In a precision farming research project financed by the Belgian Ministry of Small Trade and Agriculture, the methods of precision agriculture are tested on grain fields with a view of implementation of precision agriculture methods in Belgian field agriculture. The project encompasses methods for automatic information gathering on soil and crop and analysis of this data for management of within-field variability. Automatic information capturing is combined with traditional data sources of soil sample analysis and crop observations. The measurements and part of the results on one particular field in Sauveni" e ere are presented here. Five nitrogen management strategies were compared, but the resulting differences in nitrogen dose were small and did not lead to significantly different yield results. The yield results were correlated to topography-related variations in soil texture and chemical components and to crop reflectance measurements in May.

No abstract

No abstract

No abstract

For hydrology and terrestrial ecosystem studies, topography has a significant influence on the amount of intercepted solar radiation, the surface and sub-surface water movements, the type and distribution of vegetation and the microclimate. Processing Digital Elevation Model (DEM) data to extract hydrological features becomes a routine, but the numerous DEMs available stress the importance of their quality assessment. Radar interferometry (InSAR) technique is a promising approach to generate digital elevation models. The goal of this research is to verify to what extend the InSAR DEM can be used as a topographic database for deriving hydrological informations. This study was realised over the Dendre and the Lesse watersheds. Because DEM quality cannot be determined by a single criterion, the quality assessment should be application oriented. In this study, the NGI (National Geographic Institute of Belgium) DEM was chosen as a topographic reference for the quality assessment of the InSAR DEMs. The Root Mean Square (RMS) of the altitude difference between the NGI and the InSAR DEM was used as general quality measurement. The mean slope value has been calculated to characterise the relief of the basin. For both of the basins, watershed borders and hydrographic network were generated with GIS technique. The results obtained were compared between them and with digitised hydrographic network. Hydrographic network derived from InSAR DEM was not found accurate enough in flat wide valley. For the studied areas, the InSAR DEMs are precise enough for large-scale hydrological investigation where information like watershed border or relief is needed. However, InSAR DEMs is not suitable for hydraulic models, because they require extreme accuracy.