic carbon (SOC) at a regional scale. The study area, covering a surface of ∼420 km2 and located in Luxembourg, is characterized by different soil types and a high variation in SOC contents. Reflectance data were related to surface SOC contents of bare croplands by means of 3 different multivariate calibration techniques: partial least square regression (PLSR), penalized-spline signal regression (PSR) and support vector machine regression (SVMR). The performance of these statistical tools was tested under different combinations of calibration/validation sets (global and local calibrations stratified according to agro-geological zones, soil type and image number). Under global calibration, the Root Mean Square Error in the Predictions reached 5.3–6.2 g C kg−1. Under local calibrations, this error was reduced by a factor up to 1.9. SOC maps of bare agricultural fields were produced using the best calibration model. Two map excerpts were shown, which display intra- and inter-field variability of SOC contents possibly related to topography and land management. [less ▲]

Detailed reference viewed: 189 (49 ULg)
Full Text
Peer Reviewed
See detailWheat yield and PAI decreasing shape curve
Kouadio, Amani Louis ULg; Tychon, Bernard ULg

Conference (2010, January)

Estimation of cereal-crop production is considered as a priority in most crop research programmes due to the relevance of food grain to world agricultural production. Today, a large number of ... [more ▼]

Estimation of cereal-crop production is considered as a priority in most crop research programmes due to the relevance of food grain to world agricultural production. Today, a large number of agrometeorological models for crop yield assessment are available with various levels of complexity and empiricism. A preliminary study was performed with simulated data of wheat yield and LAI derived from the WOFOST/CGMS agrometeorological model. The main hypothesis underlying this study is that it’s possible to improve wheat yield estimates from metrics stretched from LAI decreasing curves. This preliminary study showed that wheat yield can be estimated by metrics stretched from simulated LAI curve-fitting done by a modified Gompertz function [G =A*exp (-exp(-k(t-m)))] and a logistic function [G = A / 1+exp(-k(t-m)); where G is the green LAI (gLAI), A the initial percentage of LAI, m the position of the inflexion point in the decreasing part of the LAI curve and k the relative senescence rate. In 2009 a large field campaign in the Grand-Duchy of Luxembourg and France was done to check the validity of such approach with field data. Hemispheric images were taken on 18 winter wheat fields during the crop cycle, preferentially from inflorescence emergence to maturity. The variable of interest, green PAI (Plant Area Index), was retrieved after analyses of images by the CAN-EYE software (v. 6.1). Data used as input to establish the model of wheat yield estimate are the value of observed PAImax, and metrics k and m, stretched from observed PAI curves fitted by Gompertz and logistic functions. The model obtained by multilinear regression with these variables reveals that wheat yield can be estimated, at the scale of the plot, with a r² ≈ 0.70 and a RMSE = 0.87 t/ha (RRMSE = 9%). The validation of such approach at the scale of an agricultural zone or region will be performed in the next step of our study, by using remote sensing data (air temperature, PAI or LAI) and phenology data as input. Such simple models may be considered as a first yield estimates that may be completed, if justified, by other agrometeorological models in order to provide a better integrated yield assessment. [less ▲]

Detailed reference viewed: 50 (9 ULg)
Full Text
Peer Reviewed
See detailModelling climate control on cropland and grassland development using phenologically tuned variables
Horion, Stéphanie; Tychon, Bernard ULg; Cornet, Yves ULg

in Geophysical Research Abstracts (2010), 12

Many studies already investigated the impact of climate change and climate variability on vegetation at global and continental scales. Using time series of remote sensing and climate data, Nemani et al ... [more ▼]

Many studies already investigated the impact of climate change and climate variability on vegetation at global and continental scales. Using time series of remote sensing and climate data, Nemani et al. (2003) analyzed trends in Net Primary Production in relation with changes in climate and showed that, between 1982 and 1999, primary productivity increased by 6% globally in response to climate change. This study also stressed the need to take into account the spatial variability of climatic constraints to plant growth when analyzing the climate change impact on vegetation. Others authors described different phenomenon linked with climate change such as increases of seasonal NDVI amplitude and growing season duration in the Northern high latitude or changes in circumpolar photosynthetic activities. Understanding the interactions between climate and vegetation is also a key issue in our PhD research. Our objective is to identify the meteorological factors which limit the development of croplands and grasslands in relation with their geographical localization. For that purpose, we acquired 10-daily time series of the Normalized Difference Vegetation Index, NDVI, derived from SPOT-VEGETATION and 7 meteorological parameters (Tmean, Tmin, Tmax, Rain, Rad, ETP, Rain-ETP) derived from ERA40 re-analyses and the operational ECMWF (European Centre for Medium-Range Weather Forecast) atmospheric model. Cross-correlations between NDVI and each one of the meteorological parameters were analysed for a set of 25 regions over Europe and Africa: 15 agricultural regions and 10 regions covered by grassland or savannas. Unlike others studies, we did not consider the vegetation globally but we focussed on two types of vegetation: croplands and grasslands. This is quite important considering the role of phenology on the vegetation cycle and its relation with climate. Moreover the analysis was not realised using yearly estimates but using 10-daily products. In order to avoid stationarity related issue, a specific methodology was developed taking into account the phenological cycle of the vegetation under consideration. Preliminary results showed that the relation between a meteorological limiting factor, e.g. precipitation, and NDVI can not be considered as linear during the year or even during the growing season. Interactions must to be studied at a smaller time scale than the growing season in order to identify properly the limiting factors to plant growth taking into account its phenology. Moreover the main limiting factors are variable from a region to another. In our analysis we also considered the possibility of a delayed response of the vegetation or a cumulated effect of meteorological events (up to 3 months). Our methodology will be presented during the conference and results will be discussed and illustrated by some test cases. [less ▲]

Detailed reference viewed: 46 (10 ULg)
Full Text
Peer Reviewed
See detailCombining remote sensing imagery of both fine and coarse spatial resolution to estimate crop evapotranspiration and quantifying its influence on crop growth monitoring
Sepulcre-Canto, Guadalupe; Gellens-Meulenberghs, Françoise; Arboleda, Alirio et al

in Geophysical Research Abstracts (2010)

This study has been carried out in the framework of the GLOBAM -Global Agricultural Monitoring system by integration of earth observation and modeling techniques- project whose objective is to fill the ... [more ▼]

This study has been carried out in the framework of the GLOBAM -Global Agricultural Monitoring system by integration of earth observation and modeling techniques- project whose objective is to fill the methodological gap between the state of the art of local crop monitoring and the operational requirements of the global monitoring system programs. To achieve this goal, the research aims to develop an integrated approach using remote sensing and crop growth modeling. This paper concerns the use of MSG geostationnary satellite data for the calculation of Actual Evapotranspiration and its integration into a crop growth model. [less ▲]

Detailed reference viewed: 38 (1 ULg)
Full Text
See detailChapter 6 : Agrometeorological forecasting
Gommes, René; Das, Haripada; Mariani, Luigi et al

in WMO/CAgM Guide to Agricultural Meteorological Practices (GAMP) WMO n° 134 (2010)

This chapter presents a set of tools and techniques for crop yield forecasting.

Detailed reference viewed: 44 (3 ULg)
Full Text
Peer Reviewed
See detailDésertification des parcours arides au Maroc
Mahyou, Hamid ULg; Tychon, Bernard ULg; Balaghi, Riad et al

in Tropicultura (2010), 28(2), 107-114

Rangeland or natural arid pastures of Morocco are ecosystems where there is a natural or seminatural vegetation composed of steppes, shrubs and grassland. They cover about 82% of the Moroccan arid lands ... [more ▼]

Rangeland or natural arid pastures of Morocco are ecosystems where there is a natural or seminatural vegetation composed of steppes, shrubs and grassland. They cover about 82% of the Moroccan arid lands. These areas represent livelihoods for thousands of people and protect the country from desertification. Despite the importance of the rangelands and the threat of desertification, it is surprising that up to date there is no comprehensive assessment of their condition and their evolution, hindering any plan for desertification alleviation. However, the available information on selected pilot areas shows that these rangelands are threatened by desertification. It’s associated with biodiversity loss and contributes to climate change. The leading causes of land degradation are the human actions combined with climate. The establishment of a comprehensive surveillance system based on remote sensing, biophysics and socio-economic data must be envisaged to provide policymakers with an operational tool adapted to the spatio-temporal monitoring of desertification. [less ▲]

Detailed reference viewed: 172 (18 ULg)
Full Text
Peer Reviewed
See detailManaging climatic risks for enhanced food security : key information capabilities
Balaghi, Riad; Badjeck, M.-C.; Djaby, Bakary ULg et al

in Procedia Environmental Sciences (2010), 1

Food security is expected to face increasing challenges from climatic risks that are more and more exacerbated by climate change, especially in the developing world. This document lists some of the main ... [more ▼]

Food security is expected to face increasing challenges from climatic risks that are more and more exacerbated by climate change, especially in the developing world. This document lists some of the main capabilities that have been recently developed, especially in the area of operational agroclimatology, for an efficient use of natural resources and a better management of climatic risks. Many countries, including the developing world, now benefit from well-trained staff in the use of climate data, physical and biological information and knowledge to reduce negative climate impacts. A significant volume of data and knowledge about climate–agriculture relationships is now available and used by students, scientists, technicians, agronomists, decision-makers and farmers alike, particularly in the areas of climate characterization, land suitability and agroecological zoning, seasonal climate forecasts, drought early warning systems and operational crop forecasting systems. Climate variability has been extensively modelled, capturing important features of the climate through applied statistical procedures, agroclimatic indices derived from raw climatic data and from remote sensing. Predictions of climate at seasonal to interannual timescales are helping decision-makers in the agricultural sector to deal more effectively with the effects of climate variability. Land suitability and agroclimatic zoning have been used in many countries for agricultural planning, thanks to the availability of new and comprehensive methodologies; developments in climate, soil and remote sensing data collection and analysis; and improved applications in geographic information systems (GIS). Drought early warning systems are available worldwide at both national and international levels. These systems are helping decisionmakers and farmers to take appropriate decisions to adapt to short-term climatic risks. Also, operational crop forecasting systems are now becoming available at the regional and national levels. In some developed countries, several efficient and well tested tools are now available for optimizing on-farm decisions based on the combination of crop simulation models and seasonal forecasts. However, in developing countries few tools have been developed to efficiently manage crops at the farm level to cope with climate variability and climate risks. Climate change impacts on agriculture and food security have been assessed in international studies using specific and efficient methodologies and tools. Adaptation to climate change and variability can also be facilitated through effective planning and implementation of strategies at the political level. The role of technological progress, risk transfer mechanisms and financial instruments and their easy accessibility to rural people are critical elements of climate risk management. [less ▲]

Detailed reference viewed: 38 (7 ULg)
Peer Reviewed
See detailExploring the potential of crop specific green area index time series to improve yield estimation at regional scale
Duveiller, Gregory; de Wit, Allard; Kouadio, Amani Louis ULg et al

in Sobrino, J. A. (Ed.) Proceedings of the 3rd International Symposium on Recent Advances in Quantitative Remote Sensing (RAQRS'III) (2010)

Crop status, such as the Green Area Index (GAI), can be retrieved from satellite observations by modelling and inverting the radiative transfer within the canopy. Providing such information along the ... [more ▼]

Crop status, such as the Green Area Index (GAI), can be retrieved from satellite observations by modelling and inverting the radiative transfer within the canopy. Providing such information along the growing season can potentially improve crop growth modelling and yield estimation. However, such approaches have proven difficult to apply on coarse resolution satellite data due to the fragmented land cover in many parts of the World. Advances in operational crop mapping will sooner or later allow the production of crop maps relatively early in the crop growth season, thereby providing an opportunity to sample pixels from medium/coarse spatial resolution data with relatively high cover fraction of a particular crop type to derive crop specific GAI time series. This research explores how to use such time series derived from MODIS to produce indicators of crop yield using two approaches over part of Belgium. The first method consists in looking at metrics of the decreasing part of the GAI curves when senescence occurs. Such metrics, like the position of the inflexion point, have been shown to be significantly correlated to yield. The second approach is to optimize the WOFOST model used in the European Crop Growth Monitoring System (CGMS) based on the GAI time series. Results show that, although the optimized model shows considerably better performance than the model running on the default parameter, the model is sometimes outperformed by the simpler metric approach. In all cases, indicators including remote sensing information provide better estimates that the average yield of previous years. [less ▲]

Detailed reference viewed: 80 (7 ULg)
Full Text
See detailGMFS Final report Stage 1 and Stage 2
Gilliams, Sven; Bydekerke, Lieven; Delrue, Josefien et al

Report (2009)

Global Monitoring for Food Security (GMFS) is a Global Monitoring for Environment and Security (GMES) Service Element (GSE) project, part of the European Space Agency (ESA) contribution to the European ... [more ▼]

Global Monitoring for Food Security (GMFS) is a Global Monitoring for Environment and Security (GMES) Service Element (GSE) project, part of the European Space Agency (ESA) contribution to the European Union (EU) /ESA GMES Programme. GMFS aims to establish an operational service for crop monitoring in support of Food Security Monitoring to serve policy makers and operational users. The GMFS project started in March 2003 as part of Stage 1 of the ESA Earthwatch GMES services Element “Service Consolidation Actions”, and was continued in October 2005 as part of the Stage 2 of the ESA Earth watch GMES services Element – “Scaling Up Consolidated GMES Services”. In this document an overview is given of the work done throughout the previous six years. GMFS aimed at monitoring crop state /vegetation condition at continental and national scale. Low resolution Earth Observation (EO) data was used for monitoring purposes at continental scale, while at national scale products were based upon medium and high resolution data, field work and agro-meteorological models. The project was guided by a project strategy group with members from the United States Agency for International Development - Famine Early Warning System Network (USAID-FEWSNET), Directorate General for Development (DG-DEV), Consultative Group on International Agricultural Research - International Wheat Improvement Center (CGIAR-CIMMYT), European Commission Joint Research Center (EC-JRC), United Nations World Food Programme (WFP) and United Nations Food and Agricultural Organisation (FAO). The goal of the project in Stage 1 (March 2003 –November 2004) was to consolidate an early warning system for food security. This started off by an intensive literature review and setting up an initial service for the Centre de Suivi Ecologique (CSE) in Dakar Senegal. In the second Phase of Stage 1 activities focussed more on the actual service delivery and setting up activities with users. Those activities included the monitoring agricultural production for Senegal, monitoring agriculture in Malawi and giving support to the Crop and Food Supply Assessment Mission (CFSAM) of FAO /WFP. Additionally, services were set up for the centre Agro-Hydro-Météorologique (AGRHYMET) as a result of a meeting between AGHRYMET and Vlaamse Instelling voor Technologisch Onderzoek (VITO). During 2005 the early warning service was continued to support GMFS users although there was at that time no formal contract to do so. At the start of the Second Stage, in October 2005, a GMFS user executive board, consisting of one representative from: EC-JRC, FAO, WFP, Southern Africa Development Community Regional Remote Sensing Unit (SADC-RRSU), Regional Centre for Mapping of Resources for Development (RCMRD) and AGRHYMET, was set up to support the consortium in defining the correct services and to review the work. Since the focus for the Second Stage was on up scaling the consolidated services, it was decided that the early warning service and support to the CFSAM were to be continued, the agricultural mapping service was to be expanded to more countries - namely, Senegal, Sudan, Ethiopia, Malawi and Zimbabwe - and extra services on yield modeling using remote sensing and agro-meteorological models were to be provided. During the second year of this stage, the services were even more extended with, support to the Ministry of Agriculture and Meteorological Department in Mozambique, extra activities in Ethiopia and Sudan and support to the regional centers on operational use of the ESA Data Dissemination System (DDS). [less ▲]

Detailed reference viewed: 32 (0 ULg)
Full Text
Peer Reviewed
See detailAssessing the Accuracy of Simulation Model for Septoria Leaf Blotch Disease Progress on Winter Wheat.
El Jarroudi, Moussa ULg; Delfosse, Philippe; Maraite, Henri et al

in Plant Disease (2009), 93

A mechanistic model, PROCULTURE, for assessing the development of each of the last five leaf layers and the progress of Septoria leaf blotch, caused by Septoria tritici (teleomorph Mycosphaerella ... [more ▼]

A mechanistic model, PROCULTURE, for assessing the development of each of the last five leaf layers and the progress of Septoria leaf blotch, caused by Septoria tritici (teleomorph Mycosphaerella graminicola), has been applied on susceptible and weakly susceptible winter wheat (Triticum aestivum) cultivars in two locations (Everlange and Reuland) in Luxembourg over a 3-year period (2000 to 2002). A double performance assessment of PROCULTURE was conducted in this study. First, the capability of PROCULTURE to correctly simulate S. tritici incidence was checked. Second, the model's ability to accurately estimate disease severity was assessed on the basis of the difference between simulated and observed levels of disease development at each leaf layer. The model accurately predicted disease occurrence in the 2000 and 2002 seasons, on susceptible and semi-susceptible cultivars, with a probability of detection (POD) exceeding 0.90. However, in 2001, even though the POD never fell below 0.90, the false alarm ratio (FAR) was too high to consider the simulations satisfactory. Concerning the evaluation of disease severity modeling, statistical tests revealed accurate simulations performed by PROCULTURE for susceptible cultivars in 2000 and 2002. By contrast, for weakly susceptible cultivars, the model overestimated disease severity, especially for the upper leaves, for the same period. [less ▲]

Detailed reference viewed: 60 (8 ULg)
Full Text
See detailBulletin agrométéorologique - Situation au 31 août 2009
Tychon, Bernard ULg; Scohy, Laureline; Denis, Antoine ULg et al

in Bulletin Agrométéorologique (2009), 7(3), 1-4

Les conditions atmosphériques de juillet et août ont permis aux cultures d’hiver de boucler leurs cycles dans d’excellentes conditions. Pour les cultures de printemps par contre, le mois d’août chaud et ... [more ▼]

Les conditions atmosphériques de juillet et août ont permis aux cultures d’hiver de boucler leurs cycles dans d’excellentes conditions. Pour les cultures de printemps par contre, le mois d’août chaud et sec aura pu accélérer la sénescence et créer ça et là des stress hydriques en particulier pour le maïs et la pomme de terre qui sont plus sensibles à la sécheresse que la betterave. Les rendements prédits pour la pomme de terre sont en-dessous de la moyenne, ils sont proches de la moyenne pour le maïs tandis qu’ils sont largement supérieurs pour la betterave. Des différences parfois importantes sont simulées entre les différentes régions agricoles. [less ▲]

Detailed reference viewed: 9 (1 ULg)
Full Text
Peer Reviewed
See detailFirst Report of Wheat Leaf Rust in the Grand Duchy of Luxembourg and the Progress of its Appearance over the 2003–2008 Period
El Jarroudi, Moussa ULg; Giraud, Frédéric; Vrancken, Carine et al

in Plant Disease (2009), 93

Wheat leaf rust caused by Puccinia triticina Eriks. was identified for the first time in 2000 in the Grand Duchy of Luxembourg on the basis of orange-to-brown, round-to-ovoid, erumpent uredinia (1 to 1.5 ... [more ▼]

Wheat leaf rust caused by Puccinia triticina Eriks. was identified for the first time in 2000 in the Grand Duchy of Luxembourg on the basis of orange-to-brown, round-to-ovoid, erumpent uredinia (1 to 1.5 mm in diameter) scattered on the upper and lower leaf surfaces and producing orange-brown urediniospores that are subgloboid, approximately 20 μm in diameter, and with up to eight germ pore scattered in thick, echinulate walls. In a second phase, wheat was monitored weekly (starting from Zadoks growth stage 30, pseudo stem erection) during the 2003–2008 cropping seasons for wheat leaf rust. Disease severity (percentage of leaf area with symptoms) was recorded in four, replicated field experiments located in three villages (Diekirch District: Reuler; and Grevenmacher District: Burmerange and Christnach), which are representative of the different agroclimatological zones of Luxembourg. A significant difference in severity was observed between the sites (P < 0.01) and the years (P < 0.05). Over the 6-year period, Burmerange and Reuler consistently showed the highest and lowest disease severity, respectively. In 2003 and 2007, Burmerange (a southern site with the highest average spring temperatures of 13.6 and 14.0°C, respectively) showed the highest disease severity with 66 and 57%, respectively, whereas the lowest severity (<1% for both years) was observed in the north at Reuler (site with the lowest average spring temperatures of 12.0 and 12.4°C, respectively). Christnach, located midway between Reuler and Burmerange, showed an intermediate disease severity with 7% (2003) and 22% (2007). The disease appeared at growth stages 77 (late milk) and 87 (hard dough) in the period 2003–2005, but at an earlier stage (45, boots swollen) for 2006–2008 (P < 0.001). In 2005, low severity was recorded due to a severe drought during May, June, and July. A reason for this earlier appearance of leaf rust occurrences in the two districts may be related to an increase in the average spring temperature (average March to May temperature for Luxembourg was 8.3°C for the 1971–2000 period, 9.5°C for the 2003–2005 period, 9.9°C for the 2006–2008 period, 2007 was exceptional with 11.9°C, P < 0.01). In the past, cereal disease management strategies were oriented toward the control of predominant and yield-reducing diseases such as that caused by Septoria tritici Desm. Because the succession of mild winters and warm springs during the last 5 years allowed the early occurrence and the fast development of wheat leaf rust in the Grand Duchy of Luxembourg, it is advisable to take this disease into account in fungicide application schemes. [less ▲]

Detailed reference viewed: 40 (2 ULg)
Peer Reviewed
See detailIMPROVING SOIL ORGANIC CARBON (SOC) PREDICTION BY FIELD SPECTROMETRY IN BARE CROPLAND BY REDUCING THE DISTURBING EFFECT OF SOIL ROUGHNESS
Denis, Antoine ULg; Tychon, Bernard ULg; Stevens, Antoine et al

in Geoscience and Remote Sensing Symposium, 2009 IEEE International, IGARSS 2009 (2009, July 17)

The spatial estimation of Soil Organic Carbon (SOC) at large scale in outdoor condition is an important issue. It has been largely demonstrated that diffuse reflectance spectroscopic techniques, are ... [more ▼]

The spatial estimation of Soil Organic Carbon (SOC) at large scale in outdoor condition is an important issue. It has been largely demonstrated that diffuse reflectance spectroscopic techniques, are efficient for SOC determination in field conditions. However these methods are influenced by disturbing factors such as soil water content, vegetation residues and surface roughness, the later being the object of this study. Our laboratory experiments showed that the accuracy of SOC prediction from shadowed soil samples with spectroscopy techniques decreases with increasing soil shadow. In this study a new methodology using a digital camera for identifying and correcting the effect of soil shadow on field reflectance spectra measured with an Analytical Spectral Devices (ASD) during field campaign in bare crop lands has been elaborated and tested. Results showed that the proposed shadow correction method enables improving significantly SOC prediction accuracy and performs better than traditionally used methods consisting in automatic signal processing. [less ▲]

Detailed reference viewed: 85 (29 ULg)
Full Text
See detailBulletin agrométéorologique - Situation au 21 juin 2009
Tychon, Bernard ULg; Scohy, Laureline; Denis, Antoine ULg et al

in Bulletin Agrométéorologique (2009), 7(2), 1-5

Depuis le dernier bulletin publié fin avril, les conditions météorologiques ont été fort proches des normales avec toutefois quelques épisodes orageux qui ont pu causer ça et là des dégâts aux cultures ... [more ▼]

Depuis le dernier bulletin publié fin avril, les conditions météorologiques ont été fort proches des normales avec toutefois quelques épisodes orageux qui ont pu causer ça et là des dégâts aux cultures. La végétation semble avoir ralenti davantage sa croissance que ce qui s’observe d’habitude depuis dix ans, cela en particulier dans le Nord et le Nord-Ouest du pays, probablement en raison des conditions pluvieuses rencontrées dans ces zones. Cependant les prévisions de rendements à l’échelle nationale ne semblent pas être affectées. A l’exception du maïs, les rendements s’annoncent meilleurs que la moyenne des quatre dernières années. [less ▲]

Detailed reference viewed: 13 (0 ULg)
Full Text
See detailBulletin agrométéorologique - Situation au 30 avril 2009
Tychon, Bernard ULg; Djaby, Bakary ULg; Denis, Antoine ULg et al

in Bulletin Agrométéorologique (2009), 7(1), 1-3

Alors que l’on pouvait craindre les conséquences de l’hiver froid que nous avons connu cette année, il apparaît, au niveau de nos indicateurs météorologiques et de nos indicateurs spatiaux dérivés de la ... [more ▼]

Alors que l’on pouvait craindre les conséquences de l’hiver froid que nous avons connu cette année, il apparaît, au niveau de nos indicateurs météorologiques et de nos indicateurs spatiaux dérivés de la télédétection, que les grandes cultures ont dans l’ensemble bien passé l’hiver et elles ont largement rattrapé le retard accumulé au cours des mois d’hiver et du tout début de printemps. Ceci se vérifie également sur le terrain où les stades phénologiques sont très proches de la situation normale. Aucune prévision de rendement n’est faite à ce stade. [less ▲]

Detailed reference viewed: 12 (2 ULg)
Full Text
See detailUtilisation des prises de vue aériennes à basse altitude pour le suivi des activités hydro-agricoles - Cas du bassin du Kou (Burkina Faso)
Wellens, Joost; Diallo, Mamadou; Dakoure, Denis et al

Poster (2009, March 19)

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 hydro-agricoles recensés couvrent une superficie totale de près de 3.200 ha ; il s’agit pour l’essentiel de périmètres privés formant la ceinture maraîchère et horticole 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. Le développement d’une filière fruits et légumes sous l’impulsion de l’initiative privée est un trait caractéristique de la production irriguée dans la région. 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 suite à l’extension non contrôlée de l’agriculture irriguée. Ceci a conduit les gestionnaires du bassin à rechercher des outils de contrôle et de suivi. A partir de plus de 300 prises de vue aérienne ‘amateurs’ à basse altitude, ayant une résolution de 0,8 m., une image d’occupation détaillée des sols a pu être élaborée. Des logiciels de mosaïquage, de traitement d’images et de SIG ont permis la construction d’une seule image géoréférencée. Les parcelles agricoles irriguées ont ainsi pu être délimitées. Leurs occupations ont été comparées et complétées avec les résultats d’un recensement hydro-agricole exhaustif organisé au même moment. Cette technique permet un suivi spatial des activités agricoles à moindre coût par rapport à l’acquisition des images satellites à haute résolution. L’approche est également moins sensible aux influences atmosphériques non-prévisibles dans la programmation des images satellites. Elle répond avec une précision largement suffisante aux objectifs de suivi et contrôle des parcelles irriguées demandés par les gestionnaires du bassin. [less ▲]

Detailed reference viewed: 74 (16 ULg)
Full Text
See detailSet-up of CGMS in Ethiopia and first user experiences
Djaby, Bakary ULg; Tychon, Bernard ULg; Massart, Michel

Conference (2009, March 18)

Detailed reference viewed: 29 (12 ULg)
Full Text
Peer Reviewed
See detailFirst report of wheat powdery mildew and its severity in the Grand-Duchy of Luxembourg over the 2003-2009 period
El Jarroudi, Moussa ULg; Giraud, Frédéric; Tychon, Bernard ULg et al

in Journal of Plant Pathology [=JPP] (2009), 91(S4), 109

Detailed reference viewed: 45 (11 ULg)