Building Soils to Save the Planet

Last year when I was reading through the Scientific Amercian Articles about Climate Change Solutions, and again in Al Gore’s Inconvenient Truth, I was stunned by the carbon emissions from agriculture. I understood the simple logic of the implications with cutting/burning trees for ag land, but they were referring to regular existing Ag Land. After mulling it over while reading/watching, I got distracted and never really gave it much more thought.

Now I am reading more books about soil fertility, and other tid bits of info are coming back to me. Like I read somewhere that most depleted soils worldwide are carbon, not nitrogen limited as most commonly thought. And then there is the carbon sequestration aspects that are mentioned in the arguments for Switchgrass Ethanol. In Building Soils for Better Crops, the authors mix in alot of sustainability into their soil talk- no aspect of our lives can afford to be treated in a vacuum. Part of that is getting more in detail about the placement of soils in the Global Carbon Cycle.

According to the authors, there is more carbon stored in soil (soil will mean the top 6″ in this post), than in all plants, animals, and the atmosphere. They make a great example that makes is very accessible: there is as much carbon in a soil with 1% organic matter than there is in the entire atmosphere above that acre. There is about 2,000,000 pounds of soil in the top 6″ of an acre, so 1% of that is about 10 tons. Here is the kicker, most soil on undisturbed Prairie had organic matter in the 10-12% range. After a century of tilling it is down to about 2%. The authors don’t do this math, but to me, it is a safe assumption that for every acre of prairie “busted” in the last century we put 90 tons of carbon into the air. We have 349,000,000 acres of crop land, using the math ( I realize we are compounding any errors in the earlier examples but focus on scale not specifics) we have emitted 31,410,000,000 tons of carbon just from Ag Land. This is where the despair comes in.

I hate despair. I don’t have time to be depressed, so I immediately start looking for solutions. That incredibly daunting math in the above paragraph can work in reverse. While Big Coal panders about trying to find way to sequester carbon from their electric plants with some other Huge Industrial Idea, Nature has already created a perfect system: in her own plants.

This is where it gets exciting for me. Our cropland is currently near death and on chemical life support, primarily due to the lack of organic materials in the soils. For every 1% of organic material we add back into an acre of soil we save 10 tons of Carbon, while also significantly increasing the productivity of the land for food production. And the best ways to get organic material back into the land? Sustainable Ag practices: crop rotations with sod forming cover crops, reduced tilling, composting, and applications of animal manures instead of nitrogen derived from natural gas. Basically turn the clock back 60 years and call a “Do Over”.

I’ve read that if we converted every farm east of the Missouri River to the farming practices of Joel Salatin we would remove as much carbon as we emit every year. That seems a little far fetched, but it is safe to say we have at our finger tips the ability to significantly increase the quality and quantity of our food production while simultaneously reducing our Carbon emissions to a huge degree.

Maybe all the answers to life can be found in a Garden!


One Response

  1. […] like this.  Written by Rob over at OneStraw, it is part of a piece about soil fertility and how much carbon is (potentially) stored in […]

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