Power in their hands – helping farmers to map soil health

A project supported by the SFN aims to empower smallholder farmers in India to become citizen scientists and champions for healthy soils, using a simple tool developed for mobile phones.

​‘Across the world, it is the millions of smallholder farmers who are the ones working the soil. Unless we involve them and develop tools that they can easily understand and use, we won’t be able to help soils recover.’ Rajneesh Dwevedi.
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​When it comes to food security, the focus tends to be on what is happening above ground rather than below our feet. But this needs to change – and fast. Worldwide, a third of agricultural soils are thought to be moderately to highly degraded (FAO), limiting their productivity. Besides putting millions of livelihoods at risk, global soil degradation also has significant impacts on climate change by releasing vast quantities of carbon to the atmosphere.

A key characteristic of healthy soils is that they are highly biodiverse: teeming with life that ranges from microscopic organisms, invertebrates such as nematodes, insect larvae and earthworms, and mammals, reptiles, and amphibians. All of these play a fundamental role in maintaining the benefits of soils that we depend on. For instance, as part of their metabolism many microorganisms transform essential organic and inorganic compounds into forms that plants can use. Larger species, meanwhile, such as earthworms, ants and termites, engineer soil structure through their movements and open up pores for water and gas to flow.

But modern intensive farming methods can have devastating impacts on soil biodiversity. Widespread use of pesticides and fertilizers, compaction from heavy farm machinery, and disruption to soil structure from ploughing devastate the complex webs of life below ground. This results in less efficient nutrient cycling, poorer soil structure and ultimately smaller harvests. It is a vicious cycle: as soil biodiversity decreases, agricultural productivity decreases – causing farmers to resort to even more intensive farming to try and maintain yields.

In contrast, lower impact and regenerative farming methods – such as organic farming and ‘no-till’ farming – can maintain and even restore soil biodiversity. Wider adoption of these could help us start to reverse the perilous conditions of our soils, but a major barrier to this is a lack of ready tools and technologies to easily measure soil health. ‘Maintaining soil ecosystem services is a key challenge for sustainable food production, and one that depends on soil biodiversity’ says Mr Rajneesh Dwevedi (Lady Irwin College, Delhi). 'Achieving this will ultimately depend on the knowledge and actions of farmers. Though farmers often understand the importance of soil health, they are not able to monitor and infer the ecosystem condition accurately.’

As part of a SFN-backed collaboration with the STFC, Rajneesh is addressing this by developing an easy to use, intuitive tool for assessing soil health, designed to be suitable for farmers worldwide regardless of their level of education. To start with, he is focusing on India, where a large proportion of soils (particularly in the Gangetic plains) are severely degraded. Since the presence or absence of certain organisms can be a direct indicator of soil health, Rajneesh’s specific aim is to develop an accessible tool that can quickly identify soil species. Currently, existing guides for assessing soil biodiversity are often highly technical keys and charts, requiring expert knowledge to decipher. But Rajneesh’s vision is for a mobile phone application that uses the power of artificial intelligence to accurately identify soil species from photographs taken by the user.

Having no previous experience of machine-learning approaches before, Rajneesh is working with Dr Melina Zempila from STFC RAL Space to refine the identification algorithms specific for soil organisms that will form the basis of the tool. In particular, Melina’s expert knowledge is helping to refine the method of classification using advanced image analysis based on information from the visible spectrum of light.

But to train a program, you first need a labelled dataset it can learn from. Consequently, the first stage of the project saw Rajneesh travelling across North India between March and August 2022, collecting more than sixty soil samples from as many different farms as possible. This included both farms using intensive, pesticide and fertilizer-heavy practices and those based on organic methods. ‘It was a fascinating new experience to closely study so many different soils across India and to see how the biodiversity varied’ says Rajneesh.

Back in the laboratory at Lady Irwin College, each sample was carefully analyzed and high- resolution images taken of the species to curate a database of labelled images. ‘Not surprisingly, our preliminarily observations found that soil biodiversity can vary significantly with soil type, with organic farms being richer than the conventional farms’ Rajneesh says.

In July, Rajneesh visited the STFC RAL Space facility, based at Harwell, Oxfordshire, to meet Melina and discuss the next stage of the project: developing the identification algorithms. ‘It was a great experience to see the computing capabilities at STFC, and discuss the next stages of the project together. The initial results so far have been promising, with our prototype model being effective in identifying soil fauna present on the soil surface. Below ground species, however, remain difficult as they look similar in the visible spectrum.’

Another challenge will be to tweak the algorithms so they still work effectively on simpler, mobile-phone images rather than the high resolution photographs. ‘As a first goal, we hope this tool will enable farmers to become citizen scientists, capable of mapping soil biodiversity and collecting information simply by taking a photograph. A longer-term aim is that this information can then be used policy makers to identify priority areas for restoration. It could also help farmers to select the best crops for their fields, based on the soil health’ says Rajneesh. If successful in India, the method could be adapted to the soils of countries worldwide.

Reflecting on his involvement so far, Rajneesh says: ‘I’ve really enjoyed working on this, particularly as it has motivated me to learn new things. My background is in biology, so artificial intelligence was completely foreign to me. Even so, I’ve found it a magical experience to get deep into the mathematics behind it. The SFN serves a great purpose in bringing people with different expertise together, to apply science and technology into making new solutions that ultimately help people.’

‘People often assume that grater agricultural productivity always comes at the expense of nature, but I hope we can help show that these do not have to be mutually exclusive. There can be a middle way’ he concludes.