| Agricultural extension |
|Providing agricultural support services|
Surveying as it is meant here is the branch of applied mathematics used to determine the area of any portion of land, the lengths and directions of boundary lines, the elevation and contour of the surface and the art of accurately delineating these measurements on paper. Surveying of this kind is a service provided rarely to small-scale farmers. It is important to them for several reasons:
• As land tenure and farm practices allow for more individual ownership or tenancy of land, it is important to know the exact location, boundaries and area of a parcel of land.
• This is doubly true where there is a shortage of land.
• In order to calculate optimum seed, lime, manure, fertilizer, irrigation or other applications on a given extent of land, precise area measurements are necessary.
• In order to properly level or contour a field to use irrigation or rainfall water most efficiently, the elevation and contours must be measured exactly and mapped out.
• In order to locate irrigation channels, dikes or drains, contours and elevation must be accurately gauged.
Surveying is done on two planes: boundaries and area measurement are located on a two dimensional plane - length and width; elevation and contours are located on a three dimensional plane - length, width, and height. Boundaries and area measurements are depicted on a map as lines. Elevations and contours are indicated by points or lines marked with a certain height value, (see ILLUSTRATION).
This kind of multi-dimensional "literacy" is not often easy to share with village farmers, who have learned a different type of spatial orientation. See Chapter Four, FARMER TRAINING, "Cross-Cultural Communication", for an indication as to the nature of visual and spatial "illiteracy" and how to cope with it.
Map and contour survey of Pa Jo's farm (rice paddy & vegetables).
ICE by-request-only reprint.
Sierra Leone Surveying Manual