Here’s something I’ve been meaning to write about since February, when I heard Elaine Ingham talking about soil food webs at the Canadian organic growers conference. Dr Ingham is one of the main movers and shakers behind this apparently increasingly influential perspective, which has found its way into the gardening firmament through books like Lowenfels and Lewis’s Teaming With Microbes. The idea in a nutshell is that plant/crop growth is interdependent with a complex web of small, mostly soil-living organisms. Plants exude proteins and carbohydrates into the soil, funded from their photosynthetic way of life, which provides food most importantly for bacteria and fungi, and thence to a vast array of other single- and multi-celled critters whose life and death in the soil provides the complex nutritive foundation upon which the larger organisms intelligible in the everyday human world build their lives – the trees, the shrubs, the grasses, the forbs, the birds, the mammals, the reptiles, the molluscs, the arthropods and so on.
Two main points emerge from this of relevance for farmers. The first is that despite our impressive level of human knowledge about the chemistry of soils and plants, we don’t really know exactly what our crop plants need to thrive at any given time – only the plants know that (‘know’, that is, in a biochemical sense – which brings to mind this nice article by Richard Mabey about plants as authors of their destinies in ways not always suspected by humans). So instead of fiddling about with idealised fertiliser regimens, we’d be better off just providing the plants with healthy soils teeming with life, and let the plants themselves get on with the job of self-nutrition. This is basically the familiar adage of the organic movement: feed the soil, not the plant. A further, unproven, implication is that plants which have been able to optimise their self-nutrition may better enable us, their predators, to optimise our own.
The second point concerns precisely how you ‘feed the soil’. What you don’t do, according to Dr Ingham, is add synthetic fertilisers or pesticides, because these salty additives kill soil life. Nor do you till, because this does the same – particularly in the case of delicate fungal hyphae, which are torn apart by ploughs and harrows. So instead you add compost – lots of it. That’s how you feed the soil.
Not just feed the soil, in fact, but according to Dr Ingham actually build it. She was scornful of the USDA agronomists who claim that soils form at a rate of (I think she said) one millimetre per year. She informed us that she could make a soil thirty feet deep in two days (or some such improbable amount…I forget the exact figure…), evidenced by her work to create a native Texan prairie in just one year at the gardens of the George W. Bush Presidential Library in Dallas, where her photos showed us trucks dropping off compost by the ton1. Cue astonished wows and whoops from the audience…
…and an uncontrollably arching eyebrow from me. It’s not, of course, that I question the morality of working to beautify the legacy of the USA’s 43rd president. Because, let’s face it, no amount of native Texan flora could make Mr Bush come up smelling rosy. No, it’s because…because…well, JUST WHERE THE HELL IS ALL THAT COMPOST COMING FROM? Surely from the detritus of an American agricultural civilization which, though it accumulates in centres of human population, ultimately stems directly or indirectly from its farmland. Let’s put it another way: if you put your mind and a decent number of large trucks to it, you can probably produce and spread compost several feet thick over the 13 acres of the George W. Bush Presidential Library and several other such institutions besides. What, I’d submit, you can’t do is spread it over the 900 million plus acres of farmland in the USA where I suspect the overall rate of soil formation is more likely going to approximate to that disparaged USDA figure, and then only if you’re lucky.
The implications of all this are potentially significant. First, I suppose I should pose the question as to whether Dr Ingham’s arguments are sound. There are those who would doubtless argue that farmers have been merrily tilling and spraying their fields for a long time now and nobody’s died yet – well, nobody identifiable anyway, apart perhaps from a few farmers. Personally I find it plausible that we’ll have to look after both soils and soil food webs better than we presently do if agriculture is to continue to serve humanity well long-term. And there does seem to be some evidence that repeated fertiliser and pesticide applications aren’t good for soils, but I’d be interested to hear more expert views than mine on this.
On a garden scale, I think it’d be quite easy to grow food in no-till beds nurtured by compost made on site. True, that’s partly because in a domestic growing situation people are rarely producing all their own food so there’s a net nutrient inflow – particularly in modern industrial societies awash with cheap energy and fertiliser. In a self-provisioning or ‘peasant’ situation it’d be harder, but probably still doable with careful attention to human and animal wastes, compost crops and the like. This is something I plan to start trialling soon and will hopefully be able to write about in the future with my own data to hand.
In a broadscale farming situation, though, it’s tricky to see a solution. You could go for the conventional no till approach with synthetic fertilisers and pesticides. You could go for the organic approach with clover leys and tillage. But both fall foul of Dr Ingham’s strictures. I suppose you may be able to establish some kind of permanent pasture and/or biomass crop with a cut & compost or graze & confine regimen, which enabled you to transfer nutrients to the crop. But I imagine it would be quite inefficient in terms of per hectare yields and possibly also energy inputs. Maybe organic no till methods will prove feasible, with crops established in a clover sward.
In southern England where I live, the cool, moist climate and heavy soils make for a very forgiving environment for tillage farming. The annual crops that we grow prosper in bacterially rather than fungally dominant soils, and bacteria are relatively little affected by tillage. So the system I’ve adopted has essentially been a standard organic ley and tillage one, albeit with a few closed-ish loop, no till affectations thrown in. But there are lots of good reasons to try to avoid tillage, especially if Ingham is right and you need a decent level of fungal hyphae in the soil even for annual agricultural crops to prosper. So maybe my present approach will prove unsustainable in the long run. But the George W. Bush presidential library approach is certainly unsustainable in the long run. Fitting, perhaps, for a rather unsustainable president. So are we then left only with the peasant self-provisioning option? Nurture your own soil, grow your own vegetables, compost your own excrement…oh and buy land, they’re not making it anymore, as Mark Twain had it. Or at least only at 1mm per year.
Well, that’s a familiar bottom line conclusion for me to reach. This website ain’t called ‘small farm future’ for nothing. Even so, my feeling is that Ingham’s no till, soil food web approach may be something of an ideal, and there’s room for messier compromises to be made with the world. It may be best not to till for soil, plant and human health, but perhaps the world is not so black and white that a judicious bit of tillage here and there is so impermissible. But perhaps that’s wrong. Perhaps, somewhere, or perhaps even everywhere, a long biological soil clock is starting to tick down on human agriculture.
- In September 2016 I received an email from Laura Solano of Michael Van Valkenburgh Associates Inc, stating that Dr Ingham did not work on the George W. Bush Presidential Center project. See http://www.mvvainc.com/