Scottish university leads research to develop soil-testing system from local materials

Researchers are developing an affordable sensor system aimed at detecting soil nutrients, with the goal of enhancing soil fertility to address food insecurity in Kenya.

Drawing inspiration from ancient art and design-based printing techniques like wood blocking, the project incorporates locally sourced natural materials such as chimney soot, egg, newspaper, and enzymes from indigenous plants and bacteria.

These elements are utilised to create highly affordable soil sensors.

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Under the leadership of the University of Strathclyde in Glasgow, Scotland, the collaboration with Kenyatta University aims to create a pioneering sensor that enables farmers to conduct regular testing for nitrate and phosphate, the two most crucial soil macro-nutrients often depleted in Kenyan soil.

Exhausted and nutrient poor soil is a major impediment to high crop yields, and the situation is worsened by population growth reducing the size of land parcels and farmers being pushed into drier, lower quality areas vulnerable to drought.

Other challenges include conflicts around competition for land and people leaving nomadic life to move to settled communities that are dependent on food aid.

Lead researcher Andrew Ward from the University of Strathclyde’s Department of Civil and Environmental Engineering said the project takes inspiration from woodblock printing, one of the oldest forms of printing in the world.

It uses plant-based inks to create artwork and printed information. Instead of printing art, they will borrow the techniques but combine them with functional materials, such as carbon black and enzymes to make biodegradable single-use sensors.

“We want to see if we can make a sensor using only resources that are available local to the farm. For example, we could use yesterday’s newspaper, some egg yolk as a binder, carbon black from chimney soot and some plant-based proteins to produce the sensors,” said Dr Ward.

“Ultimately, we aim to create a novel zero waste sensor for nitrate and inorganic phosphate that can be manufactured entirely in-country for easy use on farm to provide timely information on soil fertility needs.”

Researchers say that in the long term, this could be delivered to farmers as a “factory in a box” containing the tools needed for sensor manufacture, or as an information pack that shows how to gather the resources required and print sensors.

Research scientists at Kenyatta University, led by Ezekiel Njeru of the Department of Biochemistry, Microbiology and Biotechnology, and printing specialists at Glasgow School of Art, will collaborate with Strathclyde to develop the sensor in the UK.

Once a proof of concept has been created, the researchers will return to Kenya with the knowledge and understanding to recreate the sensor and test performance in greenhouse trials

“The long-term goal of the technology is to build sustained capacity in Kenya to improve soil fertility, crop yields and therefore food security,” said Dr Njeru.

The project, which is funded by the International Science Partnerships Fund (ISPF), awarded by the Engineering and Physical Sciences Research Council on behalf of UK Research and Innovation (UKRI), could also influence the wider East Africa region, with 20 million people across Kenya, Ethiopia and Somalia being food insecure and facing similar challenges.