Harnessing the power of fungi to restore soil fertility

You know you read those descriptions of plant soil requirements – ‘Any reasonably fertile, well-drained soil’, like no fool would garden in soil that wasn’t reasonably fertile and well drained? Well some of us fools do. I battle with low fertility, alkaline pH and patchy drainage. I recently had a full soil analysis done, and the pH is 8.1 and the soil is deficient in organic matter and most minerals, although the zinc level is freakishly high for some reason that will need investigating.

Drainage is a funny one here because we are in Blackmore Vale, legendary for its boggy clay, but the level of my plot has been raised by about a metre against the flooding, mostly with rubble, and it is surrounded by a major ditch (or moat, depending on the weather), so it is very sharply drained close to the ditch and progressively boggier with every metre you move away from it.

In the annual veg garden I built raised beds and filled them with composted cow manure from Komit Kompost, which needed to be topped up annually for the first few years as the compost broke down. This is the traditional approach – bring in tonnes of soil improver. It worked well and now it is a great growing medium for veg, but I can’t afford the cost or the back power to apply this to the whole of a one-acre plot,  so I need to do something different elsewhere. Plus, everywhere else I want to grow perennial plants, and as soon as the roots go down into the subsoil, they will encounter the original hostile conditions. While I grow lovely shallow-rooted veg, the trees that I have planted mostly look stunted and unhappy.

Digital image
The veg garden

I have a theory. I read about a compost tower, where you bury a 6 inch soil pipe vertically, with several feet of it in the soil and a foot or so sticking out, with a bung in the end. You chop up your compost materials small and add them, and they break down and feed the soil. The beauty of it is that it only takes up a 6-inch diameter space, and you can apply it where you need it, no shovelling required. The downside is the need to chop up the materials small and the need to bury it 3 feet down – I would need a minidigger to do that and would excavate several boulders! Plus, it’s a solution for a small garden, not the scale I work on.

So I have made a different kind of compost tower, three of them, from four pallets screwed together, for the forest garden. So far, so standard. In conventional composting, you would take out the contents, turn them, replace them, do this three times, then shovel the compost out and take it where you want it. Way too much work! The capacity for hard labour does not increase with age, and let’s just say I’m looking for easier ways to do things these days!

dsc_06651I continually add compost materials to the top of this tower, but I never turn it or interfere with it. For a lid I regularly add a layer of cardboard held down with planks. And that’s it. I have never dug this piece of land. It is about 150 feet by 50 feet, and I used mycorrhizal fungi when I planted the apple trees. By now, the native mycorrhizals plus the added ones should be thriving. Mycorrhizal fungi are incredible organisms, as are all fungi.  Connected to the plants’ roots, they are the soil’s internet. In un-dug soil, if a plant is attacked by a pest, another of the same species tens of metres away will produce deterrents to that pest – it is the mycorrhizal fungi that enable this kind of communication. They also distribute soil nutrients from areas where there are plenty to areas that are deficient. When you dig, you break up the mycelium and destroy the mycorrhizal network. It’s one of the biggest arguments for no-dig.

With three strategically placed sources of compost on the plot, with the soil undisturbed, I figure that the mycorrhizals over time will distribute the nutrients from the compost and improve the whole plot. In addition, I am including plenty of nitrogen fixing and mineral accumulating plants in my planting plan, and hopefully the fertility of the plot will improve from lousy to at least reasonable over a few years. Repeat testing will tell.

As the compost in the towers shrinks down, I just top it up with whatever I can lay my hands on. My one  rule is ‘nothing thorny’. In time it will stop shrinking, at which time I will unscrew the sides, level the heap and start again elsewhere. The towers are not things of beauty I will confess, but I am a fair way off worrying about beauty on this particular plot. It’s all about getting an ecosystem going that’s not all hogweed, docks and nettles.

Will it work? We shall see. As with all proper gardening projects, it will take a few years to come to fruition, not a single weekend with Alan Titchmarsh supervising.



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I grow veg on my one-acre garden in Blackmore Vale, Dorset, and I cook, preserve and write about it. I am developing a perennial veg 'edimental' garden, and a forest garden, as well as a conventional veg patch. Earlier blogs can be found at wendypillar.co.uk

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