Oh yes you can. You don't have to dig your vegetable garden
Read last friday’s post about clay as homework and now read on.
|This spade has woodworm. It won’t dig clay anymore|
I am frequently told by gardeners that my ideas are quite interesting but they have heavy clay. It's a gooey mess when wet and rock hard when dry and surplus water just won't drain away. They just have to dig to do anything with it.
People just don't accept that their hard work digging which gives immediate short term gratification will in the long run destroy soil structure so that by the end of the season - or sooner - they must dig it again. Just junkies getting their fix. The very process of exposing delicate crumbs to wind and water separates out the fine clay particles to display them in tooth and claw. Ready to toast hard or puddle together when wet.
Soil structure is not just much loved crumbs in a handful of soil, it belongs to the whole soil profile. A good soil is honeycombed with channels, cracks and connections through which air and water can move. Worms wriggle and spread organic fertility. Worm-casts accumulate on the surface to enable a fine tilth. A firm settled surface gives the gardener access in all kinds of weather without causing compaction. Most of the gardening world confuses a firm settled surface with compaction!
One of the problems with clay is that the broken up cultivated clay soil goes between transitions from acceptable loosened soil to horrible stickiness and hard rockiness over a very short period of time. By the end of the season just as the soil is starting to get closer to nature the wretched digger digs it again and returns to square one.
He is correct to believe that his roughed up soil when exposed to winter freezing and drying will develop a nice frost mould in Spring. He is wrong to assume that an un-dug soil will not benefit in the same way.
The real benefits of not digging take a few years to come through. After the first season results start to show, but the real pay off takes several years. It is worth waiting a few years just to experience the pleasure of kicking out a lovely seedbed - although as you modify your growing techniques you will probably be doing more planting than sowing as you pop your plants into nicks from your spade.
Oh the joy of no weeds! You of course eliminated the perennial weed at the very beginning. Weeds from seed eventually decline as a result of your new sense of purpose and extra available time and you now never let weeds seed. The hundred years-worth of buried weed seed is no more brought to the surface each year by cultivation.
Let your plants do the work to improve your soil when you grow your vegetables and flowers all the year round. No longer should allotments be abandoned for the winter. You will merely stroll round to kill the very few weeds, crop lovely winter vegetables and view beautiful spring flowers.
I am a great believer in deep and wide-spreading winter brassica roots to improve the structure of clay soil. Early reader Grant Penner wrote in about clay-busting daikon radish to break up clay without any digging. He told all his friends but they never believed him. Brassica roots have recently had a very bad press: they do not make mycorrhizal associations. They might not accumulate wonderful glomalin but they are still fantastic soil improvers.
|Note that permanent roots grow in the cracks in the clay. Cracks in clay soils open and close in the same place with wetting and drying. Don’t disrupt air and water movement, root growth and worm action by digging!|
What about no dig for growing vegetables?
I am more strident than usual to make my point today. I hope my earlier posts have given a more balanced view of the merits of cultivations. I am in truth quite ambivalent about what other vegetable growers do and fully recognise that many 'normal' gardeners grow better vegetables than I do.
What I do care about are those diggers who shred the roots of their plants when they dig borders in the rest of the garden.
What I learnt at Oxford. (On the local allotments, silly)
Why so few vegetable gardeners fail to use minimum cultivation.
|Any volunteers to take on this allotment? Ironically the soil will be in better condition than when it was regularly dug|
I have walked around several allotments recently. I am convinced that many gardeners just do not 'get' weeds. If you cannot control your weeds you need soil cultivation. When sixty years ago farmers started to use herbicides it was widely believed that soil needed to be stirred! Much research was carried out which showed that without regular cultivation yields of many plants, especially perennials, were higher than ever. It was concluded the only real need for cultivating soil was to control weeds.
|Clay soil dug in May is bad practice. This gardener has buried his ‘frost mould’. Look at the fleshy rhizomes of bindweed. What superb propagation!|
|Dave has a nice frost mould that can be knocked into a seedbed|
When I saw on these allotments so many gardeners failing to have a rational weed control policy the horrible truth suddenly hit me. They are slaves to their weeds and have to chop them away or at the end of the season bury them to have a clean start.
Hardly a clean start with buried roots of couch, ground elder, convolvulus and much more!
|Get the sprayer out Dave - this couch is quite receptive to glyphosate. Get rid of it for ever!|
When I recently went down to brother-in-law's allotment he had several weedy areas well way from his vegetables. They were just right to spray. Dave has eliminated most of his own perennial weed with glyphosate but there was some couch grass very receptive to weed killing spray. You don't have to spray with Roundup to eliminate perennial weeds but it certainly helps. (I concede that there are many brilliant organic gardeners - who would not be seen dead with a sprayer - who don’t dig).
|I am working on Dave to recycle his weeds.|
|Dave kindly dug down to his subsoil - and a worm popped out of its tunnel to say hello|
The importance of bulky organic matter
Bulky organic matter is the secret ingredient to improve clay soil. Why dig weeds out and take this manna away when weed can be sprayed with glyphosate and desiccate and die in situ.
Not only does digging out weeds take your best soil away, every time your soil is stirred lovely black organic matter is oxidised to carbon dioxide and water. I suggested to Dave if he could spray off weed in all crop-less places every three weeks as the very first job on his allotment visit, he would soon have good weed control. Kill the perennial weeds and never again let 'annual' weeds seed. Damn it, they even have a knapsack sprayer available in his communal allotment shed. It will only take ten minutes.
|This allotmenteer’s chickweed is winning and every time it is forked out the soil is damaged and a new seedbed is created for new weed seedlings. Prevent the weed seeding by frequent shallow hoeing. Leave it to dessicate and die on the surface|
Weeds between growing crops should of course be regularly hoed. If you must take organic matter away it must go to the compost heap and when rotted returned as a mulch.
|This heavy soil really lacks organic matter. Don’t waste any organic remains that nature provides|
To speed up any conversion from organic-deficient cultivated soil to a no dig system do not be ashamed to gather all the bulky organic matter you can from wherever you can find it. Apply it as a mulch and for most gardeners this will be after composting. My own penchant is to recycle all organic matter directly but for most tidy folk this is a step too far!
I have been discussing with soil scientist friend Peter Williams how to improve damaged clay soil. He agrees that good clay soil structure is mainly about bulky organic matter. He personally might sometimes dig it in. I prefer to leave the job to the worms.
Would a no dig gardener ever dig to improve a damaged clay soil?
Say the soil had a hard plough pan, had been stripped of most of its topsoil to expose sticky xyz clay😱 - 😪apply your own description - and had been generally abused when wet. I might just consider digging. I have previously posted about incorporating newspaper, woody prunings, charcoal, imported soil and gritty materials. I am not as dogmatic as I might seem.
I do want to persuade gardeners that digging is not the natural start of a new gardening project, but even I might be inclined to dig a site ruined by heavy machinery and cultivation. Just once!
Converting a soil that has been completely stripped of it's topsoil down to pure sticky clay is beyond the scope of my article today.
All the allotments on clay soil that I have recently observed, would, with an enlightened no digging policy become highly fertile.
|There are wonderful characters on every allotment. Perhaps this gentleman knows that grassing down is an excellent way to improve soil structure|
And good news for vegetables growers with heavy clay soils…..
Quote from a major technical site for farmers
Minimal cultivation or direct drilling is best carried out on stable soils that maintain their structure throughout the season. Clays, silty clay loams or clay loams are often the best soils for such techniques.
The soils that have most to gain by not digging are clay ones!
So what is so special about Foggathorpe clay?
|A present from Foggathorpe|
Michael announced himself as ‘anonymous’ when he claimed on one of my earlier ‘no dig posts’ that I must have never seen Foggathorpe clay. I soon learned that he cycles past my house every day. He would banter that my methods would not work on his Foggathorpe garden.
When I wanted a picture of clay for today’s post I took the opportunity to ask him and he kindly invited me down. I had some difficulty because when I knocked at number four a lady peeped out of her window, came to the door and said she had never heard of him! After several conversations with local residents - I learnt a lot about Rhea Ferdinand and Manchester United - I discovered number four across the road from number four. Michael explained that there are actually four number fours. Fourggathorpe clay clearly affects the mind.
It had rained heavily the previous night. Michael in triumph showed me his flooded front garden! On the contrary to his supposition, if poor drainage is caused by an impermeable subsoil whether you dig or do not dig is entirely irrelevant. If I had been pugnacious I might have commented that his digging had not done much good.
His attractive back garden was un-flooded. His vegetable garden - the bone of contention - was slightly raised. A very good strategy if your drainage is poor. His dad had formerly used very generous quantities of horse manure and Michael had clearly continued. His black soil looked very fertile and the Kerria in his flower border was twice the height of mine. Clay soils grow wonderful plants!
|Mike reduced his drainage problem by raising his levels - but not in a twee trendy raised bed|
Cathi had warned Michael that I was a fragile old man and he insisted on digging the hole. To my amazement the clay was nearly two foot down.
I always forget to ask the crucial questions. How often does he dig and how deep? In my opinion the more shallow, the more infrequent, so much the better! My guess was once a year and not very deeply (although he did have a very big spade). It won’t apply to Michael but many gardeners who claim to dig just scratch the surface.
He has a very nice soil rich in organic matter. As he dug his hole deeper than he would normally go, the undisturbed soil had a beautiful honeycomb structure. And then we got to the clay!
My impression was that if Michael stopped digging his vegetable garden and controlled his weeds by hoeing - and in any large gaps used glyphosate - that the conversion to the benefits of ‘no dig’ would be immediate.