Contact the "Gravel" company located in Gdansk
gravel.pl/en/kontakt/
They had in their offer the chernozem you needed:
For sale sifted chernozem for 25 zł / m3 gross
Fertile land (top soil with small amount of sand) is ideal for creating gardens, parks, lawns, reclamation of brownfield sites.
When ordering in bulk min. 12 m3 delivery in the Tricity - FREE !!
In other cases, the price of transport to be arranged.
gravel.oferteo.pl/czarnoziem-siany/63781
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