Sunday, 29 March 2015

Hey man! I really dig that earth!

Soil is a living, breathing organism - an amazing habitat!
Soil is amazing stuff – if we allow it to be!

A really top quality arable soil is made up of, perhaps somewhat surprisingly, 25% air, 25% water, 45% minerals and around 5% organic matter, with the organic content potentially rising to around 10% when under permanent grassland and therefore not cultivated.

One single teaspoon full of healthy soil contains around 1 billion bacteria, meaning that a handful of soil has more living organisms within it than there are people living on planet Earth! 
One of the primary purposes of soil bacteria lies in its role in decomposition, which is a vital process within the ecosystem, because nutrients trapped in plant or animal tissue are broken down and made available to other organisms. This process ensures the recycling of materials within the soil and for instance, plays an integral role in the nitrogen cycle. Organisms are unable to use nitrogen in its gaseous form, however bacteria in the soil will fix nitrogen from the air so that plants can use it.

Earthworms also play an important role by eating organic matter and breaking it down into smaller pieces allowing bacteria and also fungi to feed on it and release the nutrients. Charles Darwin referred to earthworms as ‘nature’s ploughs’ because of this mixing of soil and organic matter.

Talking of fungi, it is thought that over 30% of the sugars produced by the plant are released through the root system to feed the soil biology and maintain the ecosystem around the plant. The release of sugars forms the basis of a symbiotic relationship, as these sugars in the soil enable the microbial populations to multiply around the plant roots. 

A fairly recent discovery is that Mycorrhizal fungi also produce a sticky substance known as glomalin, which has been referred to as “soil glue”. Combined with the fungal ropes, which are the strands produced by the fungi to absorb nutrients, this glue is responsible for building soil structure effectively binding minute soil particles together to create soil crumbs, which helps to prevent soil from slumping and eroding.

Now for a truly staggering statistic. The main body of most fungi is made up of fine, branching, and mainly colourless threads called hyphae. Each fungus will have vast numbers of these hyphae, all intertwining to make up a tangled web called the mycelium. In arable soils you might expect to find between 1 & 2 metres of these fungal threads in every gram of soil, which rises to a 100 metres or so in soils under permanent grassland. But wait for it, if you think that is amazing – the fungal threads in an ounce of soil taken from the forest floor can be as long as 40 miles in length!! 
There is increasing evidence that the poor condition of many soils, which lack a thriving “biology” are contributing to a build-up of locked nutrients, with only 5-10% of all inputs ever reaching the plants they were intended to support. Add to this the removal of many crop protection inputs, and world phosphorus reserves coming under strain in the coming decades, those with an eye on the strategic nature of farming are once again looking at how to harness soil biology to unlock bound macro elements, increase nutrient availability and thus reduce artificial inputs on a commercial scale.

However, we must also make sure that our soils remain where they should be – in the field.

Government research is showing that through soil erosion we are losing 0.1 - 0.3t/ha of top soil annually and it is the most fertile soil which is lost first. This equates to an annual loss in the UK of 2.2 million tonnes of soil through erosion (Parliamentary Office of Science and Technology). Oh, and by the way, it takes approximately 500 years to replace 1 inch of topsoil lost to erosion.

So, as the UN General Assembly has declared 2015 as the "International year of soils", perhaps now is the time to start looking after our soils much better than we are currently, and indeed many farmers are now focussing on just this matter with some urgency.

I think that it might help if we can all begin to think of soil as a living and breathing organism – a habitat that is as packed with biodiversity as any top notch, designated nature reserve. Then we might tend it with more care. 

One final thought - If you imagine our planet began as a single day:
Microbes appeared at 5am
Dinosaurs appeared at 10pm
... and humans appeared seconds before midnight.

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