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.