Most people don’t think much about soils, but soils are important in many ways. Soils provide many ecosystem services including water storage and run-off prevention immediately after a rain, nutrients for plants, pollution filtration, and carbon storage.

Agriculture depends on soil to produce food, feed, fiber, and fuel. Recent advances in procedures for making soil maps and in soil data visualization are making it possible to deliver soil information directly to farmers in the field via mobile electronic devices.

Soil is Diverse and Dynamic

It’s easy to think that all soils are about the same since most soil differences occur below ground. Soils, however, can differ greatly in their native fertility, their pH (whether they are acid or basic), and their capacity to hold water for plants. Soils can have other limiting conditions such as steep slopes, shallow rooting depth, acid subsoils that make it difficult for roots to take up water and nutrients, or wet, waterlogged conditions that impede root growth for most crops.

Knowing the description of a soil is especially important for farmers as they depend on soil for their livelihood. By understanding the description of a soil, farmers can better choose crops to grow and the limitations that the soil might create. Understanding soil is integral to global food security.

Making Soil Maps Available

So how do you learn about soils and how their properties vary in different areas? One way is to study soil maps. If good soil maps are available, you can obtain information about soil properties without physically visiting an area yourself.

There are not as many soil maps available for Africa as for some other parts of the world, but the situation has gotten significantly better over the last decade. The Soil Atlas of Africa published by the European Soil Data Center provides a continent-wide overview of soil resources and highlights the tremendous diversity of soils on the continent. Africa Soil Information Service(AfSIS) and ISRIC World Soil Information have released SoilGrids, a series of digital soil property maps for the entire world, including Africa, at 250-meter resolution.

These maps are suitable for regional planning and modeling. Most recently, Innovative Solutions for Decision Africa(iSDA) has released soil property maps for Africa at 30-meter resolution. These are the highest resolution data currently available and will be useful for local planning. Both the AfSIS/ISRIC and iSDA data products were produced with state-of-the-art predictive soil mapping approaches.

Digitalizing Soil Maps

Maps are of little use if they are not easily accessible. Much of Purdue’s work has focused on the visualization and delivery of soil information. Soil Explorer, a soil map delivery tool developed at Purdue University, is available as a free mobile app for iPhone/iPad and Android devices, and as a web page. The primary focus has been visualization of soils data from the US but has also added maps for other countries like Kenya and Peru.

Purdue has successfully tested Soil Explorer as a delivery tool for these digitized soil maps in rural western Kenya. To develop soil maps for western Kenya, researchers were able to update previously published soil maps. For the soil survey of the Busia area, Purdue was pleasantly surprised that the survey contained detailed procedures for developing crop suitability maps.

This suggests that existing soil maps lying idle in libraries can be put back to use without the expense of remapping the soils of the area.

These are exciting times in soil science. As new soil property maps become available from state-of-the-art digital soil mapping approaches, Internet-based delivery of both new and existing soil maps makes it practical to provide soil information to the farmers that rely on this information.