Monday, February 20, 2012

Soil : Ashes to ashes, dust to dust.

 "Remember that you are dust, and to dust you shall return". With these words, Episcopalians will receive ash crosses on their foreheads this Wednesday, to mark the beginning of Lent, forty days of penitence and fasting.
     It is a particularly favorite worship service for me, in that it recognizes centrally the transitory nature of physical life, yet does so without condemnation or demeaning of that same physical existence. I mention it here as an introduction to talking about that dust from which we all spring, and to which we all return, the soil itself. Soil remains a fundamental aspect of sustainable living, yet it is poorly understood, overlooked, and too often treated "like dirt", a simile whose existence tells you about our cultural values.

     Healthy soil isn't dirt. Dirt is an inorganic mishmash of mineral particles. Soil is dirt suffused with organic materials, living things, water, and nutrients. If soil is a lake in the woods, fish leaping from the water and cranes tip-toeing through the lilypads, then dirt is a swimming pool filled with sterile tapwater. We've barely scratched the surface of the ecosystems present in healthy soil, but we've determined a few key points:
(1) Dirt provides nothing more than anchoring for plants; it has to be fed and fertilized constantly for plant growth to occur, as it has negligible "nutritional value". The difference between soil and dirt is the difference between eating vitamin-fortified oatmeal, and eating boiled cardboard.
(2) Dirt is, in effect, immuno-suppressed. Lacking normal soil life, dirt presents no resistance or competition to colonizing pathogens. Therefore, growing in dirt requires constant use of pesticides, fungicides, and insecticides.
(3) Dirt cannot hold water or dissolved nutrients well. Soil holds water and dissolved ions (potassium, nitrates, calcium, etc) exceedingly well, both in the living organisms themselves, and in chemical "traps" like humic acids. Dirt generally holds either no water at all (sandier soils) or forms a nearly-impermeable barrier (clays with no organic matter), neither of which help.

So clearly, we all know to farm on soil, not dirt? Except that isn't what we do. Our current food system depends on artificially-fertilized and propped-up dirt. We actually degrade the soil year after year by planting the same few high-value crops, pillaging the complex nutrient web then trying to "replace" it with massive doses of simple, single-chemical fertilizers. Again, from a human perspective, it's like eating all of the fresh, just-picked apples and pears out of your bowl, then "replacing" them for the next meal with a bowl full of powdered sugar and tap water (since, hey, they are roughly similar chemically speaking, right?) 

Historical perspective on soil destruction comes chillingly. Remember the dust bowl of the 30s, with parts of the great plains turning to dead, dusty, crop-killing emptiness? Less than a century previous, the first farmers in the great plains planted in top soil that was six feet deep. Millenia of migrating bison, pooping and grazing and turning up the soil, then migrating away for years before returning, had build an unfathomable store of soil wealth, which we tore through and washed out to sea in three generations. The magnificent cedar forests of Lebanon are mentioned in the Hebrew bible, in the Epic of Gilgamesh, and in ancient accounts of Lebanon as a country of deep green forests, verdant pastures, and rich life. Currently, much of Lebanon is dry scrubland, which happens when you cut down all of the trees. The loss of trees means little holds the soil together. The loss of soil means little can grow back to replenish the soil. And so forth.
     What can we do? Lots, actually, remembering that there are regions on Earth where humans have farmed for four thousand years, by maintaining soil health. This is a hugely complex subject, but some key points stand out:

1) Buy sustainably grown food. Get to know your food producers, and don't be afraid to ask questions about how they do what they do. Be an educated consumer - it's your planet, too, and this is stuff you are putting in your body.

2) COMPOST. Start a pile, or contribute to a friend's pile. Every time you remove matter from an area - you harvest fruit, haul away grass clippings, etc - all the stored energy and nutrients leaves the local system. Either the local system just gets weaker and weaker (the dust bowl) or you have to replenish that lost material (compost being the good, soil-building way; massive fertilizer use being the short-term, semi-effective way.) Once you start composting, you'll also be amazed at how much less total trash your household produces.

3) Make choices that build the soil, rather than mining it. Perennial (growing year after year, as opposed to annuals, which grow for one year and die) crops, trees, berry brambles - these send deep, soil-cultivating roots, and sequester more carbon every passing year, and help solidify and strengthen the local microclimate. Look into perennial vegetables like asparagus, taro, Good King Henry, sorrel, artichoke, Jerusalem artichoke, and perennial varieties of kale. If some of these are unfamiliar, don't feel bad - our food system shifted to almost exclusively annual crops in the last century, due in part to the mechanization of farming.

4) Bare soil is dirt in the making. Plant cover crops to hold and build the soil. Make your lawn much lower maintenance by switching to a clover lawn, or a mix of grasses and clovers. This also creates soil-building life, as clover is a nitrogen fixer.

5) Hugelkultur. Aren't you tired of me talking about this yet? If not, start reading here.

6) Biochar. More on this later.

7) Learn that many "annuals" are only annuals because we force them to be. An article on perennial garlic, featuring a man who understands how to stack functions like a master.

An excellent TED talk which covers many of these points.


  1. Excellent article: really interesting and well-written. :)

    Thanks for the list of perennial veggies. Hopefully I can find some of these. The sunchokes, perennial kale, and asparagus sound especially appealing.

    I'd love for you to do a post with more detail about composting. Our lovely landlady gave us a composter. I read up on what I could, but I think I need a "for dummies" version. It's pretty full now (about 75% full) so we've stopped throwing our veggie scraps into it. It kind of kills me to be throwing the veggie scraps in the trash, blegh. For the most part the compost has been a refrigerator for veggie scraps. How do we get the composting to start, and when should I expect it to start generating heat? I did what I could find were the right things to do: added layers of soil (including lots of earth worms!), added layers of dry leaves, as well as the layers of veggies. I rotated it about once a week. It started to look good until the weather got cold, so maybe it's just a fact of life for it to go dormant in the winter? Another question I have about composting: how long does a "batch" take: one year, two years? Or does it depend, and you'll know it's ready when it's ready?

    Again, I'm really loving the blog. Keep 'em coming!

  2. Hello MGS! :-)

    I will do a more detailed post on compost, probably once the weather warms a little bit. Which segues to a few answers: the biochemistry driving compost is really temperature dependent. With a larger, well-established pile, or a pile made with experienced practice, the organic material insulates the whole thing pretty well and the bacterial action warms it from within. Often, however, most piles' decomposition simply slows down a lot once the temperature gets cold, and piles often freeze solid in the winter. Again, you can avoid this partially with practice and experience.

    A big factor that may be slowing down your pile is particle size. Since composting is just biochemistry writ large, surface area plays an enormous role. What takes months to decompose as-is will break down in a week if you are willing to put the effort and energy into shredding it into confetti. Since I'm very Taoist (or as they say in the literature, "lazy") regarding composting, I usually don't bother except with big, cellulose-heavy stalks and the like, but I accept that this means much slower "cooking" for the pile. Bigger particle size also makes the compost much less insulated, as air and water can convect heat away more freely.

    How does the pile smell? If it smells rotten (sulfurous, swampy), that generally means too little oxygen. If it smells acrid or ammoniac, that's too much free nitrogen. If it smells dusty, that's usually too dry and/or low nitrogen.

    What is the moisture level? Ideal compost feels like a squeezed-out sponge; plenty of water available for microorganisms but not saturated. If it's dry, nothing will happen at all; if it's wet, you'll get anaerobic breakdown (which will totally work, it's just slow and stinky.)

    What kind of wildlife are you getting in the pile? Flies and maggots mean a pile that is too cold and anaerobic. Earthworms mean that the moisture level is okay, but the pile isn't getting very hot, although the earthworms can do most of the heavy lifting themselves so that's okay.

    1. Rotation is good, but can also actually hamper the growth of bacteria if you keep rotating the center of the pile, where heat starts to develop, out to the edges where the thermophilic bacteria die off. It also sort of "resets" the whole pile to the stage of whatever is newest. For a small-scale operation, I might recommend just letting it stack up, so that you can get good material from the bottom even while the top has fresh scraps on it.
      This is also really dependent on what kind of material bulks up your pile - something like grass clippings, which tend to form water- and air-impermeable mats, need much more fluffing and turning than piles of kitchen scraps.

      Frequently, piles need more nitrogen. Urine can be added straight to the pile, no dilution necessary, as a free and easy nitrates source. Fresh green material helps, but is hard to get this time of year. The rapid-cooking, three-weeks-to-done piles you see experts make are almost always layers of fresh-mown grass and/or bird droppings (super nitrogen sources) mixed with food waste and heavy carbon stuff (straw, wood chips, dry leaves.)

      Time to finish a pile is very much like time to finish a chemical reaction - you can usually set an upper and lower bound, but beyond that, it's entirely dependent on conditions. A pile with sufficient moisture, some nitrogen (which it can get from food scraps), and some carbon, just left to its own devices, can cook for years and still have recognizable chunks of food waste in it. The same pile, shredded to little bits and intermixed with higher-nitrogen stuff (decomposing bacteria can run 50% protein by weight, so they are superheavy nitrogen feeders) may turn into crumbly, moist, black loam in a month.

      At this point, limited space and opportunities constrain my compost alchemy, so I usually let stuff cook until I'm digging beds, however soon that is, then just trench compost.
      When I'm running a larger-scale operation, I plan to get deeper into deliberate careful compost chemistry.

      Washington State's page on composting has good information:

      Hope this helps!

    2. Wow, this is super helpful. Thanks!