The future is infrared (From New Agriculturalist)
In the last four decades, more than half of the land on the plains of Lake Victoria in western
Throwing light on the problem
In desertified regions, one of the main priorities is to identify areas that are not yet extensively degraded but the first step is to determine the exact level of degradation. Until recently, analysing soil samples in the laboratory cost more than US$ 50 per sample - rendering it unavailable to farmers. Representing a major advance in field diagnostics however, new infra-red technology (IR) offers a low cost and accurate method of quality diagnosis. The process, known as infra-red spectroscopy, works by shining light on a soil sample. The reflections from a range of wavelengths are collected to create a 'digital scan', which is used to determine soil composition and type.
The technology, extensively used in the pharmaceutical industry to ensure quality control in medicines, offers rapid and non-destructive soil analysis. It is able to predict potential shifting points in the soil, allowing restoration before the soil structure is entirely degraded. For example, soils susceptible to physical degradation start to degrade once a critical amount of vegetation cover has been removed. Soil erosion then sets in and finer particles such as silt, clay and organic matter are washed away and the physical structure of the soil starts to breakdown. The system therefore reaches a point where the soil structure suddenly collapses and soil nutrients are depleted.
With IR technolody, ecologist
The scanner powered by electricity costs US$75,000 but can cost-effectively analyse samples at less than a dollar per sample. Awiti reports that farmers have responded to the technology trials with "enormous excitement". However, infra-red spectroscopy is only one of many interventions introduced by ICRAF to prevent land degradation. Tree planting and sustainable agriculture are also promoted. One tree in particular - 'the tree of life' has proved considerable success. A popular leguminous tree, Gliricidia sepium, produces leaves containing 3-4 per cent nitrogen. By capturing nitrogen from the air, the plant is capable of producing nitrogen-rich bio-mass that can double or even triple maize yields. (See Agroforestry comes of age in
ICRAF also advises on reintroducing high value trees such as baobab or sheanut, and other fruit trees which provide an important source of nutrition. These trees are particularly valued in areas such as the parkland systems of
Prevention is better than cure
The IR technology is currently being used as part of the UN Millennium Villages Project, and a World Bank initiative to halt desertification. But as Awiti explains, a major consideration will be capacity building, and how to "help extension workers come on board with these technologies." The best way, he says, is to plan ahead and involve communities. Reversing desertification is a difficult and expensive process, and prevention will be much more effective, not to mention cheaper, than cure. The process will need to be sustainable in the long term, as well as effective in the short term. Soil mapping for
For further information see World Agroforestry Centre - http://www.worldagroforestry.org/