Welcome back. To recap, last week I shared a bit of my experience and knowledge base as it relates to renewable forms of energy, organic urban farming, ecology, and social influences on these subjects. Today I want to share what I know about dirt, specifically soil and why dirt is not soil, why that's an important distinction to make, and why soil is so important for all terrestrial life. I'm going to cover in brief the current state of soils worldwide and the effects soil health has on global warming, water availability, and regional climate stability. Because this is a dense topic and even with simplifying most of its content this blog will run long, I'm splitting it in half and next week I'll cover the most effective, simple, and easy things that everyone, regardless of income or resources, can and should do to build soils.
While I believe most everybody knows that in general things are not looking good for our planet and our species and that our future is bleak, I believe most people willfully look away from the problem because it's so overwhelming and it's easier to not face reality, this is a form of cognitive dissonance. If this is you don't feel ashamed, like any skill it takes time to develop the ability to face these kinds of problems on a daily basis and take action in spite of the overwhelming feelings they generate. Some of the following paragraphs are grim and spell out our future in no uncertain terms, however I don't care for shock doctrine and fear mongering. My intent here is to educate, offer simple solutions, and inspire you to take action. With this in mind, lets begin.
Soil is a living organism. While there is no scientific founding to that statement, as in it is my belief and not necessarily fact, it's accurate to say soil is biological organic matter comprised of and home to an incalculable number of biological organisms that by their presence or absence determine soil health and viability. Dirt on the other hand is not alive and does not support life. Comprised of inorganic mineral compounds, dirt is inert. Rhyme intended a as mnemonic device to help remember why dirt, though a component of soil, is not soil. The reverse however is true, soil is a form of dirt. This is an important point to make because without adequate water in the form of moisture and without a healthy and diverse community of soil biota, soil rich in organic matter is just dirt and dirt cannot support complex forms of life, where soil can and inevitably will.
SOIL.
Photo credit: http://www.radionz.co.nz/national/programmes/ourchangingworld/20141030
DIRT.
Photo credit: http://www.huffingtonpost.com/2013/01/22/ne-quittez-pas-dirt-menu_n_2526088.html
Plants are primary producers. This means that plants take inorganic compounds (dirt) and convert them into organic compounds, most often by means of photosynthesis. However, it's not exactly that simple. If it were, there would be no deserts because plants of all kinds could and would establish themselves and convert lifeless desert expanses into lush paradises without much effort. One of the keys to making it possible for plants to establish and flourish, especially more complex and food producing plants, is a bare minimum of three percent organic matter in the soil and the accompanying soil biota that make soil and facilitate nutrient cycling. Another key to healthy viable soils is moisture, which is held in the soil by both high levels of organic matter and a complex community of soil organism. If soil moisture is depleted, then biota die off and soil formation and nutrient cycling slow, then less or no plant life can survive. If organic matter is depleted, then less moisture can be held in the soil and soil biota die off, then nutrient cycling and soil formation slow or stop and almost no plant life can survive without irrigation and fertilization. If biota are killed off, then soil formation slows or stops, nutrient cycling stops, pathogens and disease rise in number and plant life can only survive with added fertilizers, pesticides, and fungicides while no new healthy beneficial biota can establish because chemicals meant to kill pathogenic life forms also effectively kill off the beneficials. I hope you are starting to see the connectivity and cyclicity here. Everything stems from healthy soil.
In the U.S. alone, since the 1950's we have depleted some thirty percent of our arable soils to less than one percent organic matter and of the seventy percent left, seventy percent of those are expected to be depleted of organic matter by the year 2100. Even more alarming, this trend is closely mirrored worldwide. That is to say most of the world will be without arable land within the next seventy to ninety years. This is not even considering rates of erosion from over plowing fields, soil salinization and water depletion from poor irrigation practices, and expanding desertification from overgrazing and global warming. To add perspective, it takes natural processes thousands to tens of thousands of years to develop just one inch (2.5cm) of soil and to sustain intensive agriculture a minimum of one foot (30cm) of soil is needed. The sobering reality is that by 2050 most parts of the planet, including the U.S., will not be able to supply the food necessary to support our population as it exists today, let alone the projected population of ten billion people. To put the timeline in perspective I'll only be 65 and my kids late 20s to early 30s. What age will you be?
The dust bowl will become a worldwide phenomena.
Photo credit: http://kansaspublicradio.org/kpr-news/pbs-air-ken-burns-documentary-dust-bowl
Are you ready for the rabbit hole to get deeper? There is a way out, its not all doom and gloom, I promise. Remember, the solutions are rather simple and easy to do. We'll get to that next week, but first lets take a look at how soil health relates to global warming, water availability, and regional climate stability.
Organic matter in soil equals carbon in the soil and carbon tends to stay locked up in the soil for thousands or even millions of years. Carbon is also locked away in all living things, large amounts being in trees and grasses. So when we talk about carbon emissions and global warming, we are talking about releasing carbon that has been sequestered from the atmosphere by biological processes and locked into the soil or fossil (oil, natural gas, coal) and non-fossil (wood, syngas, biomass) fuels. When forests are clear cut, or grasslands converted to monoculture cropland, or soils are depleted of organic matter, that stored carbon doesn't just disappear, it leaves with whatever was harvested and more often than not ends up in the atmosphere thus increasing the amount of solar radiation in the form of heat that gets trapped on our planet and increases rates global warming. At the same time, those carbon sequestering biological processes are stopped dead in their tracks; the system is thrown out of balance as more carbon leaves the soil than enters the soil. When the carbon is released in the form of methane, most notably from drilling for fossil fuels and modern livestock farming practices, the effect is ten times worse than carbon dioxide alone. Likewise, plants cannot grow well, or at all, in unhealthy and depleted soil. This makes it that much harder to sequester atmospheric carbon by biological processes.
The carbon cycle.
Photo credit: http://cnx.org/contents/b3c1e1d2-839c-42b0-a314-e119a8aafbdd@8.24:98/Concepts_of_Biology
Carbon rich organic matter and a healthy community of biological organisms in the soil also generally means more water in the soil. this is because decomposed and decomposing organic matter (humus) acts like a sponge, retaining up to ten times its own weight in water. Likewise, soil biota increase the water holding capacity of any soil. As well, soils rich in humus, water, and biota can support a large variety of plant life that store large amounts of water in their tissues, again most notably trees and grasses. Here's where things get really cool, more water in the soil means more water percolating deep into the ground and eventually recharging aquifers as a water savings account. As well, increased water in the soil and diverse plant life leads to greater levels of evaporation from the soil and transpiration from plants (evapotranspiration), which creates higher local humidity and rainfall. Higher humidity buffers local and regional climates against severe temperature changes and drought while increased local rainfall contributes to a healthier water cycle and supports healthier river and tributary systems, thus stabilizing local and regional climates.
With all the problems our world faces, from peak oil, to climate change, to ocean acidification, to destabilizing geopolitics, and so on, dirt just seems like another thing to add to the already out of control list. However, as we've covered, dirt is not soil and soil is innately tied to and a primary influencing factor of climate change, which is the primary influencing factor of ocean acidification, though we didn't cover the topic of oceans. Soil can also be a mitigating or exacerbating force for geopolitical relations as it relates to food production and the coming food shortages if we do not heed the warning signs that have been documented since the mid 1960s. Though GMO's are a topic for another day, it's pertinent to say that GMO's will not save us from depleted and degraded soils. The fact is no plants, not even modified ones, are going to grow in lifeless pure mineral dirt. Remember dirt is inert. Certainly carbon emissions need to be greatly reduced worldwide and resources need to be reused and recycled to a far greater extent than they are today, however soils are the most pressing and influencing problem we face. No matter what else we do to address other issues, if we can't feed ourselves, well be in really bad shape. By focusing on soil repair we will ensure our own future and the future of our children while simultaneously mitigating many of the other problems our planet and our species are facing. I look forward to sharing a more positive and upbeat look at how anyone and everyone can and should help rebuild soils worldwide. I look forward to next week for sharing soil building 101.
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