Soil, again. 3/1/2022

I was chatting over the gate with another plot-holder on my allotment this morning; he was telling me about rebuilding his compost bays, I was telling him about getting rid of mine for good a year ago. We agreed that it is good soil that grows decent crops, not a tidy plot. At least we agreed on that.

For a no dig grower, green manures are a potential problem in that they need to be gone ahead of planting the succeeding crop. That would ordinarily entail digging them in but I needed to find another way.

The Phacelia/winter tares/Italian ryegrass mix that I sowed in late August was a partial success; the Phacelia did very well, there is some rye and no sign now of winter tares, though it was evident earlier. It may have been smothered by the Phacelia, which proved very vigorous.

Today I cut down all the Phacelia in one of the two beds I’d sown with it; bagged it up, shredded it and spread it back on the same bed with some additional shredded material, cabbage stalks mainly, to get good coverage.

The Phacelia had gone leggy, with stems sprawling across the bed and much of the foliage over the paths on either side. I don’t know whether it would have been killed by frost in the next month or two, I will find out as I’ve left the other bed for now. In colder areas than Cornwall it probably would have been killed already, leaving the dead material on the surface to protect the soil and gradually get absorbed into it. I have speeded the process up. The roots are still in the ground and will die and decay in situ, releasing nutrients and adding to the soil organic matter, just in time for onions, carrots and other root crops to get maximum benefit.

It was on January 4th last year that I emptied my compost heaps across my plot and resolved to make no more. Since then I have not just been no dig, I’ve been no compost too, a shred and spread grower. I wasn’t at all sure how it would work, there didn’t seem to be anyone else doing it. There still doesn’t, but I won’t be going back to composting. Shred and spread has worked very well, generating enough mulch material to keep all the bare areas of my plot covered. It must put more nutrients back into the soil since there is no opportunity for them to be lost and the early stages of the composting process that on a heap would generate heat and produce a worm population explosion happen in the soil. I am convinced that the soil is more open and friable, even than when I was practicing no-dig with a compost mulch.

I have two plots on the allotment site. The first one I took on was deep in weeds and initially I dug it two spits deep from end to end, burying the weeds. I dug some of it in the second year, then adopted no-dig. The second plot I took on to grow Camellias. I planted them into undisturbed ground and laid fabric over the space between them to kill the weeds. They are now long gone but very little of it has been dug. I think shred and spread is a much more effective method of getting fairly infertile, somewhat compacted soil into good condition than spreading compost. Not treading on the growing areas and growing crops and cover crops are equally important.

Cover crops reduce the area of bare ground I need to mulch, plus they generate mulch material and benefit the soil directly by their presence. I need to find a wider range of suitable species since different species confer different benefits, I’d like for one or two cover crop components to be crops in their own right, perhaps perpetual spinach, broad beans, autumn sown peas or mooli radish.

Back in September I mentioned a book by Gabe Brown that gave five principles for creating and maintaining soil health. They’re worth repeating:
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.

I believe I’m well on the way to achieving the first four by my own efforts. Integrating animals was for Brown about mixing livestock with arable farming and is not scalable to a 200m2 allotment. I’m an animal and I browse the growing plants by harvesting them; I am helped by caterpillars, mice, voles, rats and the occasional rabbit. It seems to suffice.

7 thoughts on “Soil, again. 3/1/2022

  1. I would say that animals are overrated; but the native banana slugs here are supposedly very beneficial for accelerating the decay of the redwood debris. Unlike other slugs, which are so detrimental to growing vegetables, banana slugs consume only necrotic debris. They are huge slugs, who consume significant volumes of such debris. (I have never actually watched them do what they do, so can not attest to their consumption.) Redwood debris is innately resistant to decay, so the huge volumes of debris that the huge trees generate can overwhelm a garden. The trees are so tall that their debris falls over large areas, and beyond their shadows. As kids, we learned that the banana slugs keep the forest from burying itself in its own debris.

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    1. I have often read that this or that species of slug here is primarily a detrivore. Too bad the slugs don’t seem to have read any such thing. It’s been very wet and mild here lately and they’re already munching away. I’m amazed that slugs would eat redwood debris; probably shouldn’t be, in nature every niche gets filled by something.

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      1. Well, yes. It is a weird slug. Other slugs and snails are not serious problems within redwood forests. The banana slug is the only prominent slug, and it is VERY prominent. It is the mascot of the University of California at Santa Cruz.

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  2. That was an interesting read, and it is basically what I’m currently doing in the front garden. Mr S and I have been discussing the merits of no dig in the vegetable garden, which I think will benefit the vegetables enormously.

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    1. I always think my experience with no dig is very closely related to my soil, weather etc and not necessarily applicable elsewhere, but Gabe Brown’s book takes the opposite view, that the same principles apply everywhere.

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  3. I wonder if No 2 keeping the ground covered allows for a bit of weed suppressing fabric. I may be being overly optimistic there! I’ve dug my green manure in now and will cover some of the plot with the rest of my compost and for other areas I use the weed suppressor.

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    1. I don’t see Brown’s set of principles as a set of rules so much as a breakdown of the elements of a natural system that produces optimal results. Even in a natural system there will be occasions when they don’t all apply, such as in the aftermath of fire. So plant cover all year is better than for 9 months and 9 months is better than 6 months, but when growing veg the ground will be bare when the crop is first sown and immediately after it is harvested so it’s never going to be optimal.

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