Soil Erosion
I was talking to Professor John Crawford from the University
of Sydney about the subject of soil erosion this week. John is doing a lot of
research into the global soil erosion issue (he is Head of Sustainability and
Complex Systems at the University) and he commented recently that “A broken
food system is destroying the soil and fuelling health crises as well as
conflicts.”
I ask him if he thinks that soil is really running out
around the world.
John thinks that we are on borrowed time. “A rough calculation of current rates of soil
degradation suggests we have about 60 years of topsoil left”. He says. Soil is
being lost at between 10 and 40 times the rate at which it can be naturally
replenished. “
John continues to tell me about why these issues are not
publicised. “The connections to health,
the environment, security, climate, water are not always made clear. For
example, agriculture accounts for 70% of our fresh water use. We pour most of
our water straight onto the ground. If soil is not fit for purpose, that water
will be wasted because it washes right through degraded soil and past the root
system.” John continues to tell me more
about the soil. “Soil is a living material: if you hold a handful of it, there
will be more microorganisms in there than the number of people who have ever
lived on the planet. These microbes recycle organic material, which underpins
the cycle of life on Earth, and also engineer the soil on a tiny level to make
it more resilient and better at holding onto water.” He tells me enthusiastically. “Microbes need carbon for food, but carbon is
being lost from the soil in a number of ways.
- We take too much from the soil and don’t put enough back. Whereas the classic approach would have been to leave stubble in the field after harvest, this is now often being burned off, which can make it easier to grow the next crop; or it’s being removed and used for animal feed.
- Carbon is lost by too much disturbance of the soil by over-ploughing and by the misuse of certain fertilisers.
- Then there is overgrazing. If there are too many animals, they eat all the plant growth, and one of the most important ways of getting carbon into the soil is through photosynthesis.”
Key Issues
Societies in the past had collapsed or disappeared because
of soil problems. Easter Island in the Pacific was a famous example. Ninety per
cent of the people died because of deforestation, erosion and soil depletion. Iceland
is another example where about 50% of the soil ended up in the sea. Icelandic
society survived only through a drastically lower standard of living. I ask
John what issues are not being addressed.
“There are two key issues.
- Loss of soil productivity; degraded soil will mean that we will produce 30% less food over the next 20-50 years. This is against a background of projected demand requiring us to grow 50% more food, as the population grows and countries eat more meat.
- Water will reach a crisis point. This issue is already causing conflicts in India, China, Pakistan and the Middle East. Before climate change and food security really hit, the next wars are likely to be fought over unsustainable irrigation. A staggering paper was published recently indicating that nearly half of the sea level rise since 1960 is due to irrigation water flowing straight past the crops and washing out to sea.”
Soil erosion is most serious in China, Africa, India and
parts of South America. If the food supply goes down, then, obviously, the
price goes up. The crisis points will hit the poorest countries hardest.
Food Quality
I’m interested to see what John has to say about food
quality.
“The time of economic difficulty in the West is causing a
growing disparity across society. The connection here with health is
significant. Cheap food tends to be low in protein and high in carbohydrates,
which is exactly the wrong balance. By reducing food to a mere commodity, we
have created a system that is degrading the global capacity to continue to
produce food and fuelling a global epidemic of diabetes and related chronic disease.
We’re subsidising unsustainable food production systems at the cost of our
health and our environment.”
John tells me more about how soil isn’t costed into food
prices.
“Farmers don’t have the financial capacity to invest in
their soil to turn the situation around. Modern wheat varieties, for example,
have half the micronutrients of older strains, and it’s pretty much the same
for fruit and vegetables. The focus has been on breeding high-yield crops that
can survive on degraded soil, so it’s hardly surprising that 60% of the world’s
population is deficient in nutrients like iron.
If it’s not in the
soil, it’s not in our food.”
I ask John if he has any idea how the situation can be
improved. “Significant progress is technically quite straightforward. There’s a
lot we can do, we just have to choose to do it and provide the right support
where it is needed. We can:
- Focus on getting carbon back into the soil by reversing bad farming practices like tillage, nutrient mismanagement, removing stubble and over-grazing.
- We can add manure and consider using human waste from cities as fertilizer, instead of just flushing it out to sea.
- In the longer term, breeding targets need to focus more on human nutrition as well as productivity, and on traits that improve the soil.
- We need to find new ways of bringing together scientists and farmers to harness the expertise of both.
- From a policy standpoint, probably the most important thing is to find pricing mechanisms that take into account the environmental, health and other costs of a broken system.
- Farmers need to be appropriately rewarded for regenerating the environment and producing food that supports a healthier society.
- Finally we need to recognise that this is a global problem that would benefit from a global approach. We don’t need to reinvent the wheel in each country, and we don’t have time to do so. It takes decades to regenerate soil.”
And as John said at the beginning of the interview, we are
on borrowed time.
