Composting.

When something in gardening is agreed by absolutely everyone to be a good thing it seems perverse to ask the question “why?”. I tend to the view that that is when it most needs to be asked.

Composting and the multiple benefits of compost are among of the great untouchable sacred cows of gardening, especially among the organic fraternity. However, ask a bunch of gardeners to explain why and I bet you’d get a very mixed bag of responses. Ken Thompson, author of a book on compost, called “Compost”, says “Few things are better for your plants and for the environment than home made compost”.  He then goes on to explain how decaying plant material ends up as humus. He points out though that only a small proportion of the original material ends up as humus, the rest being broken down to carbon dioxide and water.

The breakdown process is effected  by microbes which secrete mucilages that bind soil particles together into crumbs, creating what is known as “soil structure”. However, a protein called glomalin, produced by mycorrhizal fungi, has been found to be present in soils in far greater amounts than humus, and it is largely glomalin that aggregates soil into crumbs, not humus. Since the mycorrhizal fungus is getting its nutrition from its symbiotic partner, the growing plant, not from organic matter added to the soil, the humus derived from compost is somewhat sidelined in the narrative. It is growing plants (including weeds) and their associated mycorrhiza, that are doing the heavy lifting when it comes to soil improvement.

Wikipedia has a bullet point list of the benefits of soil organic matter and humus, the first of which is that organic matter feeds microorganisms, maintaining high and healthy levels of soil life. There is an implication in much of what you read that there is a direct correlation between lots of life in a soil and how well plants will grow in it. To which I would ask why, in commercial horticulture, do nurserymen almost all grow nursery stock in the all but sterile medium of peat and tomato growers in equally sterile variations of hydroponics.

Plants have evolved to grow in an extraordinary range of environments. The ferns growing on my neighbour’s roof, or the sedum around my other neighbour’s chimney, do not have their roots in a lovely friable living soil. Yet they survive perfectly well. Plants that need constant moisture or higher levels of nutrients would struggle or even die, but could all be grown in a peat nursery compost or by hydroponics.

The role played by the living and once living fraction of soil then is to provide the simple things that plants require, water, air and simple inorganic nutrients. A soil in good condition is open enough to allow the free passage of excess water whilst retaining good quantities in the porous organic matter. It holds nutrients sufficiently tightly for them not to be leached by rain, but loosely enough to be readily available to plants.

Humus, organic matter derived from but no longer recognisable as decomposing plant material, is beneficial to the soil in many ways. It adds to a soil’s cation exchange capacity and its water holding capacity. It acts as a buffer against excessively acidic or alkaline conditions and can absorb toxic materials such as heavy metals and excess nutrients.

Another claim about composting that is not true is that all the nutrients in the plant material added to the heap are retained within the heap. One study found that nearly a quarter of the nitrogen in mixed organic refuse was lost in the first twenty weeks of composting, probably mainly as gaseous ammonia. Adding soil to the mix stopped the loss, presumably because the ammonia was absorbed by the clay fraction of the soil. Additionally, any liquid draining from the heap will be taking dissolved potassium with it.

Composting can generate high temperatures, but only if there is sufficient volume of material for heat loss to be reduced enough. The small volume of a typical domestic compost heap has far too high a surface area to volume ratio to heat sufficiently to destroy weed seeds and plant pathogens.

It turns out that simply mixing plant wastes into the soil, or spreading it on the surface and letting worms do the mixing, adds more humus and more nutrients to the soil than if it is composted first and  has also been shown to produce higher yields. The relatively coarse nature of uncomposted material means that adding it to light sandy soils might make them even more open to the detriment of the crop, whereas compost holds much more moisture and will reduce the openness of the soil. On heavy soils there will be a benefit from the opening up of the soil.

What I have been unable to find any reference to is the benefits arising from the early stages of breakdown of organic matter if that takes place in the soil rather than on the compost heap. It seems to me that the level of activity in the early stages is far greater than in the later stages. The very rapid build up of heat, the product of respiration by bacteria, within hours of a pile of suitable material being stacked up, followed by a peak in worm activity in the weeks following, is then followed by a tailing off of activity and a finished product which is not generating any heat or supporting hardly any fauna visible to the naked eye.

It is worth pointing out that nature does not build compost heaps. Plants die down in autumn, or leaves fall from trees, and breakdown happens at ambient temperature. A significant amount of vegetation may be eaten by herbivores and the breakdown process is then well under way when it is deposited on the soil surface.

So it seems to be the case that we put stuff onto a compost heap for convenience. During the growing season there may be no bare ground on which to spread organic material. It is sometimes suggested that fresh material encourages slugs, but if they eat it, rather than the crop, they become part of the solution and less of a problem.

Almost all of what goes on my allotment compost heaps goes through my shredder first, so it breaks down to a material I can use for mulching in my no-dig regime quite quickly. Most of what I accumulate over the growing season is used for mulching bare ground ahead of the winter. There isn’t too much opportunity for nutrients to be lost to the heap in that time, rainfall would likely never be sufficient to run through the heap removing soluble nutrients. Soft material such as peas and beans gets mixed with woodier material like hedge trimmings.

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Pea haulms, shredded and spread directly on the soil.

I believe it is very beneficial to have any bare ground covered in the winter to protect its structure and I have used compost for that purpose. What I am now planning to do is to spread shredded material directly onto the plot where bare ground appears that I am not planning to crop again until spring. I would anticipate the softer material disappearing quickly, the tougher stuff remaining to provide protection to the soil. If a suitable area presents itself, I shall do half with composted material, the other half with uncomposted material. Then if I grow the same crop in both areas I can look for any visible differences.

References.
Roger Brook – The no dig gardener – http://www.nodiggardener.co.uk/search/label/Glomalin
USDA AgResearch Magazine – https://agresearchmag.ars.usda.gov/2002/sep/soil
E. W. Russell – Soil Conditions and Plant Growth 10th edition. Composting – pp 271-3

 

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On not digging.

In a few days time I shall be 65. Digging is either good exercise or hard work, depending on your perspective. Mine is that it is hard work and getting harder, so it seems to me that if I can get results as good without digging as with, why would I dig.

Like many people, my no-dig guru of choice is Charles Dowding, who has been promoting no-dig vegetable growing for many years and has spoken, written and blogged about his techniques at great length. I have read some of his stuff, he is not overly prescriptive about his techniques, saying that people must tailor them to their own circumstances. This I have done in the much shorter length of time I have used the no-dig approach. That length of time is in fact less than two seasons and I am very aware that it is early days and I have much to learn.

I tend to think of no-dig as a method, not a philosophy. I am doing it because it is giving me the results I want with an input that I can manage and hopefully will be able to manage for many more years to come. Part of that longer view is that my soil is being kept in good shape, but I primarily see that as a means to an end; sustained production; not an end in itself. If soil health were the end, I would have a wild flower meadow or woodland, neither of which are permitted under allotment rules.

So much for the backdrop. At a practical level, my method is very simple. I have a standard sized allotment which I have divided up into beds about 4 feet wide, separated by paths about 18 inches wide. The beds are marked only by canes at the ends of the paths, there is no structure, no timber edging, no raised beds, no path surfacing. I walk on and work from the paths and avoid stepping onto the beds as far as I possibly can, especially when the soil is wet.

In the autumn I spread a layer of compost over all the unoccupied beds, aiming for 1-2 inches depth of material. In the spring I either sow or plant into the beds, usually in rows along the length of the beds. I have had very much better results with growing seedlings in modules or pots and planting them out than with direct sowing. The only things sown directly in 2017 were parsnips and peas. I even did one variety of peas in pots and will likely do more next year.

I tried last year to follow my early crops; peas and potatoes, with later ones; spinach, chard and brassicas. It wasn’t a great success in that the late crops didn’t make enough growth by the winter to be usable or to stand well against winter weather. I’m trying a few different things this year but expect to have more empty ground than last year.  Where there are growing crops I cannot apply a compost mulch in autumn, so I have been putting it on as soon as the ground is cleared in spring. Sometimes there is a period of a few weeks before I want to plant an area, sometimes not. Rather than planting through the compost layer I have used a fork to work it into the top few inches of the bed, pretty much in lieu of worm activity.

Where I have had brassicas growing, the ground seems to become far more compacted than elsewhere. In my four year crop rotation I have potatoes following brassicas and under traditional cultivation the ground would be heavily manured for them. Other than pulling up the previous crop I haven’t disturbed the ground but have planted the potatoes and then covered the bed with 3-4 inches of compost. I don’t think this has worked well; the potatoes have not grown as well as I would have liked. Next spring I will disturb the ground with a fork but not turn it over, then mulch, working some of it into the top few inches.
I have read that brassicas don’t support the mycorrhizal fungi  that most other veg do, so digging after brassicas will not be destroying them.

I generate as much compost as I can, taking material from the allotment, my garden, the kitchen and anywhere else I can. Practically all of it goes through a shredder before going on the heap. I have three heaps and when one is finished I turn the newest one into the space and start again. The new material always goes into the middle bay and is then turned over into an outer bay when one is emptied. I am not much bothered how long it has been composting, it makes no difference to its effectiveness as a protective layer on the soil and younger material probably retains more of its nutrient content. Sometimes there can be a preponderance of dead leaves or shredded woody material and I suspect that there is some nitrogen lockup in the areas where this ends up, but I try to mix it up when I turn the heap so it hasn’t been a major issue.

I have on occasion spread soft shreddings and grass clippings directly onto the ground. The impression I have is that it provokes something of a feeding frenzy in the soil fauna, particularly the bigger members like worms, and gets incorporated, consumed and broken down very quickly. I would do more but a) I am afraid of encouraging slugs, b) it is material that is mostly available in the growing season when there isn’t much bare ground to spread it on, and c) if I spread it green, it will not be available as compost in the autumn.

In most areas of my plot I would say that the soil structure is excellent. It is easy to plant things and just as easy to pull them, and the weeds, out. Cornwall is a relatively high rainfall area so I think the amount of nutrient loss from leaching is bound to be a bit higher than in lower rainfall areas.
As effective as organic matter may be at retaining nutrients, some will always be in the soil water and available to plant roots. That fraction of the soil’s nutrients must be vulnerable to leaching and will be replaced from the reserve of nutrients that is loosely combined with organic and clay particles in the soil. The rapid passage of water down through my well structured soil will increase the leaching losses, at least when the soil is at field capacity, which it should be in a normal winter.
The consequence of this is that as much as I would like not to have to add nutrients over and above those contained in my compost, I do have to if I am to get maximum yields from heavy feeding crops.

One additional factor is moles. Both my plot and compost heaps are plagued by them. On the assumption that most of the hard work that I am saving myself from is being done by worms, I see moles as serious predators of my workforce. I shall try growing caper spurge next year, to supplement my largely unsuccessful trapping.

So, in summary, no-dig is a method where you put organic matter onto the surface and the “cultivation” is done by the soil fauna working it into the soil profile. The compost should provide all the nutrients required by the crop. Broadly I find it works well, but occasionally I find a small amount of cultivation by myself is required. I also believe that some additional fertilizer is needed to get the best yields.
To some extent I think I am still undoing the damage done by previous years of conventional cultivation but I am pleased with my results so far. There are some indications that while my results are being sustained or improving, others on the site are doing less well.

Time will tell.

Allotment half term report.

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Midsummer seems like an appropriate time to take stock. Most things have done well; I think I have the soil management side of things where I want it. My failures and problems are not soil related: cabbage root fly, not enough water and as of today, mice going for my peas.

The one thing that I haven’t quite resolved with the no-dig regime relates to the areas where brassicas stand all winter. Bare ground I have mulched with compost in autumn, ground planted with leeks and parsnips in late winter. By spring when I want to start planting the ground is in good condition.

The brassicas stay until March or April and I’ve been following them almost immediately with potatoes. The soil seems to be more compacted after the brassica rotation than any other and there is no time for a mulch to get taken down into the soil before the spuds need to go in. I think I will loosen it with a fork next year, without turning it over, then work some compost into the top inch or two of soil. My Charlotte earlies have done well but the second early Kestrels are not looking brilliant.

Garlic has been terrible for the second year running. Higher fertility, more water and quite a lot of lime may provide the solution.

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Pea ‘Twinkle’, about 40 cm tall.

 

I grew Meteor peas this year and have had a couple of pickings. The flavour has been compared unfavourably to Greenshaft, which I will go back to next year. Twinkle is a very short variety not requiring support. They’re very nearly ready, look to have a good crop and taste sweet eaten raw.

Enviromesh was a good purchase for protecting my carrots, which are carrot fly free for the first time. I think the mesh also traps heat and slows wind; the foliage is particularly lush under it. I’ve simply laid it over wire hoops and buried the edges. I will try some salad items like mizuna and radishes under it next year, hoping it will stop flea beetle.

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Runner beans and broad beans.

The runner beans have started flowering, the inevitable glut is not far off. I will not worry so much about leaving beans unpicked this year, they were very usable as dried beans last year. Broad beans can and will be frozen, they are more appropriate to our winter menus than summer salads. Bamboo “rails” are providing support on my windy plot.

Allotment update – 9/5/2017

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Onion Brunswick

 

I decided to give onions from seed another go this year. I have grown the red onion ‘Brunswick’ and a Spanish variety called Liria, from real Seeds. Brunswick I pricked off singly into modules, the twenty to a half-tray size. Liria I did singly, in pairs and in threes. Yesterday I planted them all on my plot.

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Onion Liria by threes, twos and ones.

I’d also made an early sowing of leeks which I’d pricked out into a 2 litre deep pot. They were about a foot tall so I planted them too. I was surprised to get 35 from the pot.

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Musselburgh leeks

Elsewhere on the plot I’ve recently planted out lettuce, trying to grow pretty by edging a path with alternate green and red.

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Lettuce sitting pretty, broad beans behind, pot grown peas Onward in front.

My early sowing of Meteor peas need support; I’m hoping that the later Twinkle, which was described as short and self supporting, will need little or none.
I had some Onward peas from last year and not confident that they would still grow, sowed them in pots. They’re all planted out now. Sugar Peas I have direct sown.

My direct sown parsnips seem to have started coming up and disappearing again. That has been my experience with almost all direct sown stuff. Whether ’tis slugs or leatherjackets or wireworms or some’at else I don’t know.
Some of the mulch material I spread in the autumn had a lot of shredded leaves in it. Possibly partly because it was a dry winter, they are largely still there. I think slugs are hiding beneath them and attacking cabbages I planted through them. I’m now working any compost I apply just before planting into the soil surface a bit to avoid that happening.

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Spuds, outer rows Kestrel, inner rows Charlotte.

Spuds aren’t looking bad, just hope the blight stays away long enough to get a decent crop.

Gooseberry sawfly is rampant this year. They are the undisputed champions of hiding in plain sight. You squash every one; the following day there are hundreds more.

Allotment update 14/4/2017

I’ve put in several hours on my plot yesterday and today, strimming, weeding, sowing and planting. It still feels early in the season but I’m well on the way to a full house.

I’ve said before that I have trouble getting seedlings going on my plot and start most things off in pots or cells. Today I planted out some carrots done in deep pots – I think they had seedling trees in them in an earlier life – and sowed another batch as soon as I got home. I sowed parsnips next to the carrots and covered the lot with fine mesh to keep out carrot fly. I hope that works, they did a lot of damage to last years crops.

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Carrot Early Nantes

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Carrot fly protection for carrots and parsnips.

I grew Flower Sprouts for the first time last year. They did very well so I have them again. I am trying two different cabbages this year, Huzarro and Delight Ball. The Flower Sprouts replaced overwintered and fairly useless Chard. I’ll give the spinach alongside a few more weeks. All thes brassicas had been sown in seed compost and pricked off into Sylvagrow peat free. They’ve done well but the cabbages are a bit soft.

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Brassicas in 5cm cells.

My first sowing of perpetual spinach was in cells in Jack’s Magic compost, a peat based product that I have now used up and won’t be using again. That’s less because it’s peat than because it hasn’t given me good results. The spinach was sown under cover on 1st March and is looking hungry. It has been planted where the leeks were and since I am

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Hungry spinach, planted out with last years leeks.

still digging and eating them, I haven’t mulched the ground. The no-dig model of mulching bare ground in autumn works well but it’s not so easy to fit in an annual mulch when there is an overwinter crop being followed by direct sown seeds or small transplants. Perhaps I shall top dress with compost when the plants get bigger.

Today I sowed in pots beetroot, cabbage, carrots, cauliflower, courgettes, butternut squash, purple sprouting broccoli, purple curly kale, sweetcorn, parsley, peas, spinach, sorrel and giant goosefoot. I have no idea how I am going to fit it all in.

Allotment update – 3/4/2017

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My purple curly kale has had it. Time to go. I chopped round the stems with the spade, leaving most of the roots in the ground and took them away to be shredded and added to the compost heap.
I’d wanted to plant spuds in the space nearly a month ago but thought there were still a few more pickings, so those potatoes went into 1L pots in the tunnel. Today they got planted out and unsurprisingly are well ahead of the others. This is Kestrel, which I saved from last year. I planted a row on 5 March and some are up, others not. None of the Charlotte’s planted at the same time are up. Perhaps I should have started them in pots too.

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I had a bit of old carpet which I cut into strips and laid on some of my “paths” to save weeding. I fear they will provide slugs with hiding places, equally it may work to roll it back every few days and kill them.
The purple sprouting broccoli at the left was sown 25 May and planted out 12 August. Too late, it didn’t really make the growth before winter.

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The mesh I laid over early peas has worked and they’re now coming up. I took off the mesh before the peas became entangled in it. Broad beans which I planted 17 March are looking pretty good.

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Pea ‘Meteor’, sown 13 March.

 

I had struggled with onion sets until another plot holder suggested starting them in cells. Last year I had my best onions ever. I planted them in cells on 12 March and planted them out today. I gave them a couple of weeks longer in cells last year but the roots seemed quite well developed and the forecast isn’t bad, so I went ahead. I’ve kept one tray back for later, see what the difference is.

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Onion ‘Rumba’ sets in 20 cell half trays.

 

Elsewhere on the plot I still have lots of leaks and parsnips which are not going to get eaten. I shall put them through the shredder and compost them. I don’t see it as waste, more as production of raw material for compost, of which there can never be too much.

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And finally, in the fruit cage blueberries and gooseberries are flowering like mad. I have several different blueberries, the best of which is ‘Darrow’, with huge tasty fruits. I took a few cuttings of it last summer and it looks like some of them have rooted. Be a year or two before they start to crop though.

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Blueberry ‘Bluecrop’

 

The star turn fruit wise last year was the blackcurrants that I left steeping in vodka until after Christmas. Strained it off, added some sugar and I have something very drinkable indeed. More this year I think.

Allotment note 13/3/2017

There’s very much a sense of the season accelerating; that transition from not enough to too much to do. This was my week, as far as veg goes.

5/3/17 Planted potatoes Charlotte and Kestrel. I planted Kestrel 18/3 lst year and they were fine so I should be OK. I’ve put more Kestrel in pots to go out when Purple Curly Kale gives up. There’s 3 inches of compost where they are planted, which I shall use for earthing up, maybe with more added if needed.

My fruit bushes are breaking bud, I gave them a lightish feed with Vitax Q4HN.

Today I sowed Pea Meteor on the plot. Not grown it before. My one attempt at autumn sowing failed, in Cornwall too many slugs are active all winter I think. I’ve put mesh over the top to deter mice, though I haven’t had problems in the past.

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Peas protected, hopefully, from mice.

 

Also sowed, in pots, Lettuce Red Salad Bowl, Black Seeded Simpson and Lollo Rosso as well as Cucumber Carmen. I’ve planted my Rumba Onion sets in cell trays to get them started.

To the right of the peas in the picture is an area where I spread some finely shredded leaves in the autumn. They have done an excellent job of protecting the soil beneath but haven’t broken down at all. If repeated it needs to be a very thin topping, they are a bit in the way of planting and sowing. I’m slightly surprised it didn’t blow away.