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Soil cultivation (probably a stupid question!)

Evening everyone. So just out of interest, when incorporating organic matter into the garden, why is it buried? For example single digging has you dig a trench then backfill with farmyard manure for example, then on to the next trench etc. Surely this just means that the manure sits below the soil instead of being mixed in?

many thanks :smile:


  • BobTheGardenerBobTheGardener Posts: 11,391
    edited January 2021
    Double-digging is rarely used and is usually only done when preparing new ground, or breaking-up a hard layer such as an iron pan.  Organic matter will often be added just because it is easy to do so when using this digging method and will give the soil better structure and an immediate boost to fertility, so hungry plants can be planted straight away.
    In nature, all organic matter falls on the surface and is taken down by worms and other soil organisms, so to have the most natural (but still very fertile) soil (after the initial preparation of a new area), put organic matter down only as a mulch or when planting and let nature do what it has always done.
    In other words, adding manure when digging is a way to shortcut the period before you can start growing things compared to only using a mulch (which would take 4-5 years before the soil was deeply fertile, if mulching was the only method used on an uncultivated piece of bare ground.)
    Nobody really does neat double-digging with even layers of manure like in the books, I can assure you, so it gets pretty well mixed-in as you go! :D
    A trowel in the hand is worth a thousand lost under a bush.
  • How do you get all this knowledge? :smile: and many thanks for your advice! The soil I’m adding the manure to was and probably still is practically powdery. I wonder if it is better to rake it in, consolidate it then rake over again to get a level surface. The photo shows the soil before
  • JennyJJennyJ Posts: 8,882
    That looks a lot like my soil does in summer when it's dry! I mulch with compost between existing plants when I can, and fork in compost when I'm preparing an area for new planting. No double-digging here, but if I dig a planting hole and the soil seems hard at the base, I stick the fork in and wiggle it about to break up any pan.
    Doncaster, South Yorkshire. Soil type: sandy, well-drained
  • Is that soil inside your greenhouse?  If so, that is rather different, and you can't rely on nature doing things for you.  Having soil borders in a greenhouse is a double-edged sword;  On the positive side, things need much less feeding and especially watering than using pots, but the downsides are pests and diseases build-up (I have to replace the top 6 inches of soil in my GH borders every 3 years, which is quite a job!)
    In your case I would spread a 2" layer of manure over them, dig that in to about 8" deep, then another layer of manure on top, fork over gently and then rake level.  Remove every bit of old root etc that you come across while working the soil.
    As I get older, I'm finding the GH border soil replacement/upkeep is too much like hard work, so I'm planning on giving up soil GH borders and will be laying gravel on them and growing things in pots instead.
    A trowel in the hand is worth a thousand lost under a bush.
  • Thank you for the information and advice. Looks like I may need to get some more manure than! Maybe much later. Wouldn’t that be too much manure though? I’ve put in three bags worth so far which I think are 20 litre bags.
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