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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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See detailMonitoring the evolution of irrigated areas with Landsat images using backward and forward change detection analysis in the Kou watershed
Traore, Farid ULg; Cornet, Yves ULg; Denis, Antoine ULg et al

in Geocarto International (2013)

The Kou watershed is characterized by important water resources used for drinking, agriculture (especially in the important irrigated areas), industry and the preservation of aquatic fauna and flora. For ... [more ▼]

The Kou watershed is characterized by important water resources used for drinking, agriculture (especially in the important irrigated areas), industry and the preservation of aquatic fauna and flora. For several decades there has been increasing pressure on the Kou’s water resources, partly because of the expansion of the irrigated agricultural areas. This study was conducted to examine this issue, focusing on one specific irrigated area. In order to monitor the expansion of irrigated areas in developing countries, a low-cost remote sensing method based on Landsat images and aerial photographs was developed. The method is based on maximum-likelihood classifications, followed by backward and forward change detection analysis requiring agronomic expertise. Using pixel trajectory analysis, the method connects all pixels to their consecutive states in order to correct their current states. The study showed that the irrigated area has expanded by almost 80% over 20 years, with most of this expansion occurring in the past 10 years. The approach, if validated, could be used to obtain information on past occupation in the rural irrigated areas for which there is no archived data. [less ▲]

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See detailA framework for the use of decision-support tools at various spatial scales for the management of irrigated agriculture in West-Africa
Wellens, Joost ULg; Traore, Farid; Diallo, Mamadou et al

in Agricultural Sciences (2013), 4 (8A)

The Kou watershed in south-western Burkina Faso has suffered from poor water management for several decades. Covering 1,800 km², this small watershed is the site of the second largest city in Burkina Faso ... [more ▼]

The Kou watershed in south-western Burkina Faso has suffered from poor water management for several decades. Covering 1,800 km², this small watershed is the site of the second largest city in Burkina Faso (Bobo-Dioulasso), a former State-run irrigated rice scheme and several informal agricultural zones. Notwithstanding the abundance of water resources, most water users regularly face water shortages due to a population increase and low irrigation inefficiency. Local stakeholders therefore need low-cost, easy-to-use decision-support tools to enable them to monitor and exploit the water resources to best advantage at different spatial and user levels. A top to bottom series of adapted water management tools has been successfully installed to address current problems, from watershed level (top) to individual field level (bottom), and including the 1,200 ha irrigated rice scheme. Remote sensing techniques have been developed to map the agricultural lands. Combined with data from a network of hydrologic gauging stations, regional water-use maps have been compiled. SIMIS software is being used for the public-private management of the irrigated rice scheme. A simple field-crop-water balance model, AquaCrop, is being used by extension workers to draft optimal irrigation charts. Day to day water use on irrigated plots was monitored by soil humidity and crop canopy measurements. Each water management tool is applied independently, requiring only limited data, but their combined results are contributing to improved integrated water management. [less ▲]

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See detailA public-private partnership experience in the management of an irrigation scheme using decision-support tools in Burkina Faso
Wellens, Joost ULg; Nitcheu, Martial; Traore, Farid et al

in Agricultural Water Management (2013), 116

Within the framework of a national policy on food sufficiency dating back to the late 1960s, a 1,200 ha State-run irrigated rice scheme, called the ‘Kou Valley’ scheme, was established in south-western ... [more ▼]

Within the framework of a national policy on food sufficiency dating back to the late 1960s, a 1,200 ha State-run irrigated rice scheme, called the ‘Kou Valley’ scheme, was established in south-western Burkina Faso. Jointly managed over a long period by State officials and a series of international development agencies, all aid ended abruptly in 1993, leaving the farmers and their hastily assembled Water Users Association (WUA) poorly prepared to assume management of the scheme. Concerned about the poor state of the water management and aware of their lack of management skills, the WUA turned to a private external operator for support via a public-private partnership (PPP), which involved outsourcing the water management. Initially, the PPP was funded and assisted by an international development agency. The costs are now gradually being met by the WUA and will ultimately represent 12% of the water fees collected from WUA members. An irrigation advisor was appointed on a full-time basis, and technical studies were conducted to assess the water management problems and put forward viable solutions using decision-support tools (SIMIS). At various stages, participatory meetings were organised to enable the farmers to express their opinions and to propose and discuss possible solutions. After 3 years, there was some improvement in the land occupation situation and the water distribution was more equitable in some parts, as shown by various performance indicators and a general survey. However there are limits to what water management change alone can achieve without essential infrastructural improvements. As the WUA members lacked the necessary education, effective knowledge transfer was not possible and therefore assistance on water management is likely to remain in private or State hands. The farmers, however, have indicated their satisfaction with the proposed approach and their willingness to participate in PPP-based management of the scheme. [less ▲]

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See detailImportance of a Well-distributed Frequency of Measurements in the Senescence Monitoring of Winter Wheat and Yield Estimates
Kouadio, Louis; Djaby, Bakary ULg; El Jarroudi, Moussa ULg et al

in Journal of Agricultural Science and Technology (2012), 2

Theoretical frequencies of green area index (GAI) measurements were assessed in order to bring out the optimum frequencies for the monitoring of the senescence of winter wheat as well as the relationships ... [more ▼]

Theoretical frequencies of green area index (GAI) measurements were assessed in order to bring out the optimum frequencies for the monitoring of the senescence of winter wheat as well as the relationships between metrics which could be derived and the final grain yield. Several profiles of GAI decreasing curves were elaborated based on field measurements. Two functions, usually employed in green leaf area decreasing curves fitting (i.e., modified Gompertz and logistic functions) were then used to characterize the senescence phase and to calculate their metrics. These analyses showed that the two curve fitting functions satisfactorily described the senescence phase on frequencies of four to six GAI measurements, well distributed throughout a period of 30-35 days. The regression-based modeling showed that those involving metrics from logistic function (i.e., maximum value of GAI, green area duration and senescent rate) were more suitable than that of the modified Gompertz function for wheat yield estimates. Such results could be useful for studies at larger scales (involving remote sensing airplane or satellite data) and focused on the senescence in terms of optimum number of measurements and frequencies for developing models for yield estimates. [less ▲]

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See detailTypology of the Main Fungal Diseases Affecting Winter Wheat in the Grand Duchy of Luxembourg
El Jarroudi, Moussa ULg; Kouadio, Louis; Delfosse, Philippe et al

in Journal of Agricultural Science and Technology (2012), 2

Over the 2003-2009 period, field campaigns were carried out in order to identify the main fungal diseases of winter wheat (Triticum aestivum) in the Grand-Duchy of Luxembourg. Four fungal diseases ... [more ▼]

Over the 2003-2009 period, field campaigns were carried out in order to identify the main fungal diseases of winter wheat (Triticum aestivum) in the Grand-Duchy of Luxembourg. Four fungal diseases (septoria leaf blotch (SLB), wheat leaf rust (WLR), wheat powdery mildew (WPM) and fusarium head blight (FHB)) were observed and a regional-based typology was established according to their severity and prevalence. In the Gutland (South), SLB severity was strong (about 51% on average) and higher than the severity (about 16%) prevailing in the Oesling (North). Similar typology was observed with the WLR: high severity in the Gutland (66% and 57% for the years 2003 and 2007, respectively) and low severity (< 1%) in the Oesling. The FHB was also present in the Eastern part of the Gutland, with a prevalence and severity significantly higher (P = 0.049 and P = 0.012, respectively, Tukey’s test) compared with their values in the Oesling. On the other hand, the WPM severity was high in the Oesling (15% to 40%) while less than 1% in the Gutland. Such a study is important for the spatial mapping of wheat fungal diseases risk based on agroclimatic parameters and for defining optimal frequencies and dates of chemical treatments. [less ▲]

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See detailCan satellites help organic crop certification?
Denis, Antoine ULg; Desclee, Baudouin; Migdall, Silke et al

Poster (2012, November 08)

Organic agriculture, while producing healthy food and contributing to protect the environment, needs to be certified in order to meet the consumers confidence. The objective of this study was to ... [more ▼]

Organic agriculture, while producing healthy food and contributing to protect the environment, needs to be certified in order to meet the consumers confidence. The objective of this study was to investigate how earth observation techniques could enhance the crop certification process and in particular the possibility to discriminate organic and conventional fields. These different crop management methods results in crop biophysical differences which are supposed to be observable by earth observation techniques. A set of satellites with varying spatial and spectral resolution was used to compute discriminant indicators. Under the best conditions the results show a complete discrimination between organic and conventional crops. [less ▲]

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See detailTan Spot on winter wheat in the Grand Duchy of Luxembourg: Diagnostics and Evolution
El Jarroudi, Moussa ULg; Kouadio, Louis; Beyer, Marco et al

Poster (2012, October)

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See detailWheat disease forecasting using weather radar observations
Mahtour, Abdeslam; El Jarroudi, Moussa ULg; Delobbe, Laurent et al

Poster (2012, June)

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See detailCinétique de décroissance de la surface verte et estimation du rendement du blé d’hiver
Kouadio, Amani Louis ULg; Djaby, Bakary ULg; Grégory, Duveiller et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2012), 16(2), 179-191

A large number of agrometeorological models for crop yield assessment are available with various levels of complexity and empiricism. However, the current development of models for wheat yield forecasting ... [more ▼]

A large number of agrometeorological models for crop yield assessment are available with various levels of complexity and empiricism. However, the current development of models for wheat yield forecasting does not always reflect the inclusion of the loss of valuable green area and its relation to biotic and abiotic processes in production situation. In this study the senescence phase of winter wheat (Triticum aestivum L.) is monitored through the GAI (Green Area Index), calculated from digital hemispherical photography taken over plots in Belgium, Grand-Duchy of Luxembourg and France. Two curve-fitting functions (modified Gompertz and modified logistic) are used to describe the senescence phase. Metrics derived from these functions and characterizing this phase (i.e. the maximum value of GAI, the senescence rate and the time taken to reach either 37% or 50% of the green surface in the senescent phase) are related to final grain yields. The regression-based models calculated with these metrics showed that final yield could be estimated with a coefficient of determination of 0,83 and a RMSE of 0,48 t.ha-1. Such simple models may be considered as a first yield estimates that may be performed in order to provide a better integrated yield assessment in operational systems. Indeed, estimation of cereal-crop production, particularly wheat, is considered as a priority in most crop research programs due to the relevance of food grain to world agricultural production. [less ▲]

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See detailMaladies du blé d'hiver au Luxembourg Les interactions entre climat, sol et phytotechnie montrent l'importance primordiale du facteur climat
El Jarroudi, Moussa ULg; Giraud, Frédéric; Delfosse, Philippe et al

in Phytoma : La Défense des Végétaux (2012), 650

Malgré sa petite taille, le GDL est caractérisé par deux régions très contrastées en ce qui concerne les maladies cryptogamiques du blé d’hiver. Une analyse en composante principale a permis d’analyser la ... [more ▼]

Malgré sa petite taille, le GDL est caractérisé par deux régions très contrastées en ce qui concerne les maladies cryptogamiques du blé d’hiver. Une analyse en composante principale a permis d’analyser la distribution des maladies cryptogamiques entre le Gutland et l’Oseling. La distribution des maladies cryptogamiques est significativement différente (P < 0.001) entre le Gutland et l’Oesling. Entre 2003 et 2009, la septoriose et la rouille brune sont des maladies qui caractérisent le Gutland avec respectivement comme pourcentage 51 et 17%. Dans l’Oesling, la sévérité de ces maladies était très faible et n’atteignait même pas 1%. A l’opposé, l’Oesling est caractérisée par l’installation de l’Oïdium surtout en 2003 et 2009 avec respectivement 15 et 40% de sévérité alors cette maladie ne dépassait pas 1% de sévérité en Gutland. Parallèlement à ces maladies, d’autres pathogènes fongiques sont observées uniquement en Gutland et les maladies qu’ils causent sont influencées par la phytotechnie. Il s’agit de l’helminthosporiose et de la rouille jaune avec comme caractéristique le contournement du gène de résistance Yr 17+. La variation dans l’expression des maladies cryptogamiques entre le Gutland et l’Oesling est surtout due aux différences marquées des conditions climatiques entre les deux régions mais aussi aux pratiques agricoles en vigueur (fumure azotée, choix variétal, semis avec labour ou sans labour….). [less ▲]

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See detailEstimating regional wheat yield from the shape of decreasing curves of green area index temporal profiles retrieved from MODIS data
Kouadio, Amani Louis ULg; Duveiller, Gregory; Djaby, Bakary ULg et al

in International Journal of Applied Earth Observation and Geoinformation (2012), 18

Earth observation data, owing to their synoptic, timely and repetitive coverage, have been recognized as a valuable tool for crop monitoring at different levels. At the field level, the close correlation ... [more ▼]

Earth observation data, owing to their synoptic, timely and repetitive coverage, have been recognized as a valuable tool for crop monitoring at different levels. At the field level, the close correlation between green leaf area (GLA) during maturation and grain yield in wheat revealed that the onset and rate of senescence appeared to be important factors for determining wheat grain yield. Our study sought to explore a simple approach for wheat yield forecasting at the regional level, based on metrics derived from the senescence phase of the green area index (GAI) retrieved from remote sensing data. This study took advantage of recent methodological improvements in which imagery with high revisit frequency but coarse spatial resolution can be exploited to derive crop-specific GAI time series by selecting pixels whose ground-projected instantaneous field of view is dominated by the target crop: winter wheat. A logistic function was used to characterize the GAI senescence phase and derive the metrics of this phase. Four regression-based models involving these metrics (i.e., the maximum GAI value, the senescence date and the thermal time taken to reach 50% of the green surface in the senescent phase) were related to official wheat yield data. The performances of such models at this regional scale showed that final yield could be estimated with an RMSE of 0.57 ton ha−1, representing about 7% as relative RMSE. Such an approach may be considered as a first yield estimate that could be performed in order to provide better integrated yield assessments in operational systems. [less ▲]

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