Right now, these are living on your body. But don't worry! They're supposed to be there. They're microbes – and the planet is covered in them. And there are tons of them in the soil because they literally make fertilizer for plants. "These are some of the only things on earth that can do this." We depend on soil for almost all of the food that we eat, and because 90% of the planet's soil could be degraded by 2050, scientists and even agribusiness think microbes could be key to averting a food crisis. So, let's take a journey to the invisible world right under our noses and our feet. To see what happens to soils when microbes get out of whack we can look back to the 1930s in the United States Settlers replaced native grasses with farmland and then intensively tilled, which killed microbes and degraded the soil. After a series of droughts, the damaged soil was easily picked up by the wind and turned into so-called 'black blizzards'. Millions of tons of topsoil just blew away in what came to be known as the Dust Bowl. Although farming methods have changed somewhat, soil degradation is still a global problem. "What we are doing basically is destroying the soil, that is a non-renewable resource." Cristina Cruz specializes in the interactions between plants, soil, and microbes. "What we have been doing so far during the last 200 years maybe, is to use soils as a substrate to grow plants." We've been undervaluing them
and expecting them to stay healthy. But tilling, overusing chemicals, and
climate change are harming our soils. This is a problem for growing food, as well
as resources for clothing and construction. Soil is also key to storing carbon and filtering water. To make soils healthy again we need
to start seeing them as what they are: entire ecosystems teeming with
hidden life, all run by microbes. "And to see microbes in action, we're headed to a farm I help out on near Berlin." "Here we are!" "All this under our feet is topsoil, where most of the insects and microbes live, along with plant roots and small animals." One gram of this can contain millions of microbes. "And a few worms!" A healthy soil will have a diversity of microbes. The most common ones are bacteria, and fungi. One of their most important jobs
is transforming nutrients.
"Every single nutrient cycle on the planet is mostly driven by microbes." Jennifer Wood has a background in soil microbial ecology and studies how microbes affect ecosystems. "None of these cycles really exist in a vacuum. They're all interlinked." One of those nutrient cycles is with carbon. Plants and animals are made mostly of carbon, and when they die, they are broken down by microbes. No microbes, no decomposition. The microbes use some of the carbon to reproduce, storing it in the soil, and breathe the rest of it out, sending it back to the atmosphere. Another nutrient cycle happens with nitrogen, which makes up most of the air around us, and is one of the main nutrients plants use to grow. Plants can't get it from the air by themselves, so they partner up with microbes. And we can find evidence of the nutrient cycle by looking at certain plants, like these beans, which are considered 'nitrogen-fixing'. The beans create these little root nodules, that become home to a type of bacteria. In return, they change nitrogen into a form that the plants can access. Microbes, specifically fungi, also exchange other nutrients with plants. They have very fine roots called hyphae that intertwine themselves with the roots of the plant. “The fungus is really good at releasing things, like phosphorous, from soils, which is hard for plants to get at. So, it does that and exchanges that with the plant in return for things like sugars, which the plant can make through photosynthesis." There's also some evidence this relationship makes the plant more able to withstand drought and disease. In a degraded soil, these nutrient cycles aren't working as well as they could be. Climate change is one cause of degrading soils with drought and extreme weather causing them to dry out and erode. Intensive agriculture can be another cause as pesticides and herbicides kill off beneficial microbes and reduce their activity. The more degraded soil is, the more
chemicals are needed to grow stuff,
degrading the soil even further. "This whole plot of land was intensively farmed for 30 years and you can really see it in the soil. It's super sandy, dry, and degraded. And when you start digging... "It's amazing what you find down there." This is Benni Franz. He's an electro-engineer-turned farmer, and has been on this land for four years. "Intensive agriculture turned this rich soil – which is purely organic matter – into well, mostly sand now." Even though different parts of
the world have very different soils, One thing all degraded agricultural soils have in common, is that they're susceptible to disease. “We don't want those soils to contain many pathogens. So, the pathogen load might be an indicator of a degrading soil. The more pathogens, the worse the soil is." Degraded soils also lose their ability to hold and filter water – are more susceptible to erosion and have less of those beneficial microbes, meaning plants don't grow as well. But soil health is about more than just our food security. "Soil communities and soil health is actually the foundation of all ecosystems, both natural and manmade. If the foundation of something crumbles, everything else comes tumbling down." And agriculture might actually hold the key to making our soils healthy again. "On this same plot of land, not so far away from the degraded bit, years of regenerative agriculture have brought back a lot of microbial activity. The soil looks completely different." This farm is a best-practice example: no chemicals are used, and the
microbes in the soil are thriving. Just look at how beautiful these tomatoes are." No till agriculture leaves soil undisturbed, which allows the microbes living inside the clumps to thrive. Specifically, those fungi hyphae, which are important for soil structure. There can be a kilometer of them in a gram of soil. And cover crops, planted to leave in the ground, provide microbes with carbon to chow down on as well as reduce erosion and nutrient loss. "This is something you're not going to see in most places. This fennel and all these other vegetables — they're not doing anything anymore. They're just kind of hanging out with the microbes. When those old plants are removed, they end up here, in the compost pile. Compost actually adds microbes back into the soil, and encourages those fungal microbes to grow." It can also be made into a liquid fertilizer. "First step is we're going to massage it in, then we're going to feed it on so the bacteria and fungi will multiply, a lot." This compost tea concentrates microbes into a form that can be sprayed on fields. Unfortunately, this kind of farming just isn't possible everywhere. "If you can do it, that's fantastic. It's what we want (in terms of soil health). But the problem is the vast amount of areas where the soil is so degraded that these techniques are not strong enough to recover the soil in due time." Here's where microbes come in on a larger scale. The most common use is as biofertilizers. They're used like chemical-based fertilizer, except they contain fungi or bacteria. Soil degradation is a big enough threat that Bayer – a company known for selling agricultural chemicals – is also interested. "They are currently already used in a number of countries." Frank Terhorst is the Executive Vice President for the crop science division, with a background in Business Economy. "Biological alternatives will certainly be an alternative and will certainly help to reduce chemical fertilizers." The company is also investing in seeds
that have been infused with microbes because delivering microbes along with seeds is the most targeted way to apply them. Seeds can also be planted with a coating of microbes. Conservation organizations are using this approach to restore ecosystems. A problem with commercial microbial products is that the microbes are not specifically adapted to the environment. Non-native microbes could find it hard to survive rendering the process useless. And because these are living organisms, they could cause an imbalance in the microbiome. "This is something we really have to take into consideration, especially with fungi, because they spread faster and they are more efficient in design." Even Bayer agrees. "Just because they are natural, it doesn't necessarily mean that they automatically are not harmful." Since soils are different around the world, we would ideally develop microbial products for specific regions But that will take time and more research. Unfortunately, our soil health is an emergency. "We are going to need it because we have to recover soils. And this is the cheapest way to recovery because we are recovering them while we are maintaining productivity." So, for large farms, biofertilizers are a step above chemicals And where possible, agriculture
that relies on helping native microbes – like on this farm – is the way to go. "Every part of the process here feeds the microbes in the soil, and because of that, this type of agriculture is the gold standard. Fun fact! It takes 1,000 years to create even a few centimeters of top soil. So we have to be super careful with how we use it. If you want to hear more solutions like this one – Don't forget to follow us. We've got new videos every Friday!"
