A couple of posts ago I mentioned the issue of tillage in the context of the permaculture movement. Here I want to discuss another issue at the core of permaculture that troubles me, namely its emphasis on perennial plants.
A key permaculture theme is to observe the natural world and then apply its lessons in conscious human design. Looking at natural plant communities globally it’s striking that almost always they’re dominated by perennial plants, with only a few annuals. Human agriculture, on the other hand, is dominated by annual plants, with only a few perennials. Supposing we could model our agriculture instead on these natural perennial plant communities – the benefits seem numerous. We wouldn’t need to till, to weed, to fertilise, to worry about soil loss or winter leaching and so on and so on. We would put less labour and less energy into our farming, and reap the benefits year after year.
So why don’t we? The literature sometimes presents the issue as a fateful choice made by our farming ancestors – a preference for domesticating annuals that, once made, was as if somebody had switched the points and committed us for ever after to the single track of a high input annual agriculture. There may be something in this. It’s possible to see why the early cultivators might have focused their efforts around annuals and then, with success, had few options but to stick with it. But this view troubles me because it fits within a narrative of modern progress and enlightenment that I frankly don’t believe – the view that our ancestors were less clever and less capable than us in spotting the possibilities for a truly sustainable and sophisticated perennial agriculture. It seems to me that if virtually all human agricultures have inverted the natural order of things by consistently favouring annuals over perennials in the long term, it’s likely due to strong underlying biological causes that are hard for agriculture to overcome, and not just cultural myopia.
J. Philip Grime’s book Plant Strategies, Vegetation Processes and Ecosystem Properties has given me a few inklings about what those causes might be. I can’t hope to convey the richness and complexity of Grime’s analysis here, but his basic point is that three fundamental plant strategies have arisen in response to three types of habitats – the ‘stress-tolerator’ strategy of a low nutrient-low disturbance habitat (think oak tree), the ‘competitor’ strategy of a high nutrient-low disturbance habitat (think nettle), and the ‘ruderal’ strategy of a high nutrient-high disturbance habitat (think chickweed). The fourth logical possibility – low nutrient-high disturbance – basically keeps plants at bay (think wind-blasted scree slope).
Most natural habitats in this schema are low nutrient-low disturbance, and even the ones that aren’t generally have a successional tendency towards it. The plants best fitted to cope with such habitats are perennial stress-tolerators with highly conservative life strategies. Nutrients are scarce, predators are legion, reproduction is risky – so stress-tolerators grow slowly, live long, reproduce cautiously (often clonally) and invest resources in making themselves unpalatable with prickles or poisons. Competitors and – more so – ruderals, on the other hand, prefer to make hay while the sun shines, investing in fast growth and prodigious reproduction at the expense of longevity and unpalatability. But they require habitat disturbance and/or high nutrient input to stave off the longer-term successional advantages of the stress-tolerators.
It’s easy to see where agriculture fits into this picture. Farming peoples want palatable and highly productive plants, and the way they’re most likely to get them is by interfering in succession and replicating ruderal/competitor situations of high disturbance and high nutrition by tilling and fertilising. The result is an agriculture based around prolific, tasty, leafy and/or seedy, mostly ruderal and mostly annual plants.
Grime’s three types are in some sense abstractions, which admit to hybrid strategies in practice. But there are still strong morphological barriers – it’s hard to be stress-tolerant and quick-growing and palatable. Human plant breeding efforts no doubt can and have pushed hard against some of these barriers, but I suspect we’ll struggle to overcome them altogether. For example fruit trees can be quite stress-tolerant, quite productive and certainly palatable – but they’re not very stress-tolerant, and their productivity has probably arisen through co-evolution with fructivorous animals as a reproductive strategy to disperse seeds a long way from the parent plant, which is no doubt why orchards are so disease-prone, and why organic orchards have been described as “the most challenging frontier an organic grower can face” (M. Phillips The Apple Grower). Likewise, most productive herbaceous perennials seem to be pretty short-lived – competitor hybrids, perhaps. Wes Jackson, probably the best known exponent of breeding for a perennial grain agriculture, reckons that it may take at least 50 years to breed a commercially viable perennial grain crop, but he points out that even if we were to develop only one it would pay dividends (Jackson, New Roots For Agriculture, pp.102-8).
I’m sure it would, and I’m sure that professional and amateur breeders should be devoting themselves more fully to the task – especially in places such as Jackson’s native Kansas where the effects of annual tillage agriculture are so manifestly destructive. But I suspect that it will be challenging. Jackson’s oft-quoted remark that “if your life’s work can be completed in your lifetime, then you’re not thinking big enough” maybe hints at his own sense of the difficulties he has embarked upon.
So where does all this lead? For me it suggests that we should support efforts to breed productive perennials – especially seed-based macronutrient-dense perennials – wherever we can, because annual tillage agriculture is pretty destructive. But it also suggests we shouldn’t bank on these efforts succeeding. It suggests that there may be a lot of good reasons for planting gardens packed with fruit and perennial vegetables, but we shouldn’t (yet) delude ourselves that these are ‘permaculture’ gardens unless we can live off them entirely without any surreptitious visits to the bakery or the chip shop (though talking of chips, a long hard look at tuberous perennials may pay dividends). For me personally, I think it means that I want to devote the majority of my farming efforts to figuring out how to grow annual crops as sustainably as I can, for example through agroecological potato growing, rather than going too far down the perennial route. Because much as I’m enjoying this perennial-intensive time of year, with all those lovely creamy spaghettis con asparagi and rhubarb crumbles, sadly it’s the spaghetti and the crumble rather than the asparagus or the rhubarb that are mostly responsible for keeping my hunger at bay. Oh, and maybe the cream as well…which of course brings us back to grass, probably the most successful perennial agriculture we’ve yet devised.
Successful it may be, but sadly an agriculture based around perennial grass isn’t successful enough to feed a planet of seven billion, at least without falling back on other aggressive ruderal strategists – such as Triticum or the notorious Glycine max. And this raises interesting questions about ‘productivity’. Since we devote a huge proportion of our croplands to livestock fodder, could we perhaps afford to push a little less hard at the productivity boundaries likely to trip up perennial grain culture if we adopted a more vegan diet? Maybe, but would it be enough? Everything points to perennial agriculture working best in low population, dispersed, intensive food gathering situations – in other words something barely resembling agriculture at all, so much as the preagricultural situation from which our early farming forebears emerged.
In Permaculture One, the founding document of the permaculture movement, Bill Mollison and David Holmgren wrote that “Permaculture, unlike modern annual crop culture, has the potential for continuous evolution towards a desirable climax state” (p.7). I think that may prove to be pretty optimistic in the face of the biological realities surrounding plant strategies. Any thoughts?