Carbon Capture, Science hacks

Soil Testing for Science Hacks – Part II: The Number

Soil Drainage Test
Testing your soil’s drainage is easy to do.

After a long wait, my Year 1 soil test results are in. Note: although there are some great soil tests you can do yourself – see the pictures in this post – the soil test results I will now share are from Colorado State University’s Soil, Water and Plant testing Laboratory.

All of the researching, sampling, mailing and waiting while CSU did their thing has yielded up one precious number (and lots of other numbers I don’t care about as much). And it is . . . 1.7%!

One point seven percent of my soil is the sum of my Soil Organic Matter (SOM).

What the heck does that mean? Well that is where science hacks really have to earn their keep. It doesn’t mean anything really, unless you put it in context. Putting it in context kept me and my Scientific Research class at Amy Biehl High School busy for a couple of weeks (we only meet for an hour and a half a week though). A report of our findings follows.

But first and most importantly, 1.7 percent is my baseline – my starting point, the number against which I will measure my success. Like an inverted diet, I will now try to gain as much organic matter (in my soil) as I can. The higher my SOM the better! Five percent or bust!

Now for the context. Healthy garden soil that holds lots of water and supports lots of tender annual plants, has 4 to 6 percent total organic matter according to one source and up to 15% according to another. So clearly I have a way to go. The question I asked my class has to do with whether it really matters if I do get there:

Assuming that the average organic matter content in Albuquerque soils is 1.5%, how much carbon could be sequestered if all Albuquerque soils were improved to a 3% or 4.5% total organic matter? 

We had to work pretty hard to try and answer that question. There were many many unit conversions. We had to learn about bulk density of soils, the amount of actual carbon contained in that organic matter, the depth of soil we were talking about (the top eight inches, we decided, since that is what I had tested at the Mothership), and of course the area of Albuquerque. We assumed 50 percent of the area of Albuquerque was hardscape (buildings, roads, parking lots, and so forth), an estimate I had seen recently. We used 1.5% as our baseline because we assumed that the average soil here is a little lower than my baseline, and 1.5 is an easy number to work with.

Soil Texture Test
Another easy test is for soil texture. It is usually called the ribbon test.
Soil Texture "Ribbon"
When you form the “ribbon,” the frequency of breaks tells you the texture

And in the end, I had a bunch of really tired looking students, and I think a pretty solid answer to the question. If all the soils of Albuquerque increased their Total Organic Matter from 1.5 percent to 4.5%,  1.12 million metric tons of carbon would have been sequestered.

To put this in perspective, the average American emits around 19.8 tons of carbon per year. So if we increased the soil carbon content in Albuquerque to 4.5% it would cancel out carbon emissions for 56,781.5 people for one year. The population of Albuquerque is 559,374. So it would cancel out the carbon footprint of about 10% of the population for one year. 

Is that underwhelming, or is it just me? I mean I knew that just changing our yards wouldn’t totally solve the climate change problem – but I was looking for a little bit bigger boost. But here is the thing. There is something in permaculture called value stacking. You do one thing that solves three problems. When you begin to “see” the carbon cycle and your place in it, your understanding of how to tackle climate change really changes. And you are soon seeing stacking functions all over the place.

Here is an example: as you increase the carbon content of your soil, your apple tree grows really well, and produces more tasty apples. This reduces the number of apples you import from elsewhere, further reducing your carbon footprint. And maybe you even find yourself happy staying home just a little bit more this year, pruning your apple tree and picking your apples rather than maybe going out to a restaurant or driving around doing the shopping.  A tiny bit more carbon footprint reduced. Inspired by your own actions you make other carbon sequestering choices, like deciding to commute on an electric bike or by bus instead of by car. Inspired by your own actions, you inspire others. Soon we are really owning our climate problem.

Besides the function stacking effect, it’s clear that at some point we will all need to turn our newly carbon aware gazes to the wider landscape. New Mexico has a vast land area, and most of its soils have been slowly decarbonizing since European settlement. The soils hold less and less water, and less and less organic matter, as our land practices continue to have effect – grazing practices (though grazing in itself is beneficial with the right management), forestry practices (especially deforestation and fire suppression) and water management practices (especially flood control and beaver eradication). Once you know what you are looking for, it’s shocking to see how degraded our landscape is becoming. And this is true all over the arid west. Even well intentioned land owners rarely have carbon aware gazes these days, and there is a lot of educating to do. Deeper and deeper arroyos flanked by high and dry junipers growing on bare mineral soil don’t yet inspire action in our citizens – but they need to! Land restoration is possible, and it goes hand in hand with both carbon sequestration and more water in the landscape. Land restoration on a larger scale also means carbon sequestration on a larger scale, and then climate stabilization is around the corner!

Get your soil tested to find your baseline carbon content!


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11 thoughts on “Soil Testing for Science Hacks – Part II: The Number

  1. I absolutely love this post. My eyes have been opened in so many ways by your blog. When I go running in my arid desert landscape, I see all kinds of things that could be tended to which could increase the level of organic matter in the soil, allowing our scant and infrequent rain water to better absorb into the ground. Today, it occurred to me that the native locust trees that are sprouting in my back yard could be potted, and planted along the creeks that flow about a half mile above our house, before they empty into the Los Angeles Department of Water and Power’s aqueduct. Just adding trees to the “living sponges” on the sides of the creek would help to hold more water in the landscape. Also, I am going to look into leasing the DWP (department of water and power) land behind my house, and replant the dead landscape with wild rose bushes, and other native plants which will help build the soil. Small steps, but who knows the larger consequences. I will keep you posted!

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