Soil degradation

Soil degradation might not be the first environmental issue that comes to mind but it should.

More than half the agricultural soils around the world are less productive than they once were and the FAO [Food and Agriculture Organisation] estimates that globally 15.8 million km2 of land is are affected by erosion or is degraded through physical/chemical action.

15.8 million km2 is roughly 10% of the global land area — not much perhaps. Except that not all land on the globe can be used for plant production.

Currently we are able to use roughly 33% of the total or 48.9 million km2 for agriculture [arable, permanent crops, and permanent pasture].

15.8 million is a much larger percentage of the land area we actually use for production.

The specifics of the numbers are not all that important, the environmental issue is that the proportions are so high.

We already use a lot of land and a lot of that already has soil degradation or at risk.

Food production must double

Then there is the scary notion that global population growth and increased affluence sought by the existing 7 billion souls will mean that food production will have to double in the next 30 years.

By 2030 global food production will need to be around 8 billion tons per year and stay at least at this level each and every year for many decades before demand falls 

A doubling of food production sounds challenging until you consider that we have doubled production a few times already.  Initially it happened with mechanization, then the green revolution and latterly technology driven intensification.

We have already appropriated all the good land, learnt how to rely on energy and nutrient inputs, and used genetics to our advantage. Finding improvements to a system that is already heavily-dependent on fossil fuels, inorganic fertilizers, pesticides, herbicides and industrial scale production, not to mention that we use much of the easily available freshwater for irrigation, starts to sound insurmountable. 

There will be aquaculture, aquaponics, rooftop gardens and any number of technology solutions to cover some of this production, but soil will be the medium to grow most of the food we need.

We will always rely on soil as the medium to deliver plant growth rather than just a place in which roots sit to receive the nutrients we add to it.

We will need ever acre of soil in its best condition to double production and keep producing at that level for several decades while the population bulge passes.

Soil as a resource

Soil is our most valuable resource.

Only rather than look after it as natural capital that is not renewable in our lifetimes, we tend to:

  • mine soil nutrients
  • allow soil carbon to decline
  • forget to cover the ground with cover crops that protect against wind and water erosion
  • use machinery and hard hooved animals on soft friable soil
  • plough to make everything homogeneous
  • use inorganic fertilizer to try and replace what was lost

Of course there are many farmers who do not do these things. It is possible to use minimum tillage, use cover crops wisely, encourage sole carbon buildup, use time grazing, manage water use and a host of crop and livestock approaches that reduce the impact of agricultural practices to limit or even avoid soil degradation.

But the pervasiveness of environmental issue suggests that these practitioners are in the minority and mostly we do not do these things.

Instead we treat soil and the plant and animal production and supplies as a free good that is renewable indefinitely.

An important Ask Alloporus learning is that ‘free’ goods and services are rarely free.

This is increasingly the case with soils. As soils degrade so producing crops or livestock becomes less profitable, sometimes to the point of being marginal. What was once free can become costly to maintain.

We can see this change by measuring soil organic matter [SOM]. This is the carbon in soils that comes from humus, roots, microbes and fungi and is the material that gives soil structure and vitality, ultimately the key factor in plant production.

When soil is at or near its SOM capacity, from the plant growth perspective, it has better structure, accepts and retains moisture, exchanges nutrients and is a better place to be for seeds and seedlings compared to the same soil with low SOM.

Only this is what usually happens when the use of agriculture — in this case for sheep and cattle grazing in Australia

It is possible to reverse this pattern of SOM decline

Some good news

Unlike some environmental issues soil degradation can be reversed. It is one environmental issue that we could cross off the list.

Careful land manager can return structure, organic matter and nutrients to soils.  And in the right conditions this does not have to take forever.

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understanding soil properties requires extensive sampling

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