1. General considerations

From very ancient times people had to be permanently concerned with providing the fundamental surviving conditions, respectively getting drinkable water and food daily. Meeting such conditions required adaptation of the following activities:

Getting potable water: People’s settlement either near rivers of permanent water or in areas with natural springs or not so deep aquifer layers
Getting daily food: Hunting, Shepherding, Agriculture

If getting potable water required conditions depending on the natural features of the respective region, with only sometimes short drainage channels or wells to be made, however in order to get food people had to also carry out some specific activities such as:

For hunting
· Chasing the game and its periodical migration, thus hunters had to be nomads
· Hunting is an activity requiring certain skills, as it might endanger the hunters’ life
· Victuals obtained by hunting could not be preserved so they had to be consumed in a short while

For shepherding (only when household grazing herbivores have been domesticated)
· Providing periodically new pastures by burning or tree cutting into shrubs or forests, shepherds being obliged to be nomads or semi-nomads, like the hunters
· Supervising the grazing cattle and guarding them during nighttimes, using enclosures against predators

For agriculture
· Fallowing the fields, planting and gathering the crops; people became sedentary while waiting for the crops to mature
· Rich crops of good years allowed gathering goods and developing trade

Statistic data show that the following land areas have to be available with a view to satisfy the food needs by capita:
- For hunting: about 100 ha / inhabitant
- For shepherding: about 10 ha / inhabitant
- For agriculture: about 1 ha / inhabitant

It thus follows that, from all activities able to provide food to the respective populations, agriculture required the lowest areas of available land. The idea is confirmed, since all peoples have developed to welfare only when they have started practicing agriculture. People’s richness relies in the first place on the gathering resulted from the cultivation of land. At present agriculture is increasingly intensive, constituting a basic activity in all countries of the world.
Since however the lands usable for agriculture are often limited by natural conditions, unproductive soils, deserts, marshy areas or cold climates that do not allow crops to mature, but also because of fast demographic growth, the possibility to acquire the daily bread becomes an ever worrisome issue. Under such circumstances it is of utmost importance to put to use the currently unproductive lands and to protect agriculture-favourable areas by maintaining and fertilising them.

The purpose of this study is to specify the solution required in order to recover the unproductive land areas in the region of Sahara- the greatest desert of the world, which impacts to a great extent the progress of central African countries, and to return them into the agricultural circuit.