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Top soil v compost

mandyroberts99mandyroberts99 Posts: 235
in The potting shed
I am planting a new bed which I am digging at the moment. It is on a slope and I have built a retaining wall so will level it out to reduce the slope. I need more 'soil' and have rotted manure which I can use but will need more. As multi-purpose compost is cheaper than top soil why do you use top soil in preference to compost?
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  • Hostafan1Hostafan1 Posts: 34,889
    I'd go with top soil. MPC doesn't have much "guts" to it and oxidizes over time.
    Devon.
  • Lizzie27Lizzie27 Posts: 12,494
    I agree with Hostafan but we did fill our large raised beds with a good mix of manure, home made compost, top soil and MPC to keep the cost down, which seemed to work well. If you can get John Innes 3 MPC at a reasonable price, it's the nearest mix to top soil.
    North East Somerset - Clay soil over limestone
  • mandyroberts99mandyroberts99 Posts: 235
    Sorry my calculations were flawed. Top soil is cheaper than compost but I'd still like to know when you use which? I need about 500l
  • Hostafan1Hostafan1 Posts: 34,889
    I'd only use MPC in pots/ containers not " in the ground" 
    Devon.
  • mandyroberts99mandyroberts99 Posts: 235
    Hostafan1 said:
    I'd only use MPC in pots/ containers not " in the ground" 
    But why?
  • Hostafan1Hostafan1 Posts: 34,889
    mandyroberts99 said:
    Hostafan1 said:
    I'd only use MPC in pots/ containers not " in the ground" 
    But why?
    It oxidises, so in time the "ground" will shrink, not a problem in pots, which tend to be more short term. 
    Devon.
  • mandyroberts99mandyroberts99 Posts: 235
    mandyroberts99 said:
    Hostafan1 said:
    I'd only use MPC in pots/ containers not " in the ground" 
    But why?
    Just saw your original reply above - thanks
  • Lizzie27Lizzie27 Posts: 12,494
    I don't know where you get your MPC from @pansyface but the stuff I buy doesn't contain any of the things you describe and it's rather a misleading statement to say that 'green waste' rots down to nothing. Green waste from Council tips is nothing more than grass cuttings, leaves, old wood and branches etc, which is heat treated to break it down quicker into 'compost', essentially the same process as what happens to wood litter on a forest floor. It's a good soil improver.
    North East Somerset - Clay soil over limestone
  • Mike AllenMike Allen Posts: 208
    IMO.  Each to their own.  Top soil, is self explanatory.  It so often consists of soil that most gardeners would say, was that of double digging.  Joe Brown is digging out for the foundations of a bungalow extension.  He wants to get shot of the soil and make a few bob, rather than pay a contractor to dump it for him.  So the top soil can be good or total muck.   There is, if you so desire.  Steralised top soil.  That's a differenet matter.

    Now to compost.  This can be basically, your kitchen waste, the scrubs from allottment crops etc and what is now termed, recyclable material.

    For the latter.  When commercially produced, the matter, has been specially treated.  This in a way has speeded up the decaying process etc.  Then chemical and scientific tests are made, and the bulk/mass is examinined for it's horticultural benefits, this include it's pH values and many other biological benefits.  Chemical additives are duly added.  Despite perhaps what some of us might call rubbish has been included.  This is recycling.  I obtained a ton of top soil, and filled my former weed free garden with, heaven knows what.  I use MPC, JA Bowers in th GH, and get high results.  Spent compost is used for potting up. Finally on clear out day.  Compost from wherever is used to bulk up the garden..  After all said and done.  Originally everything came out of the ground.  So we are simply returning it.
  • FairygirlFairygirl Posts: 55,117
    Hi @mandyroberts99. Don't overthink it. A mix of mainly soil, a good dollop of manure, and some compost [home produced and shop bought] will allow you to grow most things. You'll have to accept that it can be pricey, when starting out, to fill it. If you have any turf from elsewhere, you can put that in the bottom too, which will give a good base. 
    Avoid too much shop bought compost, for the reasons initially stated, and assuming the bed is open to the ground, you'll need to top it up on an annual basis anyway, as the soil in the bed will naturally drop down into that.
    Enjoy using it.  :)
    It's a place where beautiful isn't enough of a word....



    I live in west central Scotland - not where that photo is...
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