My scientific view on the "Save Soil" movement

Recently, I came across a “journey to save soil”. YouTube’s algorithm made me aware of the Indian mystic Sadhguru, who will travel across 25 nations on his motorbike to raise awareness for soils. At the time of writing this post, he will be in Paris, having already visited Austria, Germany, Italy and many other countries. Sadhguru is an Indian mystic and spiritual guru who founded the Isha Foundation. This foundation aims to improve people’s physical and mental well being, mostly through using traditional Indian practices, such as Yoga. The internet reveals that Sadhguru’s net worth is about $25 million USD, which is apparently double than the foundation’s monetary collection. It seems, as if he is only one of many surprisingly wealthy Indian gurus. Be it as it may, Sadhguru is organizing a concerted action to save soils, which is also the reason for him touring Europe. In my opinion, too many public influencer and leaders focus only on climate change and the increasing concentrations of carbon dioxide in our atmosphere. Of course, the list of all our global environmental issues is much bigger than that, and includes things like air and water pollution, deforestation, plastic waste, but also bad governance. Soil degradation is closely related to all of the above-mentioned concerns. Air and water pollution, loss of biodiversity, deforestation…. These things will automatically amount to decreased soil health and increasing soil degradation. Globally, between 1 to 6 billion hectares of land are degraded. Keep in mind that the global land surface is 13 billion ha big, of which around 5 billion ha are classified as agricultural land by the FAO. This means that most of our agricultural land is already degraded in one way or another. The term “degradation” is an umbrella term which includes various conditions such as salinization, desertification, loss of soil carbon, soil compaction and many more. The most obvious effects of soil degradation are yield decreases, which are already happening on 20% of all agricultural land. More land is also being lost due to the outward expansion of cities and climate change. There are many valid reasons for saving our soils, and any effort towards reaching this goal is welcome. Next up, I put on my “soil scientist hat” and watched one of Sadhguru’s YouTube clips where he explains his ideas. I wanted to know if I will also agree from a scientific standpoint with what he had to say. After all, we recently learned how much mumbo-jumbo is floating around in the ether of knowledge. The video, which I partially transcribed, can be found here:

https://www.youtube.com/watch?v=SIPrZGUso1A

1:37

“Humans being problem is that they are ecology […]. It is only because of microbial life that there is life. Otherwise trees cannot be alive. See, right now this tree is there. Don’t do anything. Just rip off all the leaves. Don’t damage the tree in any other way. Just take away all the leaves. Again it will try to sprout. Take it away on a daily basis. Within 6 month, 1 year, this tree will day. You know why? Because it doesn’t have cash to buy food from the microbes. Unless it gives them carbon sugars, it [the microbes] won’t give them nourishment.”

This is a very holistic view of plant-microbial associations and their importance for one another. But it is also a very realistic depiction of reality. Since the last few decades, the importance of soil microbes for plant growth and plant biodiversity has been increasingly acknowledged. Soil microbes have been described as the “unseen majority” which shape our aboveground environment. How do soil microbes interact with plants? Microbes are major players for making nutrients available to plants. For example, denitrifying microbes are important for providing mineral nitrogen (ammonium & nitrate) to plants. Arbuscular mycorrhizal fungi and phosphate solubilizing bacteria are important for the phosphorus uptake of plants. Technical speaking, agriculture systems are not limited by total nutrient concentrations in soils, but nutrient availability, highlighting the importance of microbial turnover of nutrients. At the same time, beneficial soil microorganisms and symbionts protect plant roots from pathogens or even induce systemic resistance across the whole plant. Up to 20% of photosynthetis products are secreted as root exudates, which attracts and feeds desired soil microbes. We see that Sadhguru’s claims make perfect sense. Continuously removing the leaves from a tree would, amongst other things, also prevent the roots from feeding and attracting the soil microorganisms which are required to keep trees alive in a natural ecosystem.

That being said, I have to mention that plants can also be produced under sterile conditions. But this so-called in vitro culture works only under laboratory conditions and only if nutrients are provided via specially formulated nutrient mediums. However, even under these conditions, plants carry their very own endosymbionts.

3:11

“But now, the microbial life down there, on an average, the UNAF says, on average, around 27,000 species of microbes are going extinct per year. […] If it goes at this pace, in another 30 to 40 years, we will reach a place, where if you want to revive this soil, it will take 150 to 200 years.”

I could not confirm this exact number of microbial species, which goes extinct every year. But it sounds plausible. To date, we only know about 1 to 10% of all fungal species. The numbers are probably similar for bacteria and viruses. The World Wide Fund for Nature (WWF) states that it could be even up to 100,000 species which go extinct every year. Additionally, we know very little about the functioning of soil microorganisms. Even if we identified a species taxonomically, we often have no clue about its functioning. But what we know is that a loss of soil species is correlated with decreased plant productivity.

10:30

“[The extinction of microbial species] started in the last 100 years of industrial agriculture. But I would say in the last 35 to 40 years this industrial level of agriculture has become universal across the world. Earlier it was only in segments in certain countries but now it spreads everywhere. When I say industrial level of agriculture, whether it is yielding in that scale or not is not the question. See, right now the organisms here, the only food they can eat is organic content. Where will the organic content come from? Here you see all these leaves, dry leaves, falling down. We won’t pick it up nor sweep it away. We leave it like that it’ll become part of the soil. It is only the green litter from the trees and other… whether it’s a grass or bushes, whatever… or the animal waste, which can put organic content into the soil. Do one thing: Fly from Coimbatore to Delhi and every 5 minutes you look out of the window. Just tell me how much greenery is left in the country […]. The whole country looks like a brown desert. So where is the organic content? Well, unfortunately city people are talking, you know I’m doing compost in the city. My vegetable compost is very rich. We know that. But is that a solution? It’s very cute of you […] but it’s not a solution for world’s agricultural land. Isn’t it? In every land, there must be enough organic content being generated. This was naturally happening because every farm had trees and animals, always. [But now:] No trees, no animals, only tractors. Tractors are ploughing anywhere between 12 to 14 inches deep and most of the life, 87% of the life, depends upon 15 inches of topsoil. It all comes from that. So we’re ploughing it like this and leaving it open to kill them, so that’s why this is happening. You need organic content, that means you need trees and you need animal waste to happen.”

Here, Sadhguru explains a part of the carbon cycle. If we want to see increases in soil carbon levels, we will need plants that fix atmospheric carbon dioxide and turn it into biomass. Urbanization is doing the exact opposite. Biomass is removed and soils are compacted and sealed. However, there are efforts which can improve the urban ecosystems and even allow urban food production. I’m talking about urban agriculture, which is the production of food within urban boundaries. There are many examples around the world where greening of the cities improved the local climate and wellbeing of citizens. With Cuba, it even enabled an entire country to address food insecurity and reach a high level of self-sufficiency. Research shows that many suburban cities could reach certain levels of self-sufficiency when dedicating urban land to food production. Here, I would like to say that urban dwellers composting their food and growing their own vegetables can indeed be a solution. It just needs to be done on a larger scale. Just like agro-forestry. This is the concept which Sadhguru mentions next. Agro-forestry describes the integration of trees and shrubs into agricultural systems. This system provides multiple benefits to the environment, which will also result in increased soil carbon. Sadhguru also mentions plowing and its detrimental effects on the soil biota. Plowing is an excellent practice to establish a nice seed bed. It will also de-activate a large percentage of soil microorganisms, including soil pathogens. One of the best pesticides is made of steel. It’s called a plow. Still, plowing will inevitably remove a large fraction of the soil carbon through increased oxidation. Using alternative methods, such as no-till, are best practices for soil carbon sequestration. Combine this with agro-forestry and soil carbon inputs increase even further.

13:30

“I remember this when fertilizers first came, I was living on farms at that time, when the fertilizers first came, 35 to 40 years ago. The company sales managers were coming and explaining to the farmers in the village where I was how these trees must be taken out. Because if you put fertilizer in the field and you have a tree in the farm, it has aggressive root system, it will take away all the fertilizers. Millions and millions of trees […] were taken out at that time because everybody thought it's eating up the fertilizer. But they did not understand it is fertilizing the soil all the time. It is loosening the soil structure all the time with its root system. So, we are paying the price for this. This damage has been on for over 100 years in many parts of the world. In India it is about 30 to 40 years old. In 40 years we have come to this place where we are where our organic content is less than 0.5% in 62% of the land. When the minimum set for calling soilless soil is 3%. We are less than 0.5%, we are at the verge of desertification.”

About 9% of the global land is at high risk of desertification. The risk factors for this classification are more complicated than only looking at the soil carbon content. After all, soil carbon concentrations of healthy sandy soils can be very low, even around 0.5%. Nevertheless, carbon loss from arable lands is an actual problem which is projected to increase further. There is also a connection to mineral nitrogen fertilization. In theory, mineral nitrogen fertilization leads to the sequestration of organic carbon in soils, because it promotes the growth of plant biomass, which increases the carbon pool. However, over-fertilization is likely to have the opposite effect. If nitrogen input surpasses a plant’s requirements, it can boost soil microorganisms which will cause increased CO2 emissions from soil. Ideally, fertilization is done through monitoring soil parameters, rather than choosing the highest yield curve. Of course, this has also effects on climate change. Soils represent a large sink of CO2, which released 186 Gigatonnes of CO2 due to the land use changes of the past centuries. This phenomenon can be reverted, for example, when using sustainable land use practices. One movement claims that soils have the potential to sequester 4 per mille soil organic carbon per year, playing a significant role for climate change mitigation.

36:25

“We are not saying no fertilizer, no pesticide. These are all impractical things right now. They will not work. Tomorrow morning, if you stop all fertilizer and pesticide in the country, you will be producing 25% of the food that you are producing right now. That’s a disaster. That’s not the way to go. As you increase the organic content the need for fertilizer will come down.”

This is a really important statement. It is nearly impossible to remove fertilizers and pesticides from our current agricultural systems without inducing a global famine. Even after many years of gradual transformation, organic agriculture might not become a reality. Instead, I would put my hope into the development of new fertilizer formulations, such as slow-release technologies. This way, the nutrient recovery could be enhanced while reducing the environmental impact and potentially mitigating carbon loss due to excess nitrogen fertilization. Mineral nitrogen could be produced through green ammonia, which is produced through green hydrogen.

To conclude his interview, Sadhguru’s proposed solution for saving soils are:

Subsidization and incentives for farmers to increase their soil carbon (e.g., via tree planting or cover crops (or carbon offsets)
Constitutional laws that save and protect soils.
To reach this goal, half of the world should talk about soils for 100 days. This wave of interest would promote the necessary change.

From a soil scientist's perspective, I can only agree with Sadhguru’s message and the Save Soil movement. Furthermore, I think we should keep talking about soils even after day 101.