The African Soil Information System (AfSIS) is developing a map to show soil conditions across the continent. The service will help to identify the risk of soil degradation, how to prevent it and how to restore land where soil fertility is already depleted. AfSIS takes advantage of recent advances in digital soil mapping, remote sensing, statistics and soil fertility management to analyze the various alternatives to protect and rehabilitate soil. The project is also testing a variety of farming techniques in an effort to discover the most effective methods to suit a wide range of conditions and situations.
The soil map will be available for free on the internet, and continually updated. The high resolution of the map means that farmers will have the possibility to zoom in to see the condition of the soil on their land. The project team are also looking at other ways to make the data available, via mobile phones, for example. Farmers and extension services would be able to directly access specific information for their location, and use the proven methods to develop the land and improve harvests in that area.
The project, led by the International Center for Tropical Agriculture (CIAT) in Nairobi, Kenya, is collecting data that will also address issues of food security, environmental degradation, and climate change in sub-Saharan Africa.
There is very little existing soil data for sub-Saharan Africa. Few results from previous soil surveys came with sufficient location information. Also, the testing methods varied greatly, and the interpretation of the results was not always reliable, making it difficult to compare the data from the different sources. One objective of the AfSIS research, therefore, is to develop a baseline – an overview against which future results can be compared – using standardized tests and procedures. By applying an agreed process of sampling and analysis, the scientists will be able to build up a comprehensive picture of soil health and degradation in an area of sub-Saharan Africa covering 42 countries and more than 18 million square km.
Part of this testing procedure is to take physical samples of soil from selected sites. AfSIS has identified 60 locations, known as sentinel sites, each 100 square km in size. Three sub-regional field offices are responsible for coordinating the collection of samples. The Agricultural Research Institute in Arusha, Tanzania, is responsible for the survey sites in East Africa, the Agricultural Research Service in Lilongwe, Malawi, covers Southern Africa, while samples in West Africa are handled by the Institut d’Economie Rural in Bamako, Mali. Each organization will establish a regional soil testing laboratory with the necessary equipment and an internet connection to link all the centres.
Sending field workers to remote, randomly chosen locations to scoop samples of soil is very time-consuming. AfSIS expects that, in the four-year term of the project, each regional centre will concentrate on five sentinel sites per year, spending an average of two months to collect 32 soil samples from each location. The laboratories will then analyze the samples using infra-red spectroscopy and x-ray diffraction to determine the soil composition.
The field workers use handheld PDA devices fitted with GPS receivers to document the exact location of where the soil sample was taken. The field workers can store a backup of the data on external hard drives while still at the site, and then transmit the information to the main data repositories at the World Agroforestry Centre and the Tropical Soil Biology and Fertility Institute, both based in Nairobi, Kenya.
The results of the studies, coupled with their respective location coordinates, are added to the soil map. The map can then provide information on the properties of different soil types across the continent, including details on the water filtration rates and capacity of the soil to produce crops and store essential nutrients. It will show the prevalence of minerals that can limit crop productivity, such as high levels of aluminium or low carbon concentrations, and give recommendations on improving soil fertility depending on location.
Remote sensing technology and the analysis of high-resolution satellite imagery provide further details on soil moisture, nutrients and organic content. This information also gives a broader overview of soil properties in places that have not been sampled. The project team can use the extra data to predict with great accuracy the condition of soil over large areas. The map can show the properties of soil throughout the continent in blocks representing areas of land measuring 90 x 90 metres. This gives the map a resolution 100 times greater than any previous soil map.
The AfSIS team expects that their data will also be used to develop national and international policies for improving soil quality. Governments and agricultural research centres will be able to use the information to provide targeted soil management programmes which would, for example, organize the supply and assess potential uses of fertilizers.
The main beneficiaries in the initial research stages of the AfSIS project, however, are likely to be the national soil and agricultural laboratories, and African universities. Many of these institutions have been underfunded in recent years, while admissions to soil science courses in African universities have fallen dramatically, even at the undergraduate level. AfSIS will provide many opportunities for field training at the sentinel sites and other soil management locations, and will supervise a number of postgraduate students at several African universities.
The project will fill the current gap in soil information to help farmers maximize the use of their land, and to assist agronomists and extension agents to plan and develop methods for improving soil fertility. Information gathered by AfSIS will also be used in a wider international effort to produce a digital map of the world’s soil resources as part of the Global Digital Soil Properties Map initiative. Scientists from soil information and agricultural development institutes in Mexico, Canada and the US are cooperating with the AfSIS team to produce the global map.
The soil map website and systems to deliver the information to mobile phones will ensure that the data collected can reach the complete spectrum of people involved in farming in Africa. National agricultural research centres will continue to collect and add new data, public and private extension services will customize their training programmes, and national and local government departments can adopt appropriate policies to assist rural communities. All of which will combine to give small-scale farmers broad support and access to detailed advice on how to improve their crop productivity and profits.