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What is this in the soil? Bone meal? Perlite?

I am in the process of digging over some ground that has not been touched since I bought th house from the previous owner who a keen vegetable gardener.

I am finding clumps of a white material, which seems unaffected by water but crumbles very readily when touched. I initially wondered if it might be bone meal or perlite, but I have not been able to find any pictures online which are a good match.

I just wondered if anybody here had any thoughts on it. Any help would be much appreciated.



  • LG_LG_ SE LondonPosts: 4,049
    I don't know either, but I would like to! I dug a load of that my sister's garden. Definitely not fungal, definitely not chalk - but what on earth is it?
    'If you have a garden and a library, you have everything you need.'
    - Cicero
  • BorderlineBorderline Posts: 4,687
    It could be lime added to the soil. Some gardeners add lime to soil to increase PH levels, especially on acidic soils.
  • LiriodendronLiriodendron Scariff, County Clare, IrelandPosts: 7,871
    It does look like lime... often added to soil which isn't naturally alkaline, to protect against clubroot in brassicas.
    "The one who plants trees, knowing that he will never sit in their shade, has at least started to understand the meaning of life."  Rabindranath Tagore
  • Thank you for all the comments. I will try putting some vinegar on it in the morning, I will also test the pH of the soil.
  • I put some vinegar on today and there was no reaction at all. So the mystery continues :)
  • Lizzie27Lizzie27 SomersetPosts: 10,531
    Could it be crumbled polystyrene?  It seems unlikely but if it floats in water, it might be but I can't think why the previous gardener didn't pick it out his soil. It's sometimes used to aid drainage or partially fill very large pots to save on compost.
  • edited March 2020
    Thanks for the responses. It is definitely not paper or polystyrene.

    The house is 1950s and was occupied by the same avid gardener since the 1960s.

    It is in one location, all within about 2 square metres and not more than a foot deep, next to a rear fence and a patch of rhubarb (not in patch but just next to it).

    Given how much the previous occupier gardened, and presumably disturbed the soil, I would expect that it has only been there a few years at most. The biggest chunk I found was about the size of a cricket ball.

    I wondered if its proximity to the fence (concrete posts) I wondered if it might be left oevr from construction, but I think that it is very unlikely. I think it is almost certainly something which has been added to the soil intentionally.

    The house is in Worcestershire and has clay below the top soil. The top soil seems to vary across the garden, probably due to landscaping in the past, but I reckon about a foot in most places (although I'm not that experienced in judging when top soil ends and sub soil begins).
  • BobTheGardenerBobTheGardener Leicestershire, UKPosts: 11,391
    Gypsum?  That is often added to clay soil to help break it up.  The previous gardener may have stored some in that spot.
    A trowel in the hand is worth a thousand lost under a bush.
  • BenCottoBenCotto RutlandPosts: 4,049
  • Lizzie27Lizzie27 SomersetPosts: 10,531
    I've never seen any but gypsum could well be likely on a clay soil. Maybe a bag split in that particular spot and the paper covering just rotted.
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