The present document, the fifth in the series, examines the use of radiometers in the estimation of primary production in sahelian pastures, based an the Project's results. It starts with a discussion of the principles and uses of the radiometer and a description of various types of radiometer. The data collected using a hand-held radiometer are treated in detail, and the efficiency of various indices examined in order to find one that is satisfactory for the estimation of green biomass in sahelian pastures. The report presents and discusses calibrated maps of green biomass production for five years, derived from satellite images of the Ferlo which were constructed from data collected by the Advanced Very High Resolution Radiometer carried on National Oceanographic and Atmospheric Administration satellites. The airborne instrument, for which no usable data emerged from the Project's activities, is given brief mention. A glossary of terms connected to remote sensing and image processing and a list of acronyms and abbreviations commonly found in remote sensing literature are presented in annex.