I’m back at my desk, and back to writing about food production and its environmental consequences. I’ve already touched on soil degradation in a couple of previous blogs, but would like to dive in deeper today. We sometimes use the image of the ground beneath our feet to mean the one thing we can be totally sure of, can rely on with absolutely certainty, but it may not be so.
95% of our food comes from the soil, but about a third of the world’s soil has been degraded by modern farming techniques, deforestation, and global heating. The US Food and Agriculture Organisation warns that, unless new approaches are adopted, the global amount of arable and productive land per person in 2050 will be only a quarter of the level in 1960. According to the WWF, half the topsoil on the planet has been lost in the last 150 years.
What are the main causes?
Water, wind, and farming tillage can all contribute to soil erosion, which means that soil leaves where it is supposed to be – on the land – and ends up in drainage channels, streams, rivers, and lakes. It’s exacerbated by removal of plants and trees, either by deforestation or by the wildfires that are becoming more common as the planet warms. And it can be gradual, or it can be dramatic and lethal, as in the massive mudslides near Santa Barbara last year.
Erosion can be reduced by leaving plants, like alfalfa or winter cover crops, on farmland at the times of year when rain is most likely. The plants help lessen the impact of the rain on the soil, and also provide a conduit for the raindrops to seep into the soil rather than washing off the surface. Contour farming and strip-cropping also help.
LOTS more about soil erosion on this website.
- Loss of Quality
Soil depletion due to some farming practices leaves the soil less fertile, mostly by reducing the microbial activity of the soil.
Deforestation is a triple environmental whammy. Trees provide generous amounts of leaf litter and fallen branches to create humus, which is important for the soil’s aeration, water holding capacity, and biological activity like worms. Logging worsens erosion. And of course the loss of those trees reduces the earth’s capacity to convert CO2 back into oxygen through photosynthesis.
- Excessive Use of Fertilizers
Excessive use and misuse of pesticides and chemical fertilizers kill the multitude of tiny organisms, like bacteria and other micro-organisms, that bind soil together. The fertilizer’s chemicals also denature essential soil minerals, leading to nutrient losses from the soil.
- Industrial and Mining Activities
Mining removes plant cover, and releases a toxic mix of chemicals like mercury into the soil, poisoning it. Industry releases toxic effluents into the air, land, rivers and ground water that pollute the soil.
As our cities grow, we pave over more and more green areas with concrete and tarmac. As well as replacing greenness with greyness, all those non-absorbent surfaces increase runoff, which in turn increase erosion. And it’s not nice rainwater – by the time it has washed down our streets, it is polluted with oil, fuel, tyre rubber, and other junk.
I’ve heard that in China, the plastic that they use to cover fields is not removed when no longer needed, but ploughed into the soil, to the extent that many fields now appear white rather than brown when bare of crops. I haven’t been able to verify this exactly, although this article describes a similar problem. Yuck.
- Seawater Inundation
As icecaps melt and sea levels rise, more coastal areas are being flooded, which contaminates the land with salt. You might remember from your history lessons that salting the earth is what victors used to do to render land uninhabitable because the salt would prevent crops from growing.
Well, there’s more, but that’s enough to be going on with, before we get too overwhelmed.
How do we turn this around?
First, what are we aiming for? Here’s a soil enthusiast talking about what soil should look like.
And second, what can we as individuals do to promote this lovely, rich, wormy soil?
- Do our bit to curb industrial farming.
Eat less meat and dairy, and more fruit and veg, to reduce the need for tilling, multiple harvests and agrochemicals. Eating lower on the food chain is a much more efficient use of our agricultural land.
- Bring back the trees.
Plant trees, and vote for policies that promote sustainable forest management and reforestation schemes.
- Stop or limit ploughing.
In your own garden, adopt a no-dig policy. Support farmers who adopt a zero-tillage strategy, and make sure no soil is left exposed by sowing cover crops directly after harvest.
- Replace goodness.
Compost, pony poo, seaweed, whatever you can find that will enrich your soil.
- Leave it be.
When land is left to recover, nature does a marvellous restoration job. Hydroponics, vertical farming, and switching to mostly or entirely vegan diets all reduce our currently insatiable demand for land for food production.
If you doubt your power to make a difference, don’t! We’ve mostly ended up with these challenges through the billions of micro-decisions we all make every day about what to eat, and who to buy it from. So we need to start making better micro-decisions, and spreading the word. We all make a difference, all the time – make it a good one!