Science of Sustainability- Why is Soil Organic Matter Important?

Organic matter is a essential part of soil that gets overlooked in many conversations about soil. While most people will be talking about soil pH balance, its composition or how well it grows crops they will leave out organic matter.

This is a mistake.

Home compost a.k.a organic matter

Organic matter when you get right down to it is one of the most important parts of the soil when it comes to doing what soil does best and that is grow things.  Now when soil is first formed it has no organic matter as it form out of a rocky parent material that has been broken down.  But as you get the first hardy inhabitants like lichens they begin the process of adding organic matter to the soil.  Time goes by and the lichen give way to grasses, trees and forests as the soil builds up over the millennium.  All this organic matter is what makes soil useful to us.  Without it, it will be impossible to grow the food we need.

A easy definition of organic matter is any living or dead material that is either incorporated or is on top of the soil.  A continuous organic matter supply is critical for soil to function in a sustainable fashion.  It has a few key functions that allow for soil to be fertile over the long term,

1. Acts as a nutrient sink.
2. Retains water
3. Provides food for soil organisms.  

Nutrient Sink

Everything living thing is a storehouse of nutrients/energy that we have borrowed from the Earth and the Sun.  When a organism dies the nutrients that are tied up the body get released into the environment to be used by something else.  It is the ultimate form of recycling with nothing going to waste.  Now as something decomposes it adds decayed organic matter to the soil which are essentially little nuggets of plant available nutrients just waiting to be used again.  That's why when you add compost a.k.a decomposed organic matter to a garden the crop you plant there does better than if you hadn't added any.  The higher the the percentage of organic matter in the soil the more fertile the soil is.

Retains Water 

While I cannot give you exact numbers on how much water since it changes from place to place I can tell you its a lot.  The organic matter essentially acts like a giant sponge absorbing and releasing water at a slow place just as the plants need it.  If you have a healthy soil with lots of organic matter it can absorb higher amounts of rainfall before the soil becomes saturated.  This leads to lower erosion and better yields from crops because the plants have a steady water supply.

Food for Soil Organisms   

Worms, bacteria and fungi need to eat to,  When they eat the dead organic matter they break it down even faster and concentrate the nutrients even more.  You may have seen or heard of worm bins which are worm powered composters which can eat up to half their weight in food a day and produce incredible compost.  The organic matter is essential food for soil organisms and with enough organic matter you will have a lots of them improving your soil.  

So take away points from this is that organic matter is important and maintaining and adding to it should be a goal of any person interested in sustainable/green living.

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