Healthy soil is literally the foundation for a healthy food system and is a leading indicator for many key metrics around sustainability and ecological health. As a result, soil health is inextricably linked to plant, animal, human and global health.
But topsoil depletion is far outpacing the capacity to generate new soil, and in much of the world, soil is being inundated with chemical fertilizers with much of the soil organic matter being harmed in the process.
But human health problems as they linked to soil health are typically related to water contamination and an over lack of biodiversity in the soil, which creates a negative feedback loop to further detract from soil quality. Farmers are faced with an ever-growing number of solutions to these concerns but lack creative financial tools to adopt them safely.
We’re in the middle of a paradigm shift in soil health practices, with some sustainability protocols that harken back to preindustrial agriculture that oftentimes deliver very good results in terms of health consequences as well as positive economic consequences as consumers are becoming more conscious about what they buy and it was produced.
There are three major factors driving this shift.
The topsoil apocalypse
One of the major problems we’re facing a huge loss of topsoil. About 2 billion hectors of soil have been degraded in the last few decades, equal to about 5 billion acres. That’s a loss of 50% of the agricultural supply in the last 50 years. And this rate is accelerating.
There are varying estimates as to what that means on the farm level. Some farms are losing a million tons of soil, or one ton per acre, per year up to 30 tons per acre per year. Water erosion is a huge part of this, caused by overgrazing and deforestation.
Whatever the total, this is happening at an exceptionally fast rate. It takes many years to generate this topsoil, so this isn’t coming back anytime soon. Soil in large part comes from the erosion of rocks and sediment, so it takes 500 to 1,000 years to generate three centimeters of topsoil. So, if we continue losing it at this rate, all of our soil will be gone in just 60 years.
This problem is global.
The U.S. is losing soil 10 times faster than the natural replenishment rate, but China is losing it 30-40 times faster. This equates to a direct cost. Erosion in the U.S. costs about $37.6 billion each year in productivity losses, and worldwide this damage worldwide is estimated to be about $400 billion per year.
Where does this all go? Nearly 60% of this eroded soil ends up in rivers, streams and lakes, making those waterways more prone to flooding and, due to the fertilizers and other inputs we’re using on the farm, delivering more negative consequences in the water and where that water goes. Of course, agriculture activity expedites the loss of topsoil, just creating a chemical snowball.
Falling input efficiency
It’s also important to note of nitrogen use efficiency and the fact that we’re using really a lot more nitrogen and fertilizers than we need to be. According to BAS Global, less than 50% of applied nitrogen is absorbed by plants, so those are chemical inputs that are being totally wasted from an agricultural standpoint.
But fertilizer is a massive market.
According to some estimates, the fertilizer industry is worth about $150 billion, with nitrogen alone worth as much as $200 billion. And less than half of that is actually being absorbed by the plants.
In short, we’re using more fertilizer than we need and the unit economics of that nitrogen is not working as well as it could be. We’re seeing diminishing returns from what we are using.
A lack of biodiversity
Healthy soil depends on a vibrant range of life forms and together these bacteria, fungi, tiny insects, earthworms, etc create rich biodiversity. But we’re seeing a decline in the diversity of organisms that are present in soil and that’s affecting multiple ecosystem functions.
In short: As soil biodiversity increases, the multi-functionality of that ecosystem increases. It gets better plant diversity, decomposition, nutrient retention, nutrient cycling and everything else that healthy soil can do.
Another important metric in this is the water holding capacity. One great benefit to improving soil health resides in its relationship between organic carbon and the soil’s capacity to hold available water.
For example, researchers have found that a one gram increase in soil organic carbon increases available water by one to 4.9 grams for every 100 grams of soil. Increasing soil organic carbon is clearly shown to increase available water holding capacity, which benefits plants and animals up and down the food chain.
Tying it all together, lack of soil biodiversity can be caused by many issues and it creates less holding capacity, which ultimately makes water runoff at higher rates than it otherwise would. More runoff erosion, more water contamination from chemical inputs, more topsoil loss. And the cycle just continues to accelerate.