This pages looks at how nature creates soil


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How nature makes soils

Regenerating soil

rhizoshereWhere to start? Well nature has been making soil for a few billion years so let us see what we can learn by taking a trip from the equator to the poles.


The equatorial zone

equitorialregion.jpgDespite the fact that equatorial soil gives the impression of being rich they are really very poor. The apparent luxuriance is caused by the continuous humidity which enables plants to feed of the dead vegetation in real time as it decomposes. Any nutrients which are not immediately recycled are simple swept away by the heavy rain.

The monsoonal belt

monsoonalbelt.jpgMoving away from the equator we enter the dry winters and monsoonal rains. Soil does develop in the warm winters but there is significant loss of soil in the heavy rains.

Too much rain is not good.

The desert regions

desertrgeion.jpgMoving poleward we enter the desert regions with no reliable rainfall. At first sight there does not seem to be much soil at all, just bare sand but anyone who has been to the desert after the rare rain will be impressed by the mass of vegetation which appears virtually overnight and disappears in a few weeks.

Water is essential for soil formation but life can survive for years of drought.

You don’t need to be an expert in thermodynamics to drive a car

The lesson here is that seeds, soils biology (and even the desert frog which wraps itself in its own waterproof bag) can survive for years in dry conditions. As I learned regenerating soil is dominated by soil biology - which is incredibly complex. We have only discovered a small proportion of the species and it will be a long time before we have a true understanding.

We don’t need to understand everything - we just need to know how to care for the soil biology so it can do its job. After all we have no idea how to create life from scratch but we have still created hundreds of billions of people over time by following our natural instincts (or lust).

The rich Savanah belt

savanah beltNow we enter the Savanah zones which spread around the world in both hemispheres. Often there is rich soil - tens of metres deep. This is where much of the world’s food is produced and man has to work pretty hard to destroy this rich top soil - yet it happens - as in the great dust bowl in the US.

We can also see that even in the rich Savanah lands that some areas have much better soil than others. This coincides with regions where the base rocks are volcanic and rich in a broad spectrum of minerals.

The Tundra

tundra.jpgAs we get nearer the poles there is still vegetation but typically a monoculture of specialist plants which can survive the extreme conditions but the dead plants turn into peat rather than soil.

How soil is created

Soil formation requires the right amount of water and a broad spectrum mineral base - nothing surprising here.

Modern science has an extremely good understanding of the mineral needed to make soil, the chemistry is a done deal - but there is more to soil that just chemistry - the physical form or structure - of the soil is equally essential.

So let’s study how soil is formed particularly learning from the Savanah regions.

soil creation To my mind one of the most important symbiotic relations in the world is that between plants and soil biology.

The plants, by photosynthesis, produce an abundant supply of carbohydrates which they feed to the soil biology as either exudates or simply by the decay of dead vegetation. In return the soil biology creates enzymes which dissolve the rock making nutrients available to the plants; they also provide the glue which creates the aggregates which makes the texture of a good soil.
Soil is created by biology

Lava flows

lava.jpgA particularly interesting subject is how lava flows are converted to soil.

Lava is full of minerals but there is a catch 22.  Fungi cannot photosynthesis so cannot survive without the energy from plants to break down lava - they need plants.  But plants cannot break down lava without fungi.

lichen.jpgLichens are peculiar organisms - neither plants nor fungi - but able to do the job of both.

A lichen is a composite organism that arises from algae or cyanobacteria (or both) living among filaments of a fungus in a symbiotic relationship.

Lichens can get the process going by breaking down the rock surface.  This allows the weeds with strong tap roots to start colonizing.

Weeds are often short lived and so a compost forms form the dead plants.  This allows plants with a more fibrous root structure which form a synergistic relationship with mycorrhizal to become established and in a relatively short time some of the worlds most fertile soil has been produced.

Plant roots, particularly the tap root of weeds provide a service by creating channels through the soil connecting the surface to the lower layers,  essential for 'breathing' the soil.

When the plant dies the roots rot automatically creating channels.

Pretty neat stuff this nature.

Soil biology is complex –

we need to learn how to ‘farm’ soil biology

Anyone who studies soil biology appreciates how little we really understand this complex subject. On the other hand we don’t need to understand every intricate detail. I contrast creating soil by using biology with baking a cake.

soilformation.jpgA good cook can make a delicious cake by following the recipe but may not understand the chemistry. The same with soil, we now have the recipe to create a healthy soil as yet we may not understand the mechanics of how the soil biology is generating the soil but by creating the conditions for the biology to flourish we can produce a healthy soil.

Soil needs a better PR agent

So why are will still destroying soil on such a massive scale? It is partly because soil has never captured the public imagination like a new i-Phone with an updated version of Angry Birds but the core reason is simply that modern chemical farming is more productive - as measured by the quantity of food produced - than soils produced by this natural process.

You don’t need soil to produce good looking plants - just take a bit of sand to hold up the plants and add chemicals and plants will grow.

I sometimes think that my passion for soil came from a false Eureka moment - you simply don’t need soil to produce food.

This is where the catch comes - the food may be full of energy but lacks the critical trace minerals, vitamins and phytonutrients which are needed to rebuild our bodies.

This is often referred to as empty calories.


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How nature makes soils