What is Desertification?

Desertification is the degradation of land in arid, semi-arid and sub humid zones of the world, leading to the loss of the capacity of land to support life. It is not necessarily the encroachment of sand dunes, observed in the fringes of the deserts.

How severe is Desertification?

Desertification threatens over one billion people worldwide - one-fifth of the entire population of the Earth.

• Over 135 million may be in danger of being driven from their land as it becomes desert.
• Two out of every three countries in the world are affected by desertification.
• Desertification damages almost one-third (30 percent) of the total land area of the world.
• About 73 percent of Africa’s drylands are moderately or severely affected by desertification.
• Desertification costs the world an estimated USD 42 billion a year.

What causes Desertification?

In addition to climate variations, four human activities are usually the most immediate causes of desertification:

• Overcultivation exhausts the soil.
• Overgrazing removes the covering of vegetation that protects it from erosion.
• Deforestation cuts the trees that bind the soil to the land.
• Poorly drained irrigation turns cropland salty, desertifying 500 000 hectares each year.

In the past, the people of the drylands were blamed for destroying their own livelihoods. But as the Convention recognizes, there are usually deeper underlying causes that leave them no alternative: the principal cause being poverty. Poverty drives the poor to obtain as much out of the land as possible to feed their families in the short-term, even though they are thereby foreclosing their long-term futures.

30% of the Earth’s land surface is affected by the degradation of fragile drylands

Some Indigenous Technologies for Soil and Water Conservation

Contour Stone Bunds

Contour stone bunds are small stone structures (usually 25-30 cm high) built along contours with the help of a simple device. They help avoid erosion and recharge the soil’s water supply. They work in the following way:

• Medium-size stones are placed vertically within a foundation trench. Smaller stones are placed around the area to help brace the structure and assist in filtering run-off water.
• As water runs down the incline, it is delayed by the stones blocking its path. The semi-permeable structure allows the excess water to pass through.
• The run-off water, which would have otherwise caused erosion, sinks into the ground, providing the crop with extra moisture and replenishing the water table.
• Silt and organic matter are also trapped in the process, building up soil fertility.

Half-Moons

A process called "half-moons" allows the texture of the land to capture water as it flows. Here is how it helps save water and feed livestock:

• An A-frame device is used to sketch circles in a field.
• Half-moon-shaped holes are dug in a pattern across the field.
• Run-off water fills the holes and creates water build-up in the soil.
• Fertile soil, mixed with water, produces a grass that feeds livestock and helps fight erosion.

The Caag System

The Caag system catches water run-off and then diverts it to carefully designed "earth bunds", thus ensuring a sufficient supply of water for crops.

Contour Stone Bunds With Planting Pits

Tassa (planting pits) are carefully dug and fertilizer, manure and seed are deposited in them. They then retain water channalled in through the use of stone bunds.

Indigenous Technologies from West Asia

"Underground" agriculture in the rural areas of Bushire, the Islamic Republic of Iran, is a way of using extremely scarce run-off water in underground cisterns, where figs, vines and date palms are planted that give a very high yield. There is evidence that this technology dates back to the Ilamite period, some 4 000 years ago.

Rangeland rehabilitation in Lorestan (Iran) is carried out by nomadic pastoral women. They collect seeds of palatable range species with which they stuff pierced goatskins. The seeds are slowly released from the goatskins as they are dragged along by the lead goats in the flocks. The sheep following the goats then trample the seeds into the soil and fertilize them. As the sheep flock moves around the rangelands, they also fertilize the soil sheep goat manure. When the rains arrive, the rangelands are rapidly rehabilitated with native species of forage.

The Future of Alley Farming Brightens

IFAD is supporting an IITA-led research network of 23 sub-Saharan African (SSA) countries that has developed and is promoting alley farming as a production alternative to slash-and-burn shifting cultivation. By reducing the amount of land needed to be cleared for farming, alley farming saves tropical rainforests.

The system involves the cultivation of food crops in alleys between hedgerows of multipurpose trees or shrubs, usually legumes. The legumes have deep roots and help in nutrient cycling and fixing of nitrogen; their nitrogen-rich leaves can be used as green manure for soil fertility and as fodder for livestock. The wood provides fuel and staking material for yams and other climbing crops.

With these acknowledged advantages, much enthusiasm has been generated for this technology. However IFAD-financed research has shown that it is a niche technology and not a panacea for the whole of SSA. Although widespread adoption has not ocurred, alley farming remains the most promising technology yet developed for stabilizing agriculture in the humid lowland tropics and possibly in other zones.

Evidence from studies shows that earlier skepticism regarding the adoption potential of the technology appears unjustified. Farmers are adopting the technology in villages characterized by high land-use pressure, soil-fertility decline, erosion problems, and fuelwood and fodder scarcity.

In Nigeria, of the 223 farmers surveyed, 208 (93%) had heard of the technology and 66% had either initially adopted or experimented with it. Although some of the initial adopters abandoned it, nonetheless, 53% of the farmers continue to use it. In both Cameroon and Benin, 93% continue. Furthermore, the technology is catching on in the east coastal areas of Kenya and in Uganda, particularly in sloping areas, revealing a great potential for adoption throughout the highlands of east Africa.

As farmers look for a better match of technology to their resources and preferences, they are making modifications to alley farming in adopting it. The most significant modification is the use of fallow phases. For example in Nigeria, of those who alley farm, 83% add a fallow phase to suit the intensity of their cropping systems.

Resolving the constraints on alley-farming technology requires that researchers focus on technology modifications that will make the technology more flexible and adaptable to farmers’ preferences. This is the bottom line. As researchers recognize and integrate these farmer modifications into designs, adoption is increasing. Such modified alley-farming systems would need to be targeted at areas where incentives for land-use changes exist or are likely to occur in the near future, i.e., land-use pressure, soil-fertility decline, erosion and fuelwood scarcity.