6 Ways We’re Letting Our Soil Die – And How We Can Save It
July 18, 2018
Unless you’re an avid gardener, you probably don’t give much thought to soil. It’s that dark muddy stuff that dirties your shoes. But farmers are utterly reliant on it to grow most of our food crops and to raise livestock on pasture it nurtures.
So we are all reliant on soil for our breakfast cereals, our milk, our beef…and much more. Are farmers treating the soil with the respect it deserves, though? Here are six soil concerns – and some solutions.
Less matter
Organic matter is the lifeblood of a healthy soil. But a government survey this year found that just a third of farmers keep track of it. The organic matter gets into the soil through the decomposition of plants on the soil surface (the stems and leaves after a crop has been harvested), from living and dead soil organisms, or by adding compost or manure.
As it decomposes into humus, nutrients are released back into the soil and become available for future crops. Organic matter helps the soil to hold water, aids in reducing soil compaction and improves soil structure.
Britain’s garden allotments are significantly healthier than intensively farmed soils. Allotment soil has a third more organic matter, according to one study. Three-quarters of allotment holders add manure to their soil, 95 percent add composted garden waste and many add organic-based commercial composts.
But many non-organic farmers don’t add enough. Intensive, crop-growing farmland needs frequent applications of manure and compost because continuously harvesting crops depletes soil humus.
(Photo: Matt Cardy/Getty Images)
Fewer little rotters
Without an army of soil-living rotters – fungi, bacteria, worms, mites and more – plant material would never decompose to produce humus, the dark, nutrient-rich part of the soil. These little rotters are the original recyclers and we destroy them at our peril. Dr. Maria Tsiafouli of Thessaloniki University has found that intensive farming reduces their volume by as much as 50 percent. Earthworms, mites, and springtails, in particular, have declined.
“These losses make agricultural land less healthy and more vulnerable to pests and diseases,” says Dr. Tsiafouli. That’s something the farming industry needs to take heed of; it might eventually threaten the functioning of farmed soils. The solution? Add far more organic matter to help the rotters thrive.
Water runoff
Rain percolates into soils if its structure is intact. But where the structure of the soil has broken down, it runs off fields, taking some of the soil (and any pesticides and fertilizers it contains) into watercourses. Soil depositing on riverbeds damages the spawning habitat of fish and can kill aquatic plants and animals.
Drive along a country road in autumn and look at the mud running out of field gateways. Rainy autumn harvesting of late-maturing crops such as maize doesn’t help. Nor does soil compaction – when soil particles are pressed together – which reduces rain infiltration and soil aeration, both essential for crop root growth.
With increasingly heavy field machinery, compaction worsens. A tractor in the 1940s weighed perhaps four tons; today they can be 10 to 20 tons.
Soil degradation in England and Wales is estimated to cost up to £1.4bn annually. The solution? Planting fast-growing cover crops on bare soil between main crops is now an EU requirement. Lighter-weight field equipment would help. So would less maize growing.
(Photo: Maigheach-gheal)
Killer sprays
Farmers have to contend with an array of food-crop pests. Some of these are fungi, common in our warm, damp climate, smuts, mildews and rusts.
The usual treatment is to spray fungicides. But many fungicides are only effective at preventing outbreaks of fungal disease rather than treating infected plants. And fungicide resistance is increasing, just as resistance to antibiotics is.
Fungicide applications also kill hugely beneficial soil mycorrhizal fungi, which live with plant roots and garner minerals and nutrients from the soil to aid their growth.
The solution lies with more organic farming methods, using less harmful chemicals, and inbreeding disease-resistant crop varieties and – in the longer term – using genetically modified varieties.
Soil erosion Exposed soil and windy conditions don’t mix. As our climate warms and storms become more frequent, exposed soils are vulnerable to erosion.
Ever since Jethro Tull invented the mechanical seed drill in the 18th century, the land has been plowed.
But why not leave any soil mixing to crop roots and the natural soil fauna? Unploughed soils have more organic matter, more aeration and less tendency to experience drying out or waterlogging. And they get less compacted because less heavy equipment runs over them.
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“No, till” farming is already popular in the US, and it’s becoming more common here. The seed for the next crop is drilled directly into the unploughed soil. “It’s better for retaining soil moisture and eliminating soil erosion,” says Jake Freestone, farm manager on the Overbury Estate in Gloucestershire. “No-till is a win-win for me.”
Biodiversity under threat
Name our richest wildlife habitat. Broadleaved woodland? Lowland heath? The soil is far, far richer: a habitat for huge numbers of bacteria, algae, fungi, worms, insects, small vertebrates, and plants.
Underneath arable crops there might be five tons of living organisms per hectare; under grassland, it might be 20 tons per hectare.
Yet conservationists rarely mention soil. And the UK’s State of Nature Report, which pools data from more than 50 nature conservation and research organizations “to give a cutting-edge overview of the state of nature”, hardly mentions it.
But soil biodiversity is under threat across 56 percent of the EU’s land area, its animal populations reduced by as much as 50 percent on intensively managed farms.
“The problem for conservationists is that soil is a bit out of sight, out of mind with a paucity of flagship species,” says Matt Shardlow, CEO of Buglife, a charity whose motto is: “Saving the small things that run the planet”. He adds: “It’s also hard to measure soil wildlife health and decide what’s important”.
One thing is for certain: we can’t risk playing fast and loose with our soils. As US president Franklin D Roosevelt once wrote: “The nation that destroys its soil destroys itself.”
Dr. Malcolm Smith is a former chief scientist at Countryside Council for Wales and the author of ‘Ploughing a New Furrow: A Blueprint for Wildlife-Friendly Farming’ (£18.99, Whittles)