Farming from the ground up

Scientists use the latest technology to produce a digital soil map of Africa

Agricultural researchers throughout Africa are using the latest technology to develop a digital map showing the properties of soil across the continent. Farmers will be able to get detailed information on soil fertility in their area.

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 rapid developments in geographic technology make this type of research more cost-effective than previously. Coupled with the spread of mobile phones and internet access, the service can easily get the information they gather to those who need it most, including small-scale farmers in remote areas.

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.

At the launch of the service in January 2009, Kofi Annan, former UN Secretary-General and chairman of the funding organization, Alliance for a Green Revolution in Africa, said, ‘The best science and technology available must be deployed immediately if Africa’s soils are to be managed in a sustainable manner. AfSIS is a most welcome addition to the arsenal of tools deployed against the scourge of hunger in Africa.’

Setting standards

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.

Working with local farmers, researchers also use the sentinel sites to test a variety of farming methods, such as erosion control, conservation tillage and agroforestry techniques on different types of soil and landscapes. The tests will not only prove useful when the service starts giving advice to farmers, but will also help to develop and standardize the testing procedures for future tests at more locations.

One important part of the project investigates methods farmers can use to improve the fertility of their soil. The trials compare the effectiveness of different fertilizers used on a range of soils, the rate of fertilizer application and the integration of legume crops in crop rotation systems.

Farmers in Africa typically use very little fertilizer compared with farmers in the rest of the world. Meanwhile, soil quality is rapidly decreasing due to increased pressure on the land from repeated droughts, flooding, overgrazing and demands from a growing population.

Through its wide range of studies, AfSIS is compiling information that the service can later use to advise farmers with very specific details on how to improve the fertility of their soil and the productivity of their crops. AfSIS recognizes, however, that to be truly effective they will have to deliver a complete range of information services to farmers, including advice on market data, credit management, technology and climate change. Team members are, therefore, also collating details on these subjects.

Broad audience

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 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 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 benefi

ciaries 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 innovative use of technology and the development of standardized scientific soil sampling methods will make AfSIS a cost-effective and efficient surveillance service to map soil conditions. Its work will set a baseline for monitoring changes, and provide options for improved soil and land management.

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.

AfSIS innovations

AfSIS innovations

In the process of producing a soil map of Africa, the AfSIS team have introduced a number of new standards and techniques that are likely to affect the broader sector of soil science. The project will lead to the development of:

  • international evaluation standards that will be consistently applied in soil collection and analyses to determine soil degradation and recovery processes, the nutrient supplying capacity, water holding capacity, carbon density and other functional properties of soil
  • mechanisms to statistically analyze results and translate them into recommendations for soil management techniques
  • a database of soil management trials in sub-Saharan Africa
  • monitoring and evaluation procedures to track progress of the project allow users to give feedback and to continue testing the recommended soil management techniques
  • methods to effectively communicate the information gathered, such as websites, printed manuals and guidelines, policy briefings and a digital atlas
  • a communication network to coordinate data collection and analysis.
  • The project is also gathering research and data from around the world to compile the first comprehensive database of soil information. AfSIS will:
  • acquire and analyze data from previous soil surveys
  • gather data on rainfall, vegetation and other environmental factors affecting soil in sub-Saharan Africa
  • link soil management information gathered from the project research and other studies to the digital soil map to make the information easier to access
  • collect information on proven soil management techniques, together with the necessary location information, from national research institutions and extension services in the countries involved
  • introduce the soil health information system into the national institutions to ensure that the maintenance and updating of the service continues beyond the initial four-year term of the project in 2013
  • provide training to African soil scientists in the new techniques and standards.


Related links

African Soil Information Service
The main AfSIS website with further information on the methods used, details of the sentinel sites and field trials.
Global Digital Soil Properties Map
An international consortium of organizations cooperating to develop a global soil map.
Alliance for a Green Revolution in Africa
AGRA supports small-scale farmers in Africa by improving access to markets, information, financing, storage and transport.
International Center for Tropical Agriculture (CIAT)
CIAT promotes research into efficient agricultural techniques.
Tropical Soil Biology and Fertility Institute
TSBF promotes the health and fertility of soil for agriculture in tropical ecosystems.
ISRIC - World Soil Information
An independent organization and partner in the development of the global soil map.

29 April 2010

Copyright © 2016, CTA. Technical Centre for Agricultural and Rural Cooperation (ACP-EU)