Globally, 12 million hectares of agricultural land are lost to soil degradation each year. As an ecologist, I work with farmers and growers in the field and have seen how agriculture can help solve this global soil crisis.
A 2019 report by the UK government’s Environment Agency estimated that 17% of soils in England and Wales showed signs of erosion. An estimated 4 million hectares of farmland were at risk of compaction, where soil is pressed together by grazing animals or heavy machinery, squeezing out air pockets between soil particles. A further 300,000 hectares of land were contaminated with contaminants.
But soil health statistics are difficult to quantify, and regular, systematic sampling strategies to assess soil function are rarely adopted by governments in the long term.
Farmers are increasingly considering practices like regenerative agriculture that reduce soil damage and even help regenerate it. Planting green manures, reducing or carefully managing livestock densities, direct seeding and reduced-till strategies, as well as planting trees and increasing organic matter, can all help. Farmers and soil scientists are also beginning to use smart technology to reliably measure changes in soil condition.
Although I have been doing soil research for some time, it is only recently that I have become aware that soil assessments, especially those recommended for farmers, often focus on physical and chemical measurements, without much attention to the diverse communities of organisms (from microbes and fungi to earthworms and plants) that live in the soil.
Sampling strategies typically fail to account for the enormous variation that occurs in soil conditions, even within a field or between seasons. Detecting changes over years or between management practices is often prohibitively expensive for farmers, as large numbers of sample replicates are required.
New research and technology can help close this gap. Here’s how:
1. Satellite sensors
Intensive farming contributes to the degradation of healthy soils. Bare soil is easily eroded by wind and rain, and extreme weather events are more likely with climate change. Ploughing can break up microbial networks of fungi, bacteria and other similar organisms, changing the way soil particles form and fit together and releasing carbon stored as organic matter.
Heavy grazing can increase compaction, which reduces the soil’s water-absorbing capacity. The introduction of synthetic chemical fertilizers and pesticides can harm invertebrates and microbes above and below ground, while releasing harmful pollutants into rivers and seas.
Satellite sensors have revolutionised the data available for visualising landscapes, including farms. It is now possible to use satellite imagery alongside innovative agri-tech to monitor plant growth and disease, soil degradation and water content, and see changes over time. This allows for better decisions to be made on how best to farm sustainably without further degrading the soil in certain places.
2. Soil sensors
The ground beneath our feet is teeming with life, and most terrestrial organisms rely on the soil for nutrients or fertilize it through excretion and decay. By using sensors to monitor how soil conditions change, we can see whether they are more or less favorable for certain organisms to live.
Soil sensors can be used without disturbing crops or sending material away for lab analysis. With calibration, highly portable, handheld near-infrared (NIR) sensors can detect soil organic matter such as decayed plants or manure – a good indicator of healthy, fertile soils.
At Plymouth we mount sensors on manned or autonomous drones and robotic platforms. This is a quick and easy way to collect samples and information about organic matter, even on rough terrain. Smaller and cheaper robotic “dogs” are better suited to moving along the bottom of hedgerows or through rows of densely packed shrubs, such as lavender.
In the future, static field sensors could be powered by harnessing energy released by chemical reactions taking place in the soil microbial community itself.
3. Animal sensors
Individual sensors, similar to Fitbits and other activity loggers, are increasingly used to monitor animal welfare, especially in indoor farming systems, for example with cows. Sensors that detect movement can also be used with sheep and cows grazing outdoors.
These sensors tell farmers where and how animals are moving in the environment. This allows them to locate areas where soil compaction is likely to occur, so they can address it.
In rural areas, poor internet connectivity can limit the use of these sensors. That’s why we’re working with farmers in high-altitude areas like Dartmoor using LoRaWAN (Long Range Wide Area Networks). The sensor transmitters are attached to fence posts or animals and use low-power radio frequencies to relay information directly to farmers and researchers.
4. DNA detection
Another exciting development is new mobile DNA-based technology. Small handheld sequencers and machines that amplify and quantify DNA, as well as mobile laboratories, allow farmers to take and sequence samples in the field and in a short time frame.
Fungal diseases that live in the soil and can destroy crops, such as Fusariumcan be detected using simple methods similar to COVID testing. Using hand-held sequencers, I have worked with organic growers to capture images of microbial communities in fields with different crops and management practices. These methods take just a few days to produce results, meaning the impact of changing practices can be seen quickly.
New technology opens up possibilities for faster and cheaper monitoring of soil functions. However, in order to determine the most suitable technology, it is very important that researchers and professionals work together to come up with simple solutions to monitor the condition and health of our soils. This will enable farmers to determine the most suitable management practices to protect their soils for future generations.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Jennifer Rowntree works for the University of Plymouth.