I have complex thoughts on why I don’t teach or really promote Elaine Ingham‘s soil food web approach much. I get asked about this a lot.
First, a lot of people are passionate about this, so if using a microscope to make friends with your soil critters has improved your experience of gardening, have at it! There is room for anything that makes us feel more connected to our land. For some, seeing their invisible soil allies is essentially a spiritual experience!
I appreciate her work in promoting current science on WHY soil biology has a huge impact on optimal plant growth, and helping people conceptually understand the soil food web so they stop doing standard horticulture and agriculture practices that disrupt it. It’s good for us to know these basics. I teach them in my PDC.
But to my knowledge, there is no research yet demonstrating the value of her “3 step approach,” or at least the first two steps, identify missing microbes and introduce them. Avoiding spraying g and tilling is a research based approach to my reeding.
Over the years she has sold or endorsed various products to introduce microbes, so that part has changed over the years.
That’s probably because we DO have tons of science showing that “brute force methods” of trying to introduce microbes, such as microbial teas, “hummus“ (which we now know is just regular compost with less total nutrient) or other specialty compost products, don’t work as well as just creating good microbial habitat.
So things that are research-based approaches for creating diverse healthy microbiomes, with tons of research, are: deep, diverse mulches, no dig, regulating soil moisture, no spraying of biocides, Polyculture interplantings, contiguous healthy ecosystems like forests, hedgerows and especially wetlands. In the tropics, biochar is an intensive method that deserves special mention. Just adding regular compost (even just slow composted manure) is less effective than these methods. But proven more effective than adding designer microbial inoculations. Much of this research has been posted in the research based permaculture group.
The attached document includes a bunch of methods that are proven to increase soil carbon and microbial diversity, and even maintain or increase nitrogen without adding it. enough Polyculture is now proven in a few studies to increase soil N even without n fixers. 4 plus inches of organic mulches may provide all the N we need, and improve biodiversity and carbon, whether we know what microbes are or not.
So, my main critique is based as usual on my laziness and the Pareto curve, 80/20 principle. A forest or wetland will have a diverse, healthy microflora without taking the time to ever microscope it.
And we really still can’t beat the yields that French Intensive gardeners were getting 100 years ago, using a system that involved deep mulching with composted stable bedding, minimal tilling, dense Polyculture interplantings, and minimal spraying into diverse healthy ecosystems. They didn’t understand the soil food web, but they were using research based approaches that we know now create a healthy soil food web.
When it comes to sustainable closed loop yields, many indigenous systems using techniques above are still unmatched today in terms of NET yield at low time costs and all a microscope would do is add another time and information intensive task with little potential return. Asian farmers using humanure integrated animals and flood fertigation did as good a job as we do of accomplishing sustainable yields with no microscopes.
I do think soil succession research is useful and I could infer that there is research that demonstrates its value, but there is no direct research yet that has proven it cost effective. And again, we don’t need a microscope to match plants to their ecosystems, just plant forest plants in forest conditions and prairie plants on prairie.
But I am grateful to the scientists for showing us WHY that works!
There is still a lot to be figured out in applying soil biodiversity knowledge to regenerative agriculture on a broad scale, and to my liking, no one has quite figured out replicable systems that work with modern equipment, maintain ecosystem health, sequester net carbon, don’t run on exploited labor and produce similar yields to conventional Ag. So maybe that research is on the way and will change my mind.
Until then, I don’t believe using a microscope or paying for special soil food web tests will increase the already high yields at super low time and input costs that I get from using the research based methods I mention above, and I haven’t seen research to make me think my students will really benefit from that time consuming work, either.