SoilCards

Soil-nutrient testing for every farmer

SoilCards are paper tests that make soil-nutrient analysis easy, quick, and affordable to smallholder farmers who don’t have access to soil-testing laboratories.

Farmers need to measure soil health to manage it

There are 1.4 billion farmers who live below the poverty line, most of whom can't access or afford soil testing in laboratories. Without a way to measure the concentration of nutrients like Nitrogen (N), Phosphorous (P), Potassium (K), and pH in their soil, they can't make informed decisions about which fertiliser to use, how much to use, and where to use it. Farmers can't afford to use expensive fertilisers inefficiently, and excess fertiliser run-off use has serious environmental consequences.

SoilCards make soil testing accessible to every farmer

SoilCards present a soil-nutrient profile to farmers so that they know exactly which fertiliser they need. With proper fertiliser use, farmers can double or triple their yield, improving their socio-economic status while protecting the environment. SoilCards are made of paper so they are small, light and inexpensive, so they can be distributed to even the poorest farmers in the most remote locations, to test soil without technical staff or any special equipment and infrastructure.

Automated chemistry and an easy-to-read display

Colour-changing chemical tests can be portable and provide a way to measure nutrient concentration without electricity, but they are complicated to use, and difficult to read by eye and interpret. SoilCards use paper microfluidics technology to automate the steps involved in a chemical test. They are also easy to read like a pregnancy test because they use an innovative display of discrete spots instead of a change in colour hue or intensity.

Soilcards are simple paper cards that open and close like a book. On the inside, you add some of the soil you want to test to the sticky soil pad, and then fold the SoilCard closed. Then you add water to the water pad, and rub your thumb on the mixing pad to rinse the nutrients out of the soil.

This water carrying dissolved nutrients flows through the microfluidic channels in the analysis panel, resulting in a chemical reaction which makes spots on the display panel appear. After a few minutes you can count the number of spots which indicate nutrient levels in your soil. Now you can compare your soil nutrients to the optimal levels for your desired crop, which are shown on a reference card.

Our progress:

We explored the challenges of soil testing with the UK farming community.
We used our method for rapidly prototyping microfluidic diagnostics to design a soil test that is suitable for even the most resource-limited settings.
In the labs at Imperial College we have created a paper microfluidic SoilCards prototype which tests soil Nitrogen. We have developed a novel, discrete display to convey nutrient concentration, using robust chemistry which is suitable for long storage times and potentially hot environments.
In mid-2017 we will begin user-research in Kenya, supported by an award from the Cambridge-Africa ALBORADA Research Fund .

We're seeking funding for:

Further technical development to turn our prototype into a product.
Further fieldwork to gather feedback from farmers and understand the context that SoilCards will be used in.
Exploring the best way to make SoilCards results actionable for farmers.

Long-term plans for SoilCards:

We would like to develop SoilCards into a social enterprise with the broadest possible social impact.

SoilCards is a Science Practice project in collaboration with Imperial College London, the UK’s National Institute of Agricultural Botany (NIAB) and the Kenya Agricultural and Livestock Research Organization (KALRO). Science Practice is a design and research company in London working at the intersection between science and design.