Chimney soot and newspaper could boost Kenyan crops

A low-cost sensor system to detect nutrients and improve soil fertility aims to tackle food insecurity in Kenya.

The project takes inspiration from ancient art and design-based printing processes such as wood blocking, combined with local natural materials like chimney soot, egg, newspaper and enzymes from local plants and bacteria.

The natural inks used in wood blocking will be used to make very biodegradable single use sensors, in a collaboration led by the University of Strathclyde.

The novel sensors will help farmers conduct regular tests for the two most depleted soil macro-nutrients in Kenya – nitrate and phosphate.

More than 80% of Kenya’s population is dependent upon agriculture for employment, income, or food security, but a large proportion is food insecure, with more than a quarter of children under five suffering from malnutrition, according to UNICEF.

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 land areas vulnerable to drought.

Other challenges include land conflicts and people dropping out of nomadic life to move to settled communities dependent upon food aid.

More effective agricultural productivity methods are urgently needed, such as improved soil fertility. However, most smallholders don’t know the nutrition status of their soil and how it changes in response to farming methods.

No accessible low-cost technology currently exists, and soil laboratories are too few and expensive to use in far-flung locations.

Dr Andrew Ward from Strathclyde’s Department of Civil and Environmental Engineering, explains, “This 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, we are going to borrow these 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, could we use yesterday’s newspaper, some egg yolk as a binder, carbon black from chimney soot and some plant-based proteins to produce the sensors.

“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, to provide timely information on soil fertility needs.”

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

Scientists at Kenyatta University in Nairobi and printing specialists at Glasgow School of Art will collaborate with Strathclyde to develop the sensor in the UK, with help from a Kenyan researcher.

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

Researchers say that knowledge and learning from the project could also support the manufacture of nature-based and zero waste sensors for UK agriculture in the transition to net zero.

The project is funded by the International Science Partnerships Fund, on behalf of UK Research & Innovation.

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