Did you know that after the oceans, soil is the largest store of carbon, one of the building blocks of CO2? With around 1,500 billion tons of carbon found in soil worldwide, there is more carbon stored in soil than in the atmosphere (760 billion tons) and in vegetation (560 billion tons) combined!
How to sustainably manage our soils
Beneath our feet lies an important tool to combat global climate change. Not only does our soil capture and store carbon and water, it also increases biodiversity, and preserves and increases food security.
Soil is also a very important tool for farmers. They have a key role to play in achieving SDG13 by 2030 and keeping the climate from warming even faster. Bad soil treatment can cause huge amounts of extra CO2 to be emitted into the atmosphere, whereas sustainable soil use presents a nature-based opportunity to capture CO2. The good news for farmers is that taking up this role does not have to come at the cost of decreasing yields or production. Sustainable soil management can contribute to increasing food production, enhancing the nutrient content of food, as well as adapting to and mitigating climate change – all at the same time.
Arjan Koomen, Program Lead Sustainable Land Use at Wageningen University & Research (WUR) where sustainable soil management is one of the key fields of research, acknowledges the importance of the soil in climate change. “We use scientific knowledge to develop nature-based solutions for sustainable soil management that can be used to give advice to agribusinesses.”
How the earth’s soil captures and emits CO2
Plants and trees absorb CO2 from the atmosphere and use the sun to convert it into oxygen and plant biomass, such as roots and leaves, through photosynthesis. Some of the carbon captured by plants is quickly absorbed by the soil when it leaks from plant roots, or is actively excreted, forming a source of food for soil organisms.
In natural systems, organic matter decomposes at a slower rate than the build up of new matter, so the carbon derived from CO2 is stored in the soil, which can retain it for thousands of years. When the soil is disturbed, for example due to tillage or draining of wet areas, the organic matter is exposed to oxygen which accelerates the process of decomposition by microorganisms.
Research into these complex processes is important to improve soil management and soil use. FMO’s knowledge partner WUR is leading the way in this area. Their research focuses on climate mitigation - making optimal use of the soil and crops to capture greenhouse gases (CO2 and N2O) – and climate adaptation, which, in a much wider perspective, also involves developing soils that are resistant to the effects of climate change, such as salinization, erosion and extreme drought.
“To be a successful farmer one must first know the nature of the soil.”
-Xenophon, Ancient Greek philosopher -
Soil management is a term used to describe measures that have a major impact on the health of the soil. Since soils have very diverse chemical, physical and biological properties, it is important that farmers analyze the combination of soil and plant type before they start cultivation. By gathering soil data, analyzing and changing the way they plow, fertilize and plant their land, farmers can improve both soil health and crop production.
In traditional agriculture, fields are plowed or tilled in preparation for sowing. This adds extra oxygen to the soil, which speeds up decomposition processes and also emits extra CO2. Koomen said: "If farmers do not till or plow their soil, or do it very rarely, this leads to a significant reduction of emissions from that soil. They are probably not always aware of these effects, so dissemination of knowledge is very important."
By taking soil samples and analyzing the data before they start the cultivation process, farmers can also handle fertilizers, pesticides, and micronutrients more consciously. Koomen told us: “Because farmers know exactly how much their crops need, they can avoid adding unnecessary substances that damage their soil in the long term.”
Farmers are increasingly experimenting with so-called cover crops. According to Koomen: “In order to prepare soil and fertilize it in a natural way, farmers can plant other crops prior to the primary one. For example, with a potato crop as primary, it works very well if you grow peas a few months prior to sowing the potatoes on that same plot of land. This even has two upsides: you store more organic material in the soil and you might also save on your fertilizer expenditure afterwards.”
There’s still a lot of ground to cover
In the end, it is in everyone's interest to keep our soil healthy. Not only for the climate, but also to ensure that farmers can continue production and continue to feed the world's population.
So why is it that despite its environmental upsides and proven farmer benefits, sustainable soil management is not yet being used by all farmers worldwide? “Over the past few years, sustainable soil management has been a hot topic, but predominantly amongst scientists and policy makers. What is still largely missing is the link to the business community - and thus the farmers who have to actually apply the methods. There certainly are a couple of good examples amongst large-scale agribusinesses, but at the same time there are many "pedal to the metal farmers" who are only focused on producing as much and as quickly possible. Much like in most of the developed world, sustainable soil management is still in its infancy in emerging markets. There’s still a world to win, a lot of ground to cover, in this regard”, says Koomen.
Nevertheless, the topic of sustainable soil management seems to be gaining momentum. Its increased popularity is, amongst others, illustrated by Netflix launching the documentary called ‘Kiss the Ground’. Documentaries like this signal that this area of expertise is being picked up by the mainstream public. And that is a good thing. Another example is the growing constant canopy movement which is being applied by a (group of) farmers in the USA. Koomen remarked, “The fact that some American large-scale agribusinesses are discovering the benefits of crop rotation and sustainable agriculture is a hopeful sign that the methods are moving beyond science and policy, towards implementation.”
What is needed to bring sustainable soil management to the next level?
Because most agribusinesses work with many different farmers from all over the world, they have an important role in convincing farmers to implement sustainable soil management. Agribusinesses need to increasingly link farmer production to the right incentives, because if these companies have the ambition to make their supply chain more sustainable, all the farmers they work with will have to alter their practices.
“The main challenge in transforming farming practices to sustainable soil management is raising awareness and crossing the knowledge gap. We have quite a lot of requests coming in for soil management advice at WUR. The soil-agriculture interaction is a complex system with many variables. In order to scale up, we need to connect more (local) farmers to (local) knowledge institutions.” Koomen told us. He added, “If you want to convince a farmer to change things, you need to reach out and provide them with the right incentives. On the one hand more awareness is needed, but more importantly, governments and businesses need to work together and set the same kind of long-term standards.”
A hopeful development in this regard is, according to Koomen, the increasing collaboration between the policy, science and business sectors. He has observed an uptick in projects where governments, companies and knowledge institutions are trying to tackle the problem of unsustainable land use together. Koomen mentions the example of the Dutch initiative called ‘Groene Cirkels’ (Green Circles) which brings together organizations around a shared ambition to green a certain part of the economy or supply chain. At the heart of every project is the ambition to bring nature and the economy into a better balance and to actively contribute to a better living environment, a circular economy and a healthier future.
Wageningen University & Research translates knowledge on soils into possible measures for sustainable soil management
In line with the increasing interest in the topic of sustainable soil management, Koomen's team of researchers at the WUR have been getting more requests for advice from farmers and agribusinesses. The soil-agriculture interaction is a complex system with many variables. Koomen said: "Soil and the way you should treat it is completely location-specific. There's a wide variety in soil types, regional climates and types of crop. So a request from the other side of the world can be rather challenging. It can be very helpful to look at soil samples data; this gives important information on the amount of nutrients, the structure and soil biodiversity. Based on this information and data, we can derive soil trends and base advice on what should and should not be done to further improve soil health."
There is a high variety in soils which sometimes asks for an analysis to the last detail. "Even at the level of a parcel of land, differences in the soil can be discovered that could possibly benefit from a different approach to cultivation. That is why we need to carefully look for a balance between data and management in which we can give useful advice, that is not too abstract or too detailed," Koomen added.