Web based soil maps
Web based soil maps
Demand for soil data is growing
As planners and land users increasingly recognize the crucial role of soils in food security, climate regulation and other global issues, demand for soil data is soaring. Readily available data is needed on different scales: at the global level (scale 1:5 million; 5 km resolution), regional level (scale 1:1 million; 1 km resolution), and national and local levels (scale 1:250 000 to 1: 50 000; 250 - 50m resolution). Institutes in over 100 countries have been compiling soil maps and data systems on different levels for more than a century. A key responsibility of ISRIC’s is to collect, document and preserve soil-related materials (e.g profiles, samples, reports, maps), and to harmonize these for improved databases and maps.
Towards digital soil maps
Existing soil maps and soil information systems need to be improved as many of these are not user friendly. Some are inaccessible, others incomplete or out of date, and the various data need not be comparable. What’s more, current maps only cover one-third of the earth’s ice-free land surface and do not provide uniform information. To help solve these problems, ISRIC and its partners are developing new approaches to soil mapping, with the goal of user friendly, digital soil maps for scientists, policymakers and land users
Web-based, digital soil maps are not maps in the classical sense. Essentially, they are derived from spatial databases of soil properties, for instance pH, bulk density, clay content or calcium concentration. Soil properties are compiled from measured and observed soil and landscape characteristics. These data may now be collected using proximal and remote sensing techniques or web crawling. By using geo-statistical methods, soil scientists may develop models to predict and map soil properties at increasingly detailed resolutions.
Various mapping approaches
Unlike most conventional area-class maps (based on an agreed soil classification), soil property maps quantify the associated uncertainty of a calculated soil property in an area. To compile area-class and soil property maps for the world, ISRIC collects, harmonises and analyses soil data, both legacy and new. We do this generally in the framework of large international projects, looking at possible synergies between the various mapping approaches.
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Since 1966, ISRIC has been collecting soil materials from around the world, to create and maintain a world soil reference collection. The collection, created following a request by FAO and UNESCO, comprises over 1100 physical representatives of the mapping units of the FAO-UNESCO Soil Map of the World. A selection of soil profiles, called monoliths, is on display in the World Soil Museum. The whole reference collection is documented in the ISRIC Soil Information System (ISIS). During the coming three years, ISRIC will expand the world soil reference collection with some 200 profiles.
Many national organizations collect soil and terrain data. This is done at various scales and using different mapping approaches, in accord with user requirements. As a result, there are still many geographic gaps, and the lack of worldwide standards for survey techniques and soil-sample analysis has created a range of partly incompatible data. To address this issue, the International Union of Soil Science (IUSS) started the SOTER (Soil and Terrain) program in the 1990s. ISRIC and its partners (IUSS, FAO, UNEP and national soil survey organisations) developed a uniform methodology and software tools to compile standardized, harmonized "area-class" maps and associated databases using available data sources. These standardized digital maps and databases are essentially based on the conventional mapping units (area-class) approach. The globally consistent SOTER methodology has already been used to develop soil and terrain databases at continental level (Latin America, Central and Eastern Africa, Central and Eastern Europe ) and at national level (e.g. Argentina, Tunisia, Kenya, Nepal, Jordan and China, Senegal ). ISRIC is now coordinating a methodology update through the e-SOTER project. It is the European contribution to a global soil observation system (GEOSS). Various SOTER and WISE-derived products have been included in the Harmonized World Soil Database (HWSD), a project coordinated by FAO and IIASA. New ISRIC contributions are foreseen for West Africa, within the framework of the Global Soil Partnership coordinated by FAO. These area-class products present derived property estimates for over 15 soil properties (e.g., pH, texture, cation exchange capacity, organic carbon and nitrogen, bulk density, and water holding capacity) for standardised depths. These products are widely applied in a range of environmental and agricultural studies.
In November 2008, the Bill & Melinda Gates foundation and the Alliance for a Green Revolution in Africa (AGRA) started to finance the soil mapping of Sub-Sahara Africa for an Africa Soil Information Service, freely available to scientists that model climate change, food production, carbon dynamics and the like, decision makers, land use planners and other users. Partly due to the efforts of ISRIC, the International Union of Soil Scientists (IUSS) decided to support the proposed soil mapping methodology for a new digital soil map of the world, named GlobalSoilMap.net. The GlobalSoilMap.net consortium is developing new soil property maps, at various resolutions, using advanced geo-statistical approaches that consider a range of so-called co-variates (e.g. climate, topography, land use). Unlike for area-class maps, the uncertainty associated with the derived property maps can thus be quantified. Ultimately, these soil property maps may be used in studies aimed at combatting land degradation, adaptation to and mitigation of climate, and conservation of biodiversity and other ecosystem functions. ISRIC contributes to GlobalSoilMap.net by developing and testing a range of web-based sevices, known as Global Soil Information Facility (GSIF) and collating soil-legacy data.