Hi digWinstanley
First of all may I suggest a name change to no-digWinstanley 🙂
Sorry, but I put this up before reading your reply. It would be good to hear what Charles has to say.
If I had a 112sqm plot I would calculate, using 1.2m beds and 0.6m paths, that the area needing a compost cover would be 75sqm. Using Charles’ minimum depth of 3cm, I would need 2.25cum. The bags work out at £10 for 0.32 cum so I would need £72 worth.
I would also, like you, use my veg and fruit scraps from home, cardboard from home and veg debris from the plot to build a compost heap to supplement, admittedly by a small amount, my 3cm of bought compost.
I would also consider growing green manure to bulk up the compost bin, either where there are short season crops or in dedicated beds. An Exmouth plot holder conducted an experiment over a 30 year period and was able to sustain a no-dig approach, without outside inputs, using one third of his land for green manure crops to ‘feed’ the rest of the plot. Although this reduced his growing area he was able to use his growing areas more intensively.
You mention 3 things that put people off no-dig.
Relative costs and resources: most of my neighbours, all diggers, either buy in FYM or lots of fertilizer. The latter group also uses lots of water on their crops as there is little in the ground to hold onto the rainfall. We are on Pebble Beds, not as free draining as Bagshot Sands, but with little to hold on to moisture. I think some also spend lots of money on weedkillers and insecticides, equipment for digging, rotavating and so on. I doubt that the diggers spend much less overall than the no-diggers. The cost of the compost is only one item in the equation. Of course if you go in for copper tools like Charles the argument may fall flat!
Time: I have no doubt that the time involved in digging and composting is far greater than no-digging and composting. Even digging without adding compost is far more time consuming. I have also no doubt that there is less time needed for weeding and watering using a no-dig approach. The saving of time and making the work less physically arduous are two arguments put forward by Charles.
I think there are other things that put people off no-dig:
The strongly voiced opinions of some plot holders who extol the virtues of digging and decry other approaches.
Incorrect information given by well-respected expert/professional gardeners, as in the case of Christine on GQT
Advice given in many books and articles about the NEED to dig.
A misunderstanding of the distinction between getting rid of weeds and feeding the soil. I think that many people see Charles’ instant raised beds on meadow grass with 15cm of compost and then they do the calculation for their allotment and end up with scary figures. They do not see the sections on adding minimal amounts of compost on clean soil which has been cleaned by traditional methods or light suppressing mypex before going no-dig.
The main difficulty I have with no-dig is that I actually like digging! 🙂
Best wishes
John