Infrared scanners offer affordable soil health checks

Soil samples ready for scanning Copyright: ICRAF / Keith Shepherd

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[NAIROBI] Researchers have described how a piece of laboratory equipment ordinarily used to test the composition of drugs could transform knowledge of African soils and help poor farmers manage their land.

The infrared scanner is faster, more reliable and cheaper than conventional ways of analysing soil, said Keith Shepherd, chief soil scientist at the World Agroforestry Centre (ICRAF).

Shepherd was speaking at a press conference held in Nairobi on Tuesday (13 June) to showcase the technology.

The scanner illuminates a soil sample with infrared light, then compares the different wavelengths of light reflected back to those from soils of known composition and structure.

This allows researchers to diagnose problems such as low carbon content or susceptibility to erosion. They can then advise farmers on the best way to treat unhealthy soil, for example by applying specific fertilisers.

The scanner can also analyse the nutrient content of crops and animal feeds. It can even be used to assess the health of livestock, by analysing samples of faeces.

The scanner itself costs US$75,000, after which analysing samples costs US$0.50 each, compared with US$50 using standard laboratory tests that require costly chemicals.

Each scanner is able to analyse 400 samples in a day.

According to Alex Awiti, a landscape biogeochemist at ICRAF, farmers in Kenya responded to trials of the technology with “enormous excitement”. 

Farmers want to bolster their traditional knowledge about soil health with scientific information, he said. “They are demanding precision; they are demanding a scientific validation of their intuition.”

Shepherd expects that within ten years most African countries will be using the machines. He told SciDev.Net that the method could, for a modest investment, be used to produce a detailed map of soil health for the entire continent, something unthinkable until now.

A researcher reads the results of a soil sample test