Thinking like an Ecosystem

Last week’s post on composting had, as my more perceptive readers will probably have noted, more than one agenda. First on the list, obviously, was the straightforward goal of getting as many people as possible to start practicing one of the simplest and most useful skills in the green wizard repertoire, and getting plant nutrients out of the waste stream and into the soil in the process. Still, there’s more involved here than that sensible step.

Composting, as I mentioned in passing last week, is more than just a core technology for organic gardening. It’s also a template on which a much broader range of approaches to sustainability can be modeled – or, rather, need to be modeled. It’s crucial to keep this in mind, because quite a few people who are discussing sustainability these days, with the best intentions in the world, are doing so from within the presuppositions of our current, utterly unsustainable civilization, and getting thoroughly bollixed up by the resulting misperceptions.

Organic gardening tends to be particularly prone to this sort of confusion, because the way most people grow food crops in the industrial world today – sensible and reasonable as it seems to us – is perhaps the best example of sheer, rank, bullheaded ecological stupidity on record in the last couple of thousand years or so. To grow food crops in today’s world, do you draw on the dozens of readily available and sustainable sources of plant nutrients, which happen to be the sources that plants have evolved to assimilate most readily? Do you cooperate with the soil’s ecology, which has coevolved with plants to store, distribute, and dispense these same nutrients to plants? Do you even recognize that food plants, like every other living thing, are part of ecological communities, and thrive best when those communities receive the very modest resources they need to flourish?

Not a chance. No, you get your nutrients from nonrenewable sources, because that’s where you can get them in chemically pure and highly concentrated forms, even though plants don’t benefit from having them in those forms; you treat soil as though it was a sterile medium serving only to hold plants upright and provide a sponge to hold irrigation water and chemicals, and then do your best to make it a sterile medium; you use chemical poisons to stomp the crap out of any attempt by any other living thing to help form an ecosystem involving your plants; and then you wonder why you’re stuck in a perpetual uphill battle against declining soil fertility, chemical-resistant weeds and bugs, water supplies poisoned with chemical runoff, and all the rest of it. If some evil genius had set out to invent an agricultural system that was guaranteed to self-destruct as messily as possible, I’m not sure he could have done a better job.

Still, because these are the customs we’ve all grown up with, the ways of thinking fostered by this sort of giddy ecological idiocy seem like common sense to most people. Recent discussions about “peak phosphorus” are a case in point. Our current agriculture relies on mineral phosphates, which are mined from a small number of highly concentrated phosphate rock deposits that located in odd corners of the world and are being depleted at a rapid pace. (Does this sound familiar?) The conclusion too often drawn from this is that the world faces mass starvation in the near future, because you can’t grow food crops without phosphate for fertilizer, and where will we get the phosphate?

There’s a point to these worries, since our current agricultural system is probably incapable of churning out food at anything like its current pace without those rapidly depleting mineral inputs, and even the very rapid expansion of organic farming under way in North America and elsewhere probably won’t be fast enough to prevent shortfalls. Still, it has too often been generalized into a claim that the exhaustion of rock phosphate reserves means inevitable mass famine, and this is true only to the extent that current notions of industrial agriculture remain welded into place and nobody gets to work building the next agriculture in the interstices of the present system.

It may already have occurred to my readers, after all, and has certainly occurred to me, that somehow plants grew all over the world’s land surfaces in vast abundance for something like three quarters of a billion years without any phosphate fertilizer at all. If this suggests that there’s something wrong with the logic that insists that we can’t grow plants without chemicals, it should. Nor are food crops somehow uniquely dependent on stuff out of test tubes. As proof of this, I’d like to invite you to visit a city that doesn’t exist any more, the bustling metropolis of Edo.

It’s called Tokyo nowadays, and there’s very little left of the city that was there a century and a half ago, but in the Tokugawa era – from 1603 to 1867 – Edo, then Japan’s real though unofficial capitol, had a population that varied between one and one and a half million people. Two other cities – Kyoto, the official capitol, and Osaka, the economic hub of the nation – had populations pushing a million each. Even by modern standards, then, these were cities of considerable size, and they were supported by organic intensive rice agriculture that used no chemical inputs at all. The inputs it used were human and animal manure, nitrogen extracted from the air by a common and deliberately cultivated species of duckweed, and a great deal of human labor, and its outputs kept levels of nutrition in Tokugawa Japan at levels comparable to those of European nations of the same time.

Without phosphate rock, why didn’t the Tokugawa-era Japanese all starve to death? Because ours is very nearly the only agricultural system in human history that has ever approached farming with the same sort of logic that governs a factory: energy and raw materials in one end, products and waste out the other, with no thought as to the long-term availability of the first two or the long-term effects of the last. Everywhere else in the world, farmers have known for time out of mind that life moves in circles, and that you have to feed the soil if you want the soil to feed you, and that proper husbandry pays off in richer soil and better yields even when you don’t have access to outside nutrient streams.

Thus in natural ecosystems, in 17th-century Japan, and in any other viable ecology, human or otherwise, the phosphorus used to grow plants doesn’t move in a straight line from phosphate mine to factory to farm to river to dead zone in the Gulf of Mexico. It moves in a circle, from producer to consumer to decomposer and back again. That’s true when the producer is grass, the consumer is a rabbit, and the decomposers are soil organisms that process the rabbit’s droppings; it’s equally true when the producer is a rice paddy, the consumer is a medieval Japanese farmer or samurai, and the decomposers are a different set of microorganisms. Finally, it’s just as true when the producers are your garden plants, the consumer is you, and the decomposers are in your compost pile.

In each case, the result is the same: a relatively small addition of nutrients from outside sources goes a much longer way in a system that works according to ecological processes, because the ecosystem recycles the nutrients back into the plants instead of letting them go into the waste stream. The more efficiently you keep things circling, the less you need to add from outside the system. If you can learn to think like an ecosystem, this will become as obvious as the need for vast amounts of concentrated mineral inputs seems to so many people today.

At the same time, out there in the real world, there are always inputs from outside the system, just as there are always flows out of the system into other systems, and you can learn to take advantage of those inputs. All through your topsoil and down a short distance into the subsoil, for example, humic acids – complex natural compounds produced by decaying organic matter – silently dissolve nutrients in rock particles and make them available to soil organisms and plants. The nutrient inputs that come via this route are usually fairly small, but they add up over time, and their effectiveness depends on a thriving soil ecosystem and enough organic matter in the soil to produce the humic acids.

The duckweed in rice paddies mentioned a few paragraphs back is an example of an even more crucial source of inputs. Nitrogen is a nutrient that doesn’t normally occur in soils in anything like useful quantities; fortunately there’s this big reservoir of it, right next to your soil, called the atmosphere. Various microbes spread out along the shifting taxonomic borderline between fungi and bacteria can process nitrogen from the air into nitrates and other forms that plants can use, and quite a few plants have evolved the trick of feeding and fostering those microbes so that the soil where they grow ends up full of useful nitrogen. Putting that process to work for you is one of the fastest ways to make an organic garden thrive. Unless you’re setting up rice paddies and shopping for duckweed, the plants you want to use for nitrogen fixation are legumes: peas, beans, and their relatives, which not coincidentally are a major source of protein and other nutrients your body needs.

Now of course most of us have yet another source of inputs, and it’s the one we talked about setting up last week. Even if you’ve got a thriving organic garden in your back yard, you’re almost certainly getting at least some of your food from other sources, and if you’re in the very first stages of setting up that soon-to-be-thriving organic garden, you’re getting all your food from other sources. The scraps and trimmings that go into your compost bin are therefore nutrient inputs to your garden. If you’re raking up autumn leaves and adding them in, or mowing your lawn, letting the trimmings dry out a bit, and putting them into your compost, that’s another input. This is the secret function of your compost bin: it’s a tool for concentrating nutrients from a wider area into the piece of ground you garden.

More broadly, that’s one of the secrets of successful organic gardening: you close up your nutrient cycles as tightly as possible, but you also tap into other nutrient streams that would otherwise become waste, and draw them into the eager clutches of your garden’s ecology. Traditional farming methods around the world turned this sort of thing into a fine art, weaving farms and gardens into the wider ecology of the area in richly complex ways. All this needs to be done in ways that don’t impair the viability of the systems that provide inputs to your garden, but that can be done easily enough in most cases, given a bit of finesse and a sensitivity to ecological relationships.

Your options here are very broad, and will depend on local conditions. Still, here are three common approaches to add to what you can get via the compost bin.

The first method is mulching. In many parts of North America, this has become a staple technique of organic gardeners, and for good reason; in other places, for equally good reasons, nobody does it. You get large quantities of coarse and otherwise unwanted organic material – for example, spoiled hay, autumn leaves, straw, or crushed peanut hulls – and spread a layer several inches thick over your garden beds before planting; when you plant, clear away the mulch around the seedling or the seed so it can get sunlight. The layer of mulch helps suppress weeds, keeps moisture in the soil, and gradually rots, adding nutrients to your soil.

Drawbacks? When I lived in the rainy part of the Pacific Northwest, nobody in their right mind mulched during the growing season, because mulch in damp climates is a slug magnet, and slugs in the wet zone west of the Cascades can get up to eight inches long, with appetites to match. I’ve heard from a few gardeners who had similar troubles with rats. Of course you also have to find a source of clean organic matter in bulk, and this can be a challenge in some situations.

The second method is green manure. This amounts to a living mulch for the winter season: something fast-growing that you can sow in your garden beds when the weather starts to cool off, and hoe under in the spring just before planting. The best green manures for small garden use in many cases are clovers, which are legumes and put nitrogen in your soil, and rye grass, which produces a lot of organic matter relatively quickly and breaks down easily in the soil to feed the organisms there. If you mulch, you won’t be able to use green manure, and vice versa; both are good approaches, and it’s probably worth your while to try them both on different patches of ground to see what works best in your area.

The third method is the tried and true trick of growing an abundance of legumes in your garden. Done right, anywhere in the temperate zone, this is a three-step process: you plant peas as early in spring as you can work the soil; you plant beans as soon as the weather is warm enough for them, and then you plant a second round of peas for fall harvest about the time the summer peaks and begins to decline into autumn. Any kind of pea or bean will do, so choose whatever kinds you like to eat, and plant as many as space permits; if you grow the kind that are eaten green, you can always blanch and freeze anything you can’t eat in season, and if you grow the kind that are dried and shelled, an extra pound or two of dried beans or peas in the root cellar is always a good thing to have.

There are many other ways to work the same transfer of nutrients. It’s important not to become too dependent on any source of outside nutrients that could be shut off unexpectedly – say, by problems with the economy – and it’s even more important to make sure that the inputs that you use are the sort of thing that will support the ecology of your garden rather than damaging it, as chemical fertilizers will. Within those limits, there are plenty of options; see what you can come up with.


The three methods discussed in this post vary widely in ease of information access. You can find plenty of information about growing peas and beans in any decent book on organic gardening, while green manuring is not that common in the organic field just now, for some reason, and I don’t know of a good book that covers it in any detail; my knowledge is partly a matter of experience and partly brief discussions in some of those same decent books on organic gardening, in particular John Seymour’s The Self-Sufficient Gardener. (If any of my readers know of a book specifically about this technique, suitable for home gardeners, I’d welcome the information.)

Mulching is another matter, not least because the organic gardening world has been through at least one round of pre-internet flame wars between pro-mulching and anti-mulching factions. The classic books here are by Ruth Stout, How to Have a Green Thumb without an Aching Back, and Ruth Stout and Richard Clemence, The Ruth Stout No-Work Garden Book. Those interested in all the fine details might also look for Robert Rodale et al., The Organic Way to Mulching.


A tip of the wizard's hat to reader Liz Brugman, who took the time to convert all of the Master Conserver handouts into individual searchable PDF files. The first five are available on the Cultural Conservers website, and the rest will be following shortly. Liz has asked that any corrections be sent to her at gb.heron (at) gmail (dot) com.