Soil, getting it good and keeping it that way.

I’ve had my allotment since April 2013 and have been a committed no-digger since about two years in. I could see what was happening to my soil, the good structure (aggregation into granules) that it had when I started very quickly started to break down.

I stopped digging and divided the plot into beds about 1m wide with narrow paths between them. I worked from the paths, trying never to stand on the beds and started trying to produce enough compost to keep the soil surface covered all the time that it didn’t have a growing crop in it.

At the beginning of this year I dug out all my compost and spread it over the ground. I hadn’t spread it in autumn as I usually did, so except for weeds, the ground was largely bare. I decided I would stop keeping a compost heap and instead just shred everything and spread it wherever there was space.

Seven months on that still seems like a sensible decision. A month ago I stumbled upon a writer called Ruth Stout who was doing something similar back in the 1960’s. Since then I have come across the concept of regenerative agriculture and its various cheerleaders. I read a book called Dirt to Soil by Gabe Brown, which tells of his journey from failing conventional farming to successful no-till farming in North Dakota. It was the fact that so much of what he was saying was obviously relevant to my situation in spite of the massive difference in our circumstances that gave it such impact.

Having bought Brown’s book on Amazon I have of course been bombarded with suggestions of books in similar vein. There are a lot, as far as I can judge covering pretty much the same ground.

Much of what is written about growing sustainably has an aura of pseudoscience or mysticism hanging around it which I find very off-putting. Brown steers well clear, describing what he did to restore his soil and the science he drew on along the way. Farming being at heart a business, he is much concerned with his bottom line; he believes in what he is doing but it still has to bring in more money than goes out.

At the outset, Brown sets out his stall in straightforward fashion. Our lives depend on soil. The importance of maintaining its ability to support food production globally cannot be overstated, yet the way it is cultivated in much of the world is destroying it. There are, he says, five principles to creating and maintaining soil health.
1 Limit mechanical, chemical and physical disturbance of soil.
2 Keep soil covered at all times, as far as possible with growing plants.
3 Strive for diversity.
4 Maintain living root systems in the soil at all times.
5 Integrate animals.

Reading the book left me thinking I’d made a start but had quite a way to go. He goes on to explain each of these principals and how to achieve them in practice, albeit in an agricultural situation. It all made perfect sense to me though it was obvious that I would need to interpret his principles to take account of my different circumstances.

I am now thinking that the no-dig practice of simply covering the ground with compost in winter is not so much wrong as that it doesn’t go far enough. I’m harvesting crops like peas and potatoes mid summer, then, because I’ve not had much success with follow on crops, have kept the ground unplanted until the following spring. Brown maintains that it is root exudates from living roots that are the main building blocks of carbon in the soil and that organic matter on the soil surface, while conferring physical benefits, mainly breaks down, releasing carbon dioxide.

Somewhat inevitably, reading the book in August, I had left it a little late to try much out this season. It was too late for follow on crops so I have done a bit of experimenting with cover crops. Sow Seeds sell a wide range of green manure crops and initially I purchased Phacelia and crimson clover from them. A couple of chapters further on in the book and I went back to them with a further order, for winter tares, red clover and Italian rye.

A part row of Phacelia, from a sowing in July, most of which was slugged. At right angles to it you can just see rows of rye, Phacelia, winter tares and red clover emerging, sown more recently. I’ve left a few caper spurge and one Malva sylvestris to see how they fit in. The groundsel needs to be removed.

Brown makes the point that different plants contribute different things to the soil ecosystem, some fix nitrogen, some root deep, bringing up nutrients, and so on. I went for a certain amount of diversity. I had two beds in which I had grown potatoes and on which I had spread a layer of shredded material which was mainly still there as a dried out layer. In one I sowed a mix of seeds in drills around 200mm apart; in the other I broadcast the seed then worked it into the surface with the tines of a fork. Germination is much better on the drilled bed, presumably because the seeds are deeper where there is more moisture. The layer of shreddings on the surface doesn’t seem to have impeded growth at all.

I have also been considering what else I could include in a cover crop mix. It seems to me that leafy biennials like foxgloves and Verbascum might be good. They could be sown mid summer and would make a lot of leaf to protect the soil surface in winter while their roots supported the soil micro-organisms. They would be easy to cut at ground level in spring ahead of planting crops. I could mix them with conventional green manure species for more diversity. I could also try mixing them with crop species, maybe interplant peas, broad beans or spinach beet, any yield from which would be better than nothing.

Nothing grows in a North Dakota winter but I don’t live there, I live in Cornwall, where things slow down but they don’t stop. In theory at least, it should be relatively easy for me. Perhaps ideally I would find crops that would occupy the ground from mid summer to spring so that I could harvest something while the soil was being protected and nourished. If a crop was 75% cover and 25% usable I wouldn’t be complaining. Brown gets extra value from his cover crops by feeding it to his livestock. In my scenario, the integrated animals are going to be me, voles and slugs.

Thinking about Foxgloves and Verbascum, both of which grow as weeds already on my plot, I had a long hard look at the rest of my weed population, wondering whether there were others that would be as good at green manure/cover crop as they are at being weeds.

Some seemed to have potential:
Euphorbia lathyrus (originally planted to deter moles – it failed at that but grew well enough.)
Malva sylvestris (a garden escape)
Dandelions (are you mad! Deep rooted perennial, potentially bringing nutrients up from way below, could be sliced of at ground level regularly to prevent seeding or competing with crops)

Out and out weeds that would no doubt grow amongst any cover crop and need to be removed, mostly prolific seeders, some prolific spreaders.
Groundsel (Senecio vulgaris)
Hairy Bittercress (Cardamine hirsuta)
Willowherbs (Epilobium spp.)
Spurge (Euphorbia peplus)
Chickweed (Stellaria media)
Sow thistle (Sonchus spp.)
Spreading yellow sorrel – purple leaved form (Oxalis corniculata)
Pearlwort (Sagina procumbens)
Annual meadow grass (Poa annua)
Heartsease (Viola tricolor)
Nettles (Urtica spp.)

If there are any of you further down the road on these things than I am I’d love to hear about your experiences. I should probably dive back into the murky waters of permaculture, see if I can find someone prepared to be honest about how little they really know about soil. I believe I know enough to distinguish the empiricists from the pseudoscientists, the proselytizers from the open minds. I have hauled myself out of those waters before, feeling exhausted and frustrated at the time I’ve wasted.

The science that gave us an agricultural system based on artificial fertiliser, chemicals and big machines has little choice but to accept that it got it wrong. There appears to be a new generation of scientists who acknoeledge that the soil ecosystem is highly complex and inherently difficult to investigate without at least altering, if not destroying, the very thing they are investigating. It is also highly subject to wider environmental factors such as weather, climate and geology, so varies greatly between locations and seasons. Careful observations of real-world scenarios are becoming recognized as much more useful than laboratory work. It is more important to know what really works in the real world than to know precisely how it works; that can come later.

References.
Gabe Brown. Dirt to Soil: One Family’s Journey into Regenerative Agriculture. You can read a sizeable sample on Amazon.
Brown’s book has a list of further reading, both books and websites, which I have only just started to check out. Here are a couple of them.
Amazing Carbon, a series of papers by Dr Christine Jones.
Bionutrient Food Association



11 thoughts on “Soil, getting it good and keeping it that way.

  1. Interesting. Have you noticed soil structure improvement since you stopped digging? I’m about to tackle my weed-filled “vegetable garden”. It was a disaster this year – partly because it was too hot for me to work it, plus the drought. I was thinking of clearing it, then putting down cardboard and wood chips for the winter, but now am wondering if a cover crop would be better. I’m in Minnesota, so won’t have anything actually growing from about November through March.

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    1. There is no question that my soil is much improved since I stopped digging, though I hesitate to put it all down to that. I have protected the soil surface in winter with compost or green manures and avoided stepping on, which I’m sure have helped too. Given that Gabe Brown is farming in North Dakota, his experience would be very relevant to your area I would think. Linda Chalker-Scott (Garden Professors) wades into the cardboard mulch argument here: https://gardenprofessors.com/the-cardboard-controversy/#comment-17511 My own instincts would be against a wood chip mulch for a vegetable growing area because it would take too long to break down. Anything generally used for weed suppression is going to make vegetable growing much more difficult. You presumably get too cold a winter for a cover crop to survive the winter and in any case, it’s pretty late to get anything going now.

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  2. Great post. I generally try to get some green manure in after the potatoes (although haven’t got that far this year) – last year Phacelia, previous years I’ve tried Ryegrass and Crimson clover. The main problem I’ve had with them is poor germination. As you mention, broadcast sowing does leave the seeds vulnerable to drying out.

    The thing that happens most often on my allotment after things are harvested is that the ground gets intensely weedy, so it does conform, accidentally, to some of the principles you mention. I like your idea of allowing/choosing some of the weeds to grow, just focusing on the real nuisances. I always let Fumaria officinalis grow because of it’s association with Corydalis, not because of any real benefit.

    Anyway, thanks for posting – plenty to think about!

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    1. Given how elusive a solid definition of “weed” is, I did my best to focus on what would be an asset and what a liability. Weeds score highly on what for me is priority number one, slugs generally leave them alone. I’ll probably trial a whole range of potential cover crops next year, though it must already have been done, I should probably trawl the internet first.

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    1. It’s an intriguing thought that grazing animals, constantly on the move because of predators, so only grazing and trampling lightly before moving on, would get a growth response from the plants such that you get more carbon capture rather than less. The trouble with slugs is they stay put and destroy one plant before moving on to the next. I need to hire a goat for half an hour perhaps.

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  3. I would be interested to know what you use to shred your material before spreading it. I used to have a chipper but gave that away when I downsided to a smaller garden. That did not take the softer material well, and I always had to encourage it through with tougher sticks etc. I wonder whether there is a smaller shredder which you would recommend I don’t have a mower as I have no grass. Thanks Jim

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    1. I had a couple of Bosch AXT 2200 machines but both went wrong not many months after the warranty expired. They were not good on soft stuff so I was forever unblocking them. I now have a Stihl GHE 250 and to be honest it also doesn’t like soft stuff and needs unblocking just as much. There’s a tacit admission of as much in that the Stihl GHE 355, externally similar looking, has a complicated sounding blade reversing function for doing soft material. Costs a LOT more though. A google search throws up Pyracantha.co.uk recommending the Bosch AXT 25 TC as coping exceptionally well with all types of material and it scores highly on Amazon rankings. Lot of money for a small garden shredder though.

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      1. Thanks Jim, I think for the small amount of stuff and garden, and lack of storage space, I shall just cover as best I can. In anycase not much gets left bare..think of the garden not the gardener! I keep well covered up whatever the season.

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  4. An interesting post, Jim.

    Re shredders: I use a Stihl GHE 355 and find it quite good. The problem material comes from those plants with strap-like leaves – watsonias, crocosmias, iris, hemerocallis etc. These are quite fibrous and, unless the blades are kept well sharpened, shredding them is a struggle with regular blockages. I generally simply put these directly onto the compost bin and, as I have good quantities of composting material, they do break down.

    I have raised beds in the vegetable patch and have added our own garden compost over the years, initially in quite large amounts and less nowadays as the soil level is up to the top of the timber of the bed frame. I have found the soil has become very loose and open over the years, having started from a fairly heavy loam and it is now distinctly different to the soil in the general garden, being very light and easy to work. I never walk on it and haven’t made any special efforts to keep it covered over the winter – there will be overwintering onions, garlic, spinach, broadbeans, and sprouting broccoli, of course and these are rotated around the beds.

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