Use of modern geo-positioning devices in agricultural censuses and surveys

In the framework of the project GCP/INT/903/FRA, the Statistics Division of FAO conducted pilot surveys in Cameroon, Niger, Madagascar and Senegal to assess if a standard GPS (about 250 USD) can be used for measuring areas on the ground. The basic idea is that the use of a GPS allows reducing considerably the time needed for measuring the area of plots with the traditional method based on meter and compass; thus, area measurements made with GPS are less expensive. Moreover, if the digitized borders of the plots can be stored on a laptop, they can be a layers in a GIS and can be used for several agricultural and agro-environmental purposes. This paper presents the results of empirical studies and detailed statistical analysis conducted for assessing under what conditions GPS devises can produce accurate measures of crop areas and what are the operational issues for their use in a country-wide surve