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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Science of Sustainability- Preventing Soil Erosion On Your Land

If you wish to build a sustainable homestead then it is critical that you know how to control soil erosion in all its forms.  Just a quick recap if you didn't read my last post soil erosion is caused by wind and water moving the soil from one place to another.  It will depend on your location and management practices which type of erosion is more devastating to your land.

If you live in high wind and dry areas like the Great Plains of America then wind is your primary concern as it can take exposed soil and carry it off .  During the Dust Bowl areas that were hit hard by it lost over 5 inches of topsoil by 1938.  When it takes 1000 years to form a inch of soil losing 5 inches can be devastating to local ecosystems and agriculture.

But back to the focus of this post which is preventing soil erosion from happening.  The method to prevent soil erosion is a simple idea on paper but can be hard to do in reality.

Soil doesn't like to be naked...

This make look trashy but I'm actually helping my soil.

What I mean by that is that if you want your soil to perform at its best in all conditions it needs to be covered by a protective coating of organic matter.  It prefers to have living perennial biomass like grasses but it will take whatever it can get.  So if you want to prevent soil erosion from both wind and water keep your soil covered with some sort of vegetation.

It works on both because wind and water move in the same way as described by a branch of physics called fluid dynamics.  As wind and water hit obstructions on the soil i.e plant matter it slows them down.  The slower the movement, the less erosive power the wind or water has.  It is relatively easy to keep all your garden beds covered with plants or a mulch layer but when you start dealing with farm size agriculture then it gets trickier.  The best thing you can do is minimize tillage of the fields or go no-till and leave as much organic matter on the field as possible.

The nice thing about keeping soil covered is that when it does start to move it will get stopped and dropped back to the soil surface as it runs into plant matter.  So technically soil will be moving around on the field but it won't get very far because every direction it goes it runs into something.

But keeping everything covered in plant matter is only part of the battle you also have to plan according to local topography, climate and soil class

You don't want to garden on slopes as they just give water a running start on eroding away your soil.  You get one bad rainstorm and you will watch your garden wash away.  You can mitigate this issue by building terraces on sloped fields which reduce the steepness of the slope.  But if you can avoid exposing soil on slopes I would recommend it.

You soil class is also key to fighting erosion.  Some soils are more likely to erode then others and knowing your soil and its erosive potential can save you a lot of headache.  To learn more about your soils erosive potential do a texture test on it to figure out what class of soil it is,

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