Last December, on World Soil Day, several organizations (OrganicForest, WERVEL, ILVO, VUB, Agromix, and SoilDiveragro) collectively hosted the 2022 Soil Health Conference – Harnessing biodiversity for better agronomy in Brussels, Belgium. This conference brought together scientists, farmers, and other experts to share the latest findings on soil restoration and practical recommendations for farm workers. Within the science of agronomy, the conference seeks to inspire a transition from chemistry to a focus on biodiversity.
Speakers discussed topics ranging from good practices for restoring soil health to historical research trends of the 20th century. The conference concluded with a discussion on the benefits that farmers can expect from regenerative agriculture.
Dr Kris Nichols, FWWF lead scientist, was invited to Brussels to discuss the mechanisms of soil health restoration in regenerative agriculture. Here are a few highlights from that presentation:
1. Soil regeneration via recarbonization
Hydroponics is an ancient and recently-relevant technique where plants are grown without soil. The nutrients and minerals that their roots would normally tap into underground are supplied instead through a water-based solution.
In her talk, Kris explains that conventional agriculture is like outdoor hydroponics. The world’s soils are becoming increasingly degraded, requiring producers to supply the soil with what it lacks: nutrients, minerals, and water. But this isn’t what we want, she adds.
“What we want to be doing,” she says, “is uniting … that whole physical, biogeochemical world that exists.” Rather than taking apart the system and supplying each component back to the plants and soil, we should view the ecosystem holistically and consider the relationships among the plants, animals, and microorganisms that they need to thrive. Taking a systems approach needs to be “dynamic, innovative, integrated, and intensive.” Soil regeneration via recarbonization, which is the basis for regenerative agriculture and agroecology, is the systems approach we need.
On the importance of soil carbon, she remarks, “it’s the most essential element we have and our only concern is CO2 levels in our atmosphere.”
2. Humility in what we don’t know
“It’s a microbial world and we just live here.”
Relatively speaking, we don’t know much. When you take into account the intricate nuances of all the vast and unseen (to us!) worlds beneath our feet, or the spectrum of sensory stimuli extending beyond what our human senses can pick up on, it makes sense to say that our collective knowledge doesn’t cover everything. Or even most things.
The world of soil is infinitely complex; there may be over 9000 unique interactions happening among soil microorganisms at any given moment, explains Kris. All the elements of healthy soil that we know of and all the ones that we don’t are equally vital for soil health.
“We take a very anthropomorphic approach to what’s happening in a very non-anthropomorphic world,” she says.
This is why we need a systems approach: to allow that world to thrive without reducing it to a collection of the components that we understand. Soil itself is interdisciplinary: it doesn’t separate itself by rocks, minerals, microbes, chemicals, water, carbon, or motion. And we do ourselves a disservice by separating our science into the clean-cut categories of geology, chemistry, physics, and biology. We should treat our science like the thing we are studying.
3. Changing the way we look at organic matter
Some experts predict that it takes about a thousand years to build one inch of topsoil. The parent material weathers gradually over time, migrating up through the soil horizons towards the top layer. Those minerals mix with organic matter and form carbon-rich topsoil. But, as Kris says, we don’t have thousands of years. So what do we do?
When things aren’t looking up, let’s look down instead. Rather than relying on soil to rise up from the parent material, bringing carbon down from the atmosphere and into the soil allows us to rebuild soil carbon in a matter of years, not millennia.
We used to think that we need to focus on humus to sequester soil carbon. But humus, Kris explains, takes hundreds of years to build up and is not very useful for soil. Humus is organic matter high in carbon and nitrogen that is so decomposed it can’t decompose further, meaning that it doesn’t react or change very easily (referred to as recalcitrant carbon). And because it doesn’t change, it isn’t available to organisms and doesn’t play a role in the soil ecosystem.
Soil is mostly minerals, with some organic matter. Roughly half of the organic matter is humus, or nonreactive graphite-like carbon. About a quarter is reactive, proteinaceous carbon, which is what we want to increase with soil carbon sequestration. Not only does this form of carbon enrich the soil and provide food for organisms, some of it will be transformed by microbes into a stable, long-lasting form that isn’t emitted as carbon dioxide.
“Organic matter isn’t what we thought it was but it’s now what we need it to be.”
4. The principles to economic and environmental wealth
The mid-1900s saw the beginning of the Green Revolution – a movement to industrialize agriculture and boost yield in Global South countries to meet increasing demands.
Now, the “Brown Revolution” seeks something different: a return to low-tech practices that align with natural systems and promote ecosystem health. With seemingly opposite goals, the underlying drives behind these two movements run parallel: each is a strategy to feed ourselves and the world, suited to its respective time and place.
Kris introduces eco-functional intensification as a way to reconcile these concerns for ecosystem health with the need to feed the world’s growing population. The six principles of regenerative agriculture – maximizing photosynthesis, biodiversity, reduced synthetic/off-farm inputs, livestock integration, reduced disturbance, and soil armor – are key for economic and environmental wealth, she explains.
Maximizing photosynthesis is more than just growing more plants at once. Farmers can also maximize photosynthesis temporally, growing plants for longer in the year to capture the sunlight that wouldn’t otherwise be used.
The photosynthesis principle entails biodiversity. One crop plant isn’t going to grow for 365 days a year. In order to expand growth throughout the seasons, you need a variety of plants with different niches in the ecosystem.
She explains that adding synthetic fertilizer “outsources the jobs of the microbes,” who normally provide 70-90% of the nutrients taken up by plants. When we rely too much on synthetic inputs, microbial populations decrease and nutrient efficiency follows suit.
In the fourth principle, wild animals are included as livestock. Birds, bees, and bats can all benefit the ecosystem by adding nutrients to the soil through their poop.
Commonly, reducing soil disturbance means minimizing tillage. But there are other strategies too, such as reducing wind and water erosion and managing soil disturbance from animals.
To reduce soil disturbance, we need soil armour. Crop residue provides a physical defense against erosion and protection for the microbial community so they can continue to build and enrich the soil.
5. And lastly,
“It’s not about the practices,” she says. There are no rules. It’s about the health of the system as a whole and what makes sense for each situation and each farm.
Check out Dr. Kris Nichols’ full presentation here:
[Link: Soil Health Conference 5 December 2023 Dr. Kris Nichols (Food Water Wellness Foundation) - YouTube]
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