used potting compost

[Jane WildingMember]

I’m hoping to pick the brains of anyone with a scientific background!  I have a polytunnel on a community project site which has no topsoil other than what we can import or create.  The site was formerly a commercial pot-plant nursery, so everything was grown in pots on mypex.  But we have a potentially fantastic resource – a huge pile of overgrown, used commercial potting compost, dumped at one end of the site.  We are strictly organic, so haven’t been using this on our beds, but given that we have to import (and usually buy) any topsoil that comes in, and we’re greatly expanding this year, it seems a great waste not to use this.  It’s peat based of course, which we wouldn’t normally use, and has those little yellow beads of plant food in it.  It’s been dumped there for at least 3 years, since that’s when the commercial firm left the site.  Does anyone know the compostition of the yellow beads, how long they last and why they haven’t degraded yet?  I would really like to use this great resource but we don’t want chemical fertilisers in our tunnels.

many thanks for any info!

Jane

[zufParticipant]

For me it not a concern of chemical  fertilizers so much. What you are looking for in this potting soils are heavy metals, that’s your reall concern. And they are not in those beads, but are in general present in proccess of creating potting soil, compost etc. They get materials from sewege and elsewhere. Not always the case, but here in Slovenia we have this a lot, when potting soil is imported. You have no other option than taking that soil on tests. Than you can be totally sure.

[charlesModerator]

Part of being organic is to recycle waste. I would be surprised if there is any fertiliser left in those granules, I think they are designed to last months not years. Was any of the weed growth on top looking fertilised?!

They must be little plastic beads, is that what they seem like? Yes one would not want them in beds but when it means using a big resource which is on site, I would.

Good luck with your expansion.

[Author]

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