Slash and burn farming is a form of shifting agriculture where the natural vegetation is cut down and burned as a method of clearing the land for cultivation, and then, when the plot becomes infertile, the farmer moves to a new fresh plot and does the same again. This process is repeated over and over.
Slashed and burned slope. Photo by Antony Melville 2007.
Maybe about 250 million (they are not easy to count) are forced to eke out a living like that on some of the world's poorest soils. By slashing and then burning tropical forest, these landless farmers can usually sustain themselves for only 2 consecutive years on the same patch of soil. The soil then loses its fertility and they are faced with either a daily walk of several miles to a new patch or, increasingly as the number of landless farmers grows, they may have to with uproot their families to move. Often they have to cultivate hillsides as all the land lower down is used up, and as they progress up and up they are likely to meet another farmer at the top who has similarly worked his way up from the other side.
Hillsides denuded by continuous slash and burn. Photo by FUPNAPIB 2006.
When the plots are far from the dwelling place cash crops cannot be guarded from thieves or wild animals, nor can the family help when there are young children. This too ensures the farmers remain poor.
In earlier times when the population density was less, slash and burn worked reasonably well. It was then possible to leave the plots fallow for 15 to 20 years which allowed considerable regrowth of the forest and good restoration of soil fertility. Now the plots have to be reused too soon, with increasing loss of fertility. But even when it was possible to grow enough food reasonably easily with this system the farmers still remained relatively poor.
Not only is this devastating the worlds remaining tropical forests (see "keeping carbon in the trees" and "saving the rich diverse life of the rainforests") while keeping the farmers in poverty, but it is also forcing many of them to abandon the land, and migrate to city slums in the hope of feeding their families. Life in the slums can be very hard indeed.