I know that blog posts are supposed to be positive and uplifting—so click away now because this one is a real Debbie downer.
Rather than sugarcoat, we have a pragmatic statement of the facts because, as the motto of the University of Botswana says in the Setswana language Thuto Ke Thebe or in English, ‘education is a shield’.
So read on to realise that knowledge brings power.
We start with a series of observational and experimental facts collated from the scientific literature by researchers from the UK, Brazil and Poland
- In the last 150 years, more than half of all soils have been damaged
- Degradation of soil has been accompanied by the loss of more than 50% of the soil organic carbon (SOC) stock in some cultivated soils, with over 2 billion ha affected globally
- Soils subjected to degradation become a significant emission source of CO2 to the atmosphere and have liberated an estimated 176 Gt of soil carbon globally—there is 800 Gt C held in the atmosphere
- Averaged over the last 150 years, the soil carbon loss rate equates to 1.6 ± 0.8 Gt C yr−1 compared to total anthropogenic global carbon emissions estimated to be 7.5 Gt C yr−1
- Agriculture, forestry and land use change is reported to be directly responsible for approximately 18–24% of total anthropogenic GHG emission each year
- Conversion of natural ecosystems to managed systems is reported to deplete SOC stocks by an average of 60% in temperate regions, and up to 75% in the worst affected regions of the tropics, accounting for losses of up to 80 t C ha−1.
This is huge.
It contributes to the current rapid climate change and what could be done to mitigate further change.
The impact of soil degradation on climate change is dramatic, but it’s not even the most critical issue. That honour goes to the consequences for soil function of losing carbon.
Here is a general list of what happens when soil is depleted in organic carbon.
- reduced nutrient provision
- water retention and availability declines
- loss of below- and above-ground biodiversity
- soils become more vulnerable to erosion
- accelerated processes of desertification in drier regions
- decrease in crop yields
Alright, Debbie, that is enough. We get it. Soils can be damaged, and when they are, they lose carbon which is not good.
But wait, there is more.
Soil resources, although abundant and long-lasting, are non-renewable on a human (anthropogenic) timescale. If soils are damaged, they take time to recover. And if the soil is lost through erosion, it can take millennia to replace.
Consequently, poor soil management and loss of soil carbon
- have exacerbated topsoil losses to 10–40 times greater than natural replacement rates—in the USA, topsoil loss rates are roughly 10 times that of replacement; while in India and China, loss rates exceed 30–40 times natural replacement
- impairs society’s ability to grow sufficient crops
- decrease crop productivity by 0.3% per year, expected to aggregate to an average of 10% reduction in yields by 2050
- across the European Union, 45% of agricultural soils are considered impaired or very impaired in SOC content
It is tempting to gather all this bad news and describe it as a financial cost. Here is what the researchers estimate.
- the cost of soil degradation in the EU exceeds €38 billion yr−1, with associated crop loss costing more than €1.25 billion yr−1
- in the USA, soil degradation and reductions in soil carbon are estimated to cost at least US $44 billion yr−1
- globally, the effects of soil degradation compound to a total estimated cost of approximately US $300 billion each year
The problem is that these costs are not on the books of the farmers or the various players in the food supply chain. They are in the future and are only ever recorded as opportunity costs that rarely, if ever, appear on balance sheets.
This is a problem that faces all natural resource use.
If a cost is not booked, then the business looks healthier for a time. The problem of damaged soil with depleted function and ongoing degradation is kicked down the road for a balance sheet in the future. Making money today always wins over money made in the future, significantly if that future profit is compromised by today’s externalities.
This is how humans have always used resources. Benefit today, worry about the future later and let nature absorb the externalities.
Only soil is the fundamental natural resource essential to human survival; without it, we starve.
What sustainably FED suggests
If you are worried by these numbers, you should be. This is some very scary shit.
Soil degradation is not the only grand challenge for society; it might not even be the most immediate. It certainly has one of the lowest public profiles, easily overshadowed by the cost of living, energy crises, climate catastrophes, and war.
But ignore the research evidence in this post at your peril.
Talk about it with your friends and ensure it gets onto your list of issues come election time. Because even if you live in a country where supermarket shelves are stocked, and the family food budget is less than 20% of disposable income, not every human is so blessed.
Hundreds of millions and soon-to-be billions of people are exposed to the food supply consequences of degraded soils, and they will move to find food.
It could get ugly.
We owe it to them and ourselves to reverse the damage to soils and ensure there is enough food for everyone for a long time.
Keenor, S. G., Rodrigues, A. F., Mao, L., Latawiec, A. E., Harwood, A. R., & Reid, B. J. (2021). Capturing a soil carbon economy. Royal Society open science, 8(4), 202305.