Part 3 of The Cosmos, the Earth, and Your Health – The Story of Soil
In the first two episodes of this series on how soil is formed, we’ve been operating at the cosmic level, talking about the how the elements of life were molded during the Big Bang, inside stars, and in explosive supernovae. It’s time to come back to earth, and to reverse scales from the mind-bogglingly large to the infinitesimally small.
When we left our story, the main actors had taken their places on stage; the elements critical for life had formed. Now, as we wait for the curtain to rise, we can look at the playbill to see who these characters are and why they are so beautifully suited for their roles in creating life and building soil.
We can divide the elements of life and soil into two main categories based on how they behave and what roles their structure allows them to play. (I say “in life and soil” because the two are virtually identical: Soil is where most life comes from, and there are almost no elements needed for life that can’t be found in healthy soil.) The first category is a batch that chemists call “main-group elements” because how they cluster in a large group in the periodic table. The main-group elements involved in soil include carbon, nitrogen, potassium, phosphorus, calcium, magnesium, and sulfur. These are, obviously, major players in story of soil, and copious amounts of all of them get cycled around by living things.
A second group of elements are less abundant in life, but are every bit as crucial in living processes because of their hyperactive, social-butterfly qualities. They are members of a group that chemists call “transition metals.” That word “transition” hints at the shape-shifting nature of their character that makes them so dynamic and able to play multiple roles in living things. They include iron, nickel, copper, zinc, manganese, cobalt, and molybdenum. There are many more transition metals, but those seven are the most common and the ones whose roles in life we know best.
I’ll give you some brief biographies of the major players to show what role they fill in life and likewise in soil.
First up is carbon. That’s a word that’s constantly in the news these days, and often not in a good way. But carbon has been at the center of events long before the fossil-fuel era. It’s hard to conceive of life that isn’t based on carbon. That’s because it is uniquely multi-functional among all the elements. It comes in several forms; soft graphite, hard diamond, soot, and nanotech inspiring fullerenes are each pure carbon, and each has wildly different qualities from the others. Carbon can construct nearly 10 million known compounds, vastly more than any other element. And although a few other elements can bond to one or maybe two others of its kind, only carbon can build chains of itself. When it combines with hydrogen, its most common partner, it forms a tetrahedron, and any Bucky Fuller fans out there know that tetrahedra have almost magical properties. (Water, another molecule with unexpected qualities, also forms a tetrahedron, and that’s food for thought.)
Carbon is immensely changeable, depending on what it is linked to. When hydrogen is its principal partner, it forms hydrocarbons. These are liquids such as gasoline, oils and tars, and solids such as plastic. When oxygen is added to the carbon-hydrogen pairing, the result is gums, waxes, fats, sugars, and other gooey substances that we associate with life. Adding nitrogen yields dyes, amino acids, and alkaloids such as caffeine and psilocybin. Add sulfur, and antibiotics result. Blend in phosphorus and we get DNA and a crucial energy-carrier called ATP.
It’s ability to form innumerable compounds is one reason that carbon plays such a big role in life, but there’s another reason just as powerful: It can store lots of energy when it bonds to itself, and then release that energy when those bonds break. It’s that energy that makes carbon in soil, in the form of organic matter, so important. Just as we do, soil life such as microbes and insects need a constant supply of carbon compounds for their easily available energy. When the enzymes and acids within living things break carbon bonds, the energy released is transferred to compounds in the organism such as ATP and sugar, moved to places that it is needed, and released again to power more molecule building and unbuilding. That’s most of what metabolism is: the transfer of energy from carbon compounds, otherwise known as food, from one place to another, to do various important tasks via other carbon compounds such as proteins, DNA, and vitamins that are especially suited to those tasks.
Figure 1. Some of the many forms of carbon. Even if you can’t read chemical structures, you can see that the patterns that carbon creates are many and varied.
I could write a book on the marvels of carbon (and may some day!) but before carbon’s nuggetized biography takes over this whole article, I will sum up by saying that carbon’s ability to store and move energy, and also to bond with so many other elements and thus shuttle them from place to place, make this element the backbone of life. Soil lacking in carbon—in organic matter and the soil life it breeds—is dead soil, and it creates dead food.
Nitrogen is a much-touted soil nutrient, critical but often so over-emphasized that other nutrients just as valuable get overlooked. It’s needed to build protein, which is found in structural tissues such as muscle and cell membranes, and also in enzymes, active, flexible chains of molecules that are the construction equipment of life. Enzymes weld together protein, starch, and DNA chains; push needed molecules through cell membranes; repair and regulate DNA, and do essentially all the building, transport, and disassembly that go on within living things. Every living being needs nitrogen to keep protein in good supply. Nitrogen is also a major ingredient in chlorophyll, the compound that uses sunlight to build sugar out of carbon dioxide in the air. That’s why plants green up so fast when they get a dose of nitrogen. Too much nitrogen can prompt insect damage, because bugs need lots of it and can “smell” when plants have it in overabundance.
Phosphorus stimulates root formation, improves flowering and seed production, strengthens stems and stalks, aids nitrogen-fixing bacteria, and increases disease resistance. It’s used in DNA, special fats that make up cell membranes, and in ATP, which is a principal energy-storing molecule. Phosphorus is stored in large amounts in seeds as phytin, where it can by used by the developing seedling. Phosphorus also aids in transporting other nutrients around the cell. Some scientists and activists believe we’re rapidly depleting phosphorus supplies and feel that we need to be much better at stewarding it.
Potassium’s role is less understood, but it is needed for many enzymes to function, and it helps young plants get started, in part by strengthening roots. Potassium-deficient plants are more susceptible to cold, extreme heat, drought, insect predation, and disease.
Calcium is a neglected nutrient that is just beginning to get its due. The textbooks will tell you that calcium is needed in modest amounts to build cell walls, protect against heat stress and disease, aid in nitrogen fixation by bacteria, improve fruit quality, and help in the uptake of other nutrients. That last role conceals a mountain of important and often dismissed functions for calcium. Maverick soil scientist Dr. William Albrecht was among the first to sniff out calcium’s unsung role in soil biology, nutrition and health, and his work spawned a school of advocates, including the Acres USA publishing team, and soil specialists such as Michael Astera and Steve Solomon. I recommend checking out their work for an expanded and radical view of soil minerals that has helped me immensely in growing nutrient-dense food.
For example, agricultural lime (calcium hydroxide) has been used for millennia to make acidic soils sweeter, that is, to raise their pH. But Albrecht found evidence that it’s the calcium in lime that reverses the nutrient deficiencies that common wisdom claims are due to acid pH. In other words, when soil contains enough calcium, soil acidity matters much less. This is, to put it mildly, controversial, but a view that some serious plant growers swear by. Calcium also loosens sticky clay soils. So this new school of calcium aficianados recommends much higher levels of calcium in soil than conventional agronomists. They also believe that soil levels of calcium, magnesium, potassium, sodium, iron, zinc, and a few other nutrients should be adjusted to an ideal ratio, roughly 65% calcium, 15% magnesium, 4% potassium, and 1-3% each of the others. For more on these ratios and the thinking behind them, check out http://soilminerals.com and Michael Astera’s book The Ideal Soil. For an opposing view, see what soil scientist Neal Menzies has to say.
My personal view, and the one that guides my fertilizer recipes, is that most soils benefit from adding more calcium than the conventional guides say, but there is a lot of leeway in the ratio of calcium to other nutrients. I don’t worry about achieving a perfect 65/15/3 balance, just something in the ballpark, or even in the same part of town.
Magnesium is at the center of the chlorophyll molecule, just as iron is at the heart of the very similar hemoglobin molecule in mammals. It’s essential for ferrying phosphorus and iron to where they are needed. Many of the enzymes that synthesize sugar, fats, and oils contain magnesium. In soil, it increases the stickiness of some clays, so levels that are too high can make soils gummy and even anaerobic. In soils low in clay, adding magnesium sometimes helps soil hold more water and stabilizes organic matter.
To wrap up this segment of our series on soil: Carbon builds structure and stores energy. It’s not properly a nutrient, but its presence in soil in many forms is critical for ecosystem function and everyone’s health. The elements that make up what soil folk call the primary nutrients are nitrogen, phosphorus, and potassium. Those three are, I think, overemphasized, a legacy of some of the earliest experiments done on plant nutrition that used anything resembling the scientific method. Justus von Liebig, a brilliant German chemist who made major contributions to organic chemistry and invented important chemical equipment, examined the content of ashes from grains. He found principally nitrogen, phosphorus, and potassium, and since then generations of farmers and soil scientists have concentrated on—and used staggering quantities of—these and only these as nutrients. The roles of carbon and of the other mineral nutrients were neglected for over a century, leading to depletion of most of the world’s farmable soil and a precipitous decline in nutrition in our food. The secondary nutrients, calcium and magnesium, are only secondary in sheer mass required, but not in importance to plant, soil, animal, and human health. The same goes for the trace elements. Chalk up another victory for the “quantity over quality” mindset, and a loss for all of life.
I’ve used more words than I expected to get to this point in our tale. We haven’t made it to the trace elements and why those transition metals are so magical and important—so important that some scientists joke that life arose simply as a way to move them around. We’ll talk about that next time, and begin looking at how to tailor your soil to yield lush amounts of nutrient-dense food: both quantity and quality.
Please share these articles with your friends by telling them to sign up for my newsletter at http://eepurl.com/bv-apD
DG Greeen says
What exactly is nutrient-dense food? I’ve seen a lot of info on it but I’m still not clear. How do you know that you are growing nutrient-dense food? I know that brix is associated with nutrient-dense food but I can find no research on the connection other than a lot of material that leads to Carey Reams. Is high brix=nutrient dense another dynamic accumulator type meme with little or nothing to back it up?
Toby Hemenway says
DG, excellent question. I love to see people engage in critical thinking and not just accept something as gospel. Like Nate, my personal experience with nutrient density is in noticing a huge difference in growth, taste, and appetite-satisfaction. I have some raised beds that I have intensely mineralized, and other beds that have a typical fertilized mix added to them. The growth rate, saturation of color, taste, bug and disease resistance, and feeling of satisfaction after eating for the produce from the mineralized beds is vastly more than in the control beds. As Nate says, that’s not data, it’s anecdote and subject to all sorts of bias, but it seems like a very real effect to me. And it’s the real reason that I started this series of articles.
There are labs that will analyze the mineral content of plant material. I have not sent my produce to them, but have seen reports from others who have mineralized their growing mix and found much higher levels of minerals (iron, calcium, magnesium, and so forth) in plants from those soils. Oddly enough, the best data are coming from cannabis growers: botany and chemistry nerds with a monetary interest in seeing the relationship between mineral levels and aroma, taste, and cannabinoid levels. They show a tight correlation. That information is, unfortunately, buried in a 60-page thread in a cannabis forum and I need to paw through it to find it again.
I, too, have seen posts about the supposed connection between brix and “nutrient density” but haven’t delved deep enough to see how real that correlation is. It makes sense to me that ability to produce sugars would correlate with mineral levels, since minerals are so critical for enzyme function, but then, “it makes sense to me” is not hard evidence.
I want to explore exactly this issue in the next posts in this series. Your analogy with “dynamic accumulators” is apt; I have lunch regularly with Robert Kourik, who pretty much originated that term (it’s his table you will see when you google the term) and he regrets having missed how tenuous is the actual data behind the idea. So let’s not do that again.
Thanks again for asking about this, as it’s spurred me to do some deeper digging for the rest of this series.
DG Green says
I agree with your observations about mineralized beds, having had more or less the same experience, but taste does not equal nutrition eg. a chocolate brownie that has lots of sugar tastes great and a fantastic great tasting chocolate brownie uses butter instead of oil. Taste generally means sweet. In fruits and vegetables that’s probably not a bad thing since the sugar is naturally occurring.
And there is the question of the definition of nutrient dense. Wiki is sparse on the subject – https://en.wikipedia.org/wiki/Nutrient_density . Perhaps it’s sufficient to say that the carrot that I grow in re-mineralized soil has more nutrients that the USDA standard for carrots –
Yes, there are labs that do tissue and sap testing. It seems to me that it’s time to call on the sellers of product to produce lab tests.
Perhaps a good place to start would be to design a good test. I offer the following for criticism, hopefully constructive. Part of the problem is to limit the number of variables coming into play. “Making” and isolating soil by combining a more or less mineral free peat moss with perlite for porosity in a 10 gallon pot might be a starting level playing field. Pot one would be unamended throughout the growing season. Pot two would have the standard N-P-K fertilizer applied according to the label. Pot three would have the standard N-P-K fertilizer applied according to the label and rock dust applied according to the label. Pot four would have the standard N-P-K fertilizer applied according to the label and rock dust applied according to the label and mycorrhizal fungi incorporated into the “soil” at a level say 1/2″ below where the seeds are sown so that emerging roots could be infected. All carrot seed would come from the same packet. Since all of the peat and perlite are coming from the same individual bags, there would only be the need to test one before sample. At harvest time, each of the pots would have their soil and the plant tissue tested. At the same time the plant tissue is being taken, it would also be tested for brix.
Nate, without doubt if we do something that fits our view of the world, we feel better. I don’t have a problem with that; I do it all the time. As my stress goes down, my physical and mental health goes up. However, if we are trying to design systems that are healthy for us and our environment, it seems to me that what we are doing should be well-founded. In the world of permaculture, this is particularly critical as the number of students and teachers with no experience greatly outnumbers those with experience. The better world that we are building must be robust and regenerative.
DG Green says
oddly enough, the best data are coming from cannabis growers: botany and chemistry nerds with a monetary interest in seeing the relationship between mineral levels and aroma, taste, and cannabinoid levels. They show a tight correlation. That information is, unfortunately, buried in a 60-page thread in a cannabis forum and I need to paw through it to find it again.
Yes, some of the best horticulturalists are the cannabis growers. Can you link to the thread? I’d love to work through it to see what they have to offer on the subject.
Toby Hemenway says
The thread is at https://www.icmag.com/ic/showthread.php?s=c896c13c4f7c80c7fcd99ed83e1aa526&t=312208 . The thread is called “Balancing soil minerals.” There’s a lot there, so have fun with it.
DG Green says
I wasn’t sure exactly what to search for so I chose Brix. It doesn’t come up very often an when it does it’s not very helpful except for this one post – https://www.icmag.com/ic/showpost.php?p=7123116&postcount=96
Good questions, especially the second “why aren’t we publishing mineral content of the produce, etc… to confirm that the minerals ( including trace minerals) are actually getting to the plants and not just lying in the soil in an unavailable form?”
The last worthwhile study of soil mineral content vs mineral content of crops grown, that I know of, was “Variation in Mineral Composition of Vegetables” by Bear, Toth, and Prince. The year was 1948. [this study can be found online, and is reproduced, along with comments, starting on p140 of The Ideal Soil 2014] I do not know of a single other published study comparing a broad range of soil minerals with mineral content of crops grown. is that a little strange, or what? With all of the awareness, interest, and concern about nutrition over the past 77 years since 1948, with all of the articles and studies bemoaning the loss of mineral nutrients in food and mineral depletion in the soil, not one single agronomist or nutritionist or researcher has bothered to test the soil, then test the crops grown in that soil for minerals and mineral-associated nutrients? What’s with that?
A few years back I made an attempt; I put together a volunteer group who agreed to have their soils tested and send the reports to me. I would write a soil Rx, they would amend the soil to my recommendations, grow a crop, and then have the crop analyzed for minerals. Out of fifty or sixty free soil Rx’s I wrote, perhaps eight people followed through. Rather disappointing, but the little data gathered was quite interesting. For example, Detroit Dark Red beets grown in mineral-amended soil measured, in comparison to USDA averages, an increase of
Those interested can read more at nutrientdenseproject.com
Toby Hemenway says
I’ve found a bit more on the relationship between brix and nutrient content of plants. There are a couple of posts at https://www.logicalgardener.org/viewtopic.php?f=20&t=680
and some graphs and data at https://blamingnature.wordpress.com/tag/butternut-squash/
These graphs show a pretty good correlation. I’d like to see more evidence, but it would be very convenient if measuring brix really did tell us about a plant’s nutrient content.
DC Green, I aporeciate your desire for measured results and your skeptical mind! I too am skeptical of many things. It is possible that perhaps sometimes the proof may not be a measured quantity, but a felt quality.
As one who has long struggled with his own health, When I eat organic food grown in “nutrient dense soils”, my body feels better my brain works better and I am happier and more capable of giving to others and rarely now do I feel so bad that it prevents me from pursuing my goals. I no longer have 4 doctors appointments a month, I have a daily appointment in my garden.
I know my anecdote is a far cry from a peer reviewed research paper, however it is a truthful account of my life experience. Try it and see!
Comfry and Chamomile,
Josh Simon says
I believe the relation to a high brix reading and high nutrient density would closely correlate with the microbiological activity in the soil. This could work in partnership with plants to produce the nutrients that a plant needs. I believe after what I have heard from Elaine Ingham and Gabe Brown that that high nutrient density is only really possible in the presence of a healthy biologically active soil ( no till ) that is either balanced between fungal and bacterial biomes or enhanced when fungal networks are in greater abundance than the bacterial elements of the soil but not too much (acidity). Gabe Brown has a good graph of this near the end of a recent keynote speech given just over a month ago. Here it is: https://youtu.be/ExXwGkJ1oGI