To Dig or Not to Dig; That Is the Question

by frankbeswick

There is currently a controversy in gardening about the no-dig method.

"When Adam delved..." begins an English poem from the seventeenth century. Delving was a term used in this context for digging. Adam was traditionally seen as a tiller of the land, and so the use of the term delved indicates how digging is so strongly associated with gardening. But in recent years there has arisen a no-dig school of gardening. This theory regards digging and ploughing as harmful to the soil and has found favour with some green activists.But is no-dig an absolute rule or a body of ideas to take into consideration when planning our garden strategies?

Image courtesy of Hans

Digging in the Garden

I have just taken over an extra half plot of land to augment my existing allotment; and my eldest son Andrew and I are in the process of preparing it for  cultivation next Spring [2017.] The reason behind this extra work is that I now have three homes to feed with fruit and vegetables. There is my own home, Andrew's young family and now Peter, son number two, is married and settled in Manchester. His wife is a vegetarian, so vegetables form a large part of their diet.So there is added demand on my gardening. I don't mind, for I have the time to garden, especially as I am winding up my tuition business and will have ended it by June. So more time for the allotment!

The plot was held by a young couple who had a young family, which they home educate. Lovely people, but they could not keep up the demands of a plot while rearing a family and the husband is working difficult hours. They have done a pretty good job of being rid of perennial weeds, but the ground surface show signs that it has been allowed to become overgrown with tussocky grass. So Andrew and I have begun the clearing process. Andrew took off much of the surface vegetation while I trimmed the bushes in the flower bed. Then we both set about digging, turning over the clods and extracting couch grass roots. This is  troublesome weed species that must be rooted out.  I am glad of the help of  a younger man, and we are going to get help from my two daughters-in-law in Spring, but they have already decided that they want to help with herbs and flowers. 

So without some digging no gardening can take place. Vegetables like a good, fine tilth, a soil turned into a fine crumb structure, and there they thrive. Furthermore, if you grow root crops such as potatoes you need to dig them out, and the same goes for carrots and parsnips. Furthermore, hoeing has a seriously important place in creating tilth, but hoeing disturbs only the surface and does not go as deep as digging does. In fact some digging can go down to two spades or more in depth,Sometimes you need to do this to eliminate pernicious weeds, such as Japanese knotweed.  

Trees and rhubarb, both involve occasional digging. Every five years or so you need to lift and divide your rhubarb crowns to ensure continued vigour. So you must dig them up and break them into two or more pieces. If you plant trees you need to dig a hole for them to go into. So gardeners cannot avoid digging sometimes.   

The No-dig Method

Charles Dowding is an expert gardener whose beautifully tilled plot lies in Dorset in South West England. For many years he has encouraged the no-dig theory of organic gardening, for he believes that digging lessens the soil's fertility. His plot has been no-dig for fourteen years.  Recently in Country Smallholding magazine [January 2017, which I received in December]  he published the results of a study in which he compared dug beds with undug beds. The study has been carried out over ten years, but in this magazine we got one year's results. For the sake of scientific accuracy he ensured that both beds were equally fertilized with compost, manure and rock dust. Charles does not use artificial fertilizers [ a view with which I personally agree] because they damage the soil fungi which do so much to enhance fertility. 

Taking the weight of vegetables produced during April to October 2016 the dug bed produced 98.86 kilograms of vegetables, while the un-dug bed produced 108.62 kilograms. But within these figures there is detail about specific vegetables.  Coriander produced exactly the same amounts, and shallots, peas [Delikett] , potato [Swift] and carrots were more productive in dug beds. But many other vegetables were more productive in the undug bed. Carrots sown between lettuce seemed more productive in the dug bed. But significant differences in favour of the undug beds were observed. These differences were in successional vegetables, these being beetroot after cabbage [dug 6.14kg to undug 6.85] kale after  beetroot [4.47 to 7.17] and dwarf bean Cupidon after cabbage [2.80-2.93. Both cabbage and kale are the same species, so maybe there are problems with the members of the Brassica family [to which they belong] in that the dug soil needs more time to recover from them than undug soil does. 

Charles notes other advantages to undug beds. They seem to retain water better than dug beds, probably due to their stronger soil structure. He believes that dug soil can produce a hard "pan" layer on the surface that slows down water absorption, yet it lets water drain away quicker when it gets in. He also notes that plants are better anchored against wind in undug soil.The dug plots seem more susceptible to weed growth later in the year than the undug plot does.  

He cites Professor Elaine Ingham who believes that digging and ploughing break up the networks of fungi in the soil that do so much for its fertility. Soil fungi, known as mycorrhizal fungi, dwell in symbiosis with plants, exchanging sugars, mineral salts and water with them to  their mutual benefit.  Digging and ploughing, she believes, also cause loss of carbon from the soil into  the atmosphere, contributing to global warming and soil loss, a kind of double trouble.

 

Moderation in all Things.

So what should we do about digging. To dig or not to dig is not the question, for we should be asking when and how much to dig. It is clear that Charles has a case, and he can make it on good scientific grounds. However, he must hoe the topsoil very well to produce beds with such a beautiful soil as he has. He admits to hoeing the soil and does not regard doing so as being in contravention to his no dig principles. But hoeing and digging are related activities, differing only in that one has a lighter impact than the other, for both break up the soil. 

It seems to me that there are gardening tasks that require digging, such as dividing your rhubarb crowns, which is a  process that is important for enhancing their vigour, but which involves digging them up. However, deep digging should be done but rarely and only for a specific purpose.  We do not need to dig every bed every year, for digging is not something to be done for its own sake. A simple hoeing of the soil and an overlay of compost might be sufficient in many cases. But a dug soil loses some of its cohesion, and so artificial fertilizers applied to it might be more easily washed  away than they would be in an undug bed. This suggests that the best materials for augmenting fertility in dug beds must be manure and compost, the latter of which holds nutrients in non-soluble form and so prevents them from being washed away.

We need to avoid excessively strict adherence to rules in gardening, and most rules may be better regarded as guidelines rather than rigid enactments that one cannot contravene.Certain pernicious weeds, such as couch grass, which tends to take over if left alone, have to be dug out. Moderation in all things!

Updated: 12/12/2016, frankbeswick
 
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frankbeswick on 03/03/2017

That sounds like a well-tilled garden! I too have used weed matting. I have covered all the paths with it, and on the beds that I am using for salads I am going to plant seedlings through slits in the matting. The matting worked for my paths, which in the last rain-soaked year that we had in Britain were invaded by couch grass and caused me much trouble. The bad weather caused my herb beds to be weed-infested, so what I did was to lay a large fabric mat across the bed and place my planters on top of it. Thus the weeds cannot force their way up through the herbs, as they did last year, meaning that I could not destroy the weeds without killing the herbs.

Thanks for the tweet. I am not on Twitter, so I cannot tweet.

katiem2 on 03/03/2017

Good food for thought. I have the same garden plot I have used for the past twenty years. I have it as close to organic as possible. I till it every spring although lost year I put down weed matting between rows and it work wonderfully because I lightly refilled the rows to loosen up the soil, it worked the matting stuck well I wet it with the garden hose to help out. anyway the weed matting is still firm in place and free of anything growing so I think I am going to leave it and till around it after all if it ain't broke... gonna tweet and share this fine gardening spot

frankbeswick on 12/14/2016

To confirm my view that some digging, at least initially, is necessary. The new half plot that I have taken over has not been properly dug for several years, not since a very industrious Irishman left us. Since then it has been in inadequate hands, and the ground is simply not fit for planting.I have been working hard to clear the grassy surface and dig the ground over. With the wet weather that we are having at present [December] the ground is very hard to dig and heavy to work.

We will get it right, but I have also found that it is low on humus, the black material that makes for good soil,so I am going to have to apply compost and manure, lots of it. Working undug soil in December was very arduous.

blackspanielgallery on 12/13/2016

I must confess that when I started reading I was expecting hydroponics, or some other such practice. Nicely done. And I learned there are other ways to not dig than use water.

frankbeswick on 12/12/2016

It is interesting that you have never dug, but did not refrain from digging because of a specific theoretical position. But you seem to be taking the pragmatic approach that is so necessary in gardening.

dustytoes on 12/12/2016

I have no gardens yet, and it's like suffocating without a garden to work in! This is an interesting read. All I ever did was add compost and use the hoe. I've never dug for no reason in my gardens. So I suppose I am a "no dig" gardener. But, like you say, sometimes you have to dig, for potatoes, rhubarb and such.

frankbeswick on 12/12/2016

Thanks, Sheilamarie. We have decided to reserve the new plot [plot 39R] for staples, such as potatoes and onions, which we will normally want in bulk. Andrew's wife, with two children to feed, always wants potatoes; Peter, who is keen on cooking, uses many pumpkins, so some of those can be grown on plot 39R. My old plot [plot 7] will be used for a variety of crops as it is now. The two daughters-in-law have ambitions. Andrew's wife is into jam making, so she can use the apples, and Peter's wife is into herbs.

sheilamarie on 12/11/2016

Interesting discussion, Frank. I hope your garden produces a lot this year. We are trying to up our garden production as well.

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