Let’s dig into the fascinating hidden world beneath our feet and discover why it is so important to save soil.
Choosing to save soil might be one of the most important things on earth (excuse the pun). But despite it be utterly fascinating, we also know very little about soil. In fact, we know more about the surface of the moon than we do about what goes on in the soil beneath our feet.
Lately, the topic of saving soil has become more and more prominent. Here we will take a closer look at what is so interesting about soil, and look at five important reasons to save soil.
WHY SAVE SOIL?
“Despite all our accomplishments, we owe our existence to a six-inch layer of topsoil and the fact it rains” – Paul Harvey
As gardeners, we know that soil is essential because it’s what we plant our plants in to, and where our plants get their nutrients. One of the most biodiverse and abundant ecosystems on the planet, the soil is essential for almost all life on earth.
Despite this, we know very little about the soil and how it works. Far from being an inert substance that holds up our plants, the soil is actually one of the most diverse ecosystems on the planet.
There are so many reasons why we should save soil for the good of humanity and the planet. Here I have distilled it down into five major points. So here it is, five reasons why we should save soil. Stay tuned for the last, because you might be surprised!
1. IF WE SAVE SOIL, WE SAVE WATER
Good, healthy soil that has not been routinely ploughed or drenched in chemicals is a valuable resource when it comes to water management. The organisms within the soil help to maintain good soil structure.
Soil with good structure is porous – meaning that it contains many pores. These pores are created by the organisms in the soil that move around and excrete sticky substances. This forms aggregates, collections of soil particles that are stuck together. As the aggregates are formed, pores are opened up between them.
Water can then travel down through the pored of the soil, in much the same way water moves through a sponge. Some water clings to the soil aggregates, and the rest is washed into waterways or the groundwater. The result is that well-structured soil both retains moisture and stays well-aerated. This helps to build resilience against drought and flooding.
SOIL FILTERS WATER
As water moves down through the soil’s pores, it gets filtered. Particles are left within the soil, and bacteria and fungi can remove pollutants, organic matter and even heavy metals from the soil. The result is that we have cleaner water in our streams, rivers, lakes and seas.
This means that those ecosystems will be healthier and able to support more life and more biodiversity. It also means that we will spend less money trying to clean water to make it safe for our consumption.
One important type of soil is Peat. At the moment this is still mined in many areas for use in horticulture and as a fuel for fires. It’s estimated by the IUCN that 70% of the UK’s water comes from upland areas dominated by peat bogs. The soil in a peat bog is an incredible water filter and saves the UK economy millions each year. And that’s just peat. It should be noted that peat is different from “normal” soil and does not contain much soil life, it is also waterlogged in its natural state.
Resilience to Erosion and Compaction
Soil structure that is built by the soil life is very resilient. We have already discussed how aggregated, porous soils retain water and air. This makes them resilient against drought and flooding.
Healthy, well-structured soils also hold together extremely well, meaning that they are less prone to erosion and compaction. Erosion is when the soil is washed away by excess water, or blown away by strong winds. The result is that we get sediments in our waterways which can cause clogging. We may also get sediment deposits into the sea which can harm marine life. It’s thought that soil degradation and erosion costs around £1.4 billion a year to the UK economy alone.
Compaction is also a problem in unhealthy soils. The actions of machinery, animals or any kind of heavy use over soil will cause compaction over time. Even where soils are routinely dug, we find compaction layers or pans, under the surface where water can be trapped. These form small underground reservoirs that harbour diseases-causing microbes.
2. SOIL CONTRIBUTES TO BIODIVERSITY
Soil is one of the most biodiverse ecosystems on the planet. One handful of healthy garden soil can contain as many lives as humans who have ever lived on this planet. That’s a mind-boggling amount of tiny little lives. Not only are there a lot of things living in the soil, but there is also a lot of diversity as many as 50,000 different species in a single gram.
Biodiversity is one of the things that protect our planet. We cannot possibly hope to understand the role that each individual species plays within an ecosystem, but we do know that ecosystems that are biodiverse (containing a lot of different species) are the healthiest and the most resilient to change. The importance is almost always in the way that species interact with one another and with their environment. This is particularly true in soil.
Biodiverse soil helps to maintain good soil structure as we looked at in point 1, and helps to feed our plants and fights pests and diseases. Pests and diseases can only proliferate in ecosystems that are not in balance. If an ecosystem is healthy and biodiverse it will be in balance. This will give an ecosystem all the tools it needs to be able to keep pest numbers under control and maintain the health of the other organisms. If we save soil ecosystems we are helping a major contributor to global biodiversity.
3. Save Soil for Global Food Security
It is estimated that 95% of the food we eat depends on topsoil. Without soil, we simply wouldn’t be able to survive. In the past, agriculture was respectful towards soils. Farmers would leave fields to pasture, allowing them to build organic matter through grazing and simply not being ploughed.
However, during World War II, there was a big push to produce more food in the UK. This was because enemy forces were limiting food imports from other countries, which put a huge demand on British agriculture. At the same time fertilisers, fungicides, herbicides and pesticides were being developed in warfare laboratories, which helped to intensify agriculture. Along with the jump forward in technology, this leads to the industrialisation of agriculture. Its primary aim was to produce as much food as possible, not to look after the land.
Chemical use and ploughing cause a huge amount of damage to the top layer of the soil (the topsoil), where most of the life resides. Because of this, we are losing the soil’s natural ability to release nutrients from sediments, maintain soil structure, fight pests and diseases and filter water. The effect of which is that we need to use more chemicals, and more costly industrial practices to produce the same results.
4. Healthy Soil Grows Healthy Food
It’s no secret that people are less healthy nowadays than they were 100 years ago. In fact, during World War II, and the push for more British Grown crops, people were encouraged to “Dig for Victory” by growing their own food. During this time, when food was still being produced organically by home growers, there was a significant reduction in the number of chronic diseases reported. It is possible that this is due to people not seeking help for such conditions during wartime, but it’s considered more likely an effect of eating fresher, more nutrient-dense food.
Crops that are grown on healthy soil, without the use of chemical fertilisers, pesticides, herbicides or fungicides are healthier for us. They contain a higher density of nutrients, antioxidants, vitamins and good bacteria that help to bolster our gut biomes.
Organic, homegrown foods are one of the best sources of nutrients and healthy bacteria as they are often eaten fresher than if you were to buy them. Over time, nutrients in food start to degrade, so food that is eaten as soon as it is harvested will be the highest in nutrients, antioxidants and vitamins.
Fertilisers will produce fast growth that is not nutrient-dense. In fact, a test on some Aubergine grown in an industrial greenhouse and fed on liquid fertilisers found that whilst the fruit looked large and healthy, it contained less than 20% of the nutrients found in organic aubergines grown in healthy soil.
5. SOIL StorES CARBON
This is the big one. Soil is one of the largest carbon sinks on the planet, holding around three times as much carbon as living plants, and twice as much as the atmosphere. Soils that are rich in organic matter, and soil life are a far greater store of carbon than depleted soils.
Organic matter within the soil can be defined as anything that is alive, dead or very dead. All living things are made up of carbon. We ourselves are carbon-based. So all the organic matter in soil is also carbon-based. Therefore, the more organic matter there is in the soil, the more carbon will be stored.
Soil is a relatively stable carbon sink unless it is being dug or ploughed. The picture below shows atmospheric carbon in September vs April. The red colours indicate high levels of atmospheric carbon in the Northern Hemisphere during April. This is around the time that ploughing takes place. By September, the crops in the field have drawn down a lot of this atmospheric carbon and pumped some of it down into the soil. It’s amazing to see how much carbon is released simply by ploughing the soil.
How Do Soils Build Up Carbon?
When plants photosynthesize, they are continually converting atmospheric carbon into carbohydrates (carbon) and oxygen. The oxygen they release back into the atmosphere (for this we are incredibly grateful), and the carbohydrates are used for the plants’ growth. Some of the carbohydrates however are used as currency, to trade with the life in the soil.
Plant roots pump as much as 40% of the carbohydrates produced during photosynthesis down into the soil to feed the soil life as something called root exudates. In exchange, the soil life releases nutrients from the sediments in the soil, helps the plant find water, fights off pests and pathogens and maintains good soil structure. These services are obviously valuable to the plants – since they pay so much for them!
The life within the soil is itself a form of carbon. The organisms within the soils are constantly eating and excreting one another, building organic matter all the time. If the soil is dug or ploughed, a lot of these creatures will be killed, and a lot of the carbon in the soil will be oxidised and become atmospheric carbon (Carbon Dioxide).
So How Can We Save Soil?
We much try to reduce disturbance to the soil. Digging up our soils to improve their structure is almost like chopping down all the trees in a forest to help the forest. It kills soil life, releases stored carbon and destroys the carefully built soil structure.
As the soil life will come to the surface of the soil to feed and forage for freshly lain organic matter, we should add organic matter to our soils by applying an annual mulch. This recreates the natural process of leaves falling to the ground during autumn. It will build organic matter, feed the soil life and produce an environment that is healthy for your plants.
Stop using chemicals. This one might seem obvious – anything designed to kill is never good news for our soil life. But here I am also referring to fertilisers. Liquid fertilisers, even organic ones, can interrupt the cycle of reciprocity between plants and soil life. If plants are able to get nutrients without giving away carbohydrates, they will. The resulting growth will be fast as the plants keep all the carbohydrates for themselves. But the soil life will start to become starved and the plant will no longer benefit from all the other incredible services that healthy soil provides.
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