Billionaire Gina Rinehart has made a $US300 million ($395 million) play in the fertiliser industry, buying into London-listed Sirius Minerals in a deal that will include the construction of a mine in Yorkshire.

Mrs Rinehart's deal will see her Hancock Prospecting buy $US50 million of Sirius shares, a 5 per cent royalty stream of the first 13 megatonnes, and 1 per cent thereafter, of fertiliser produced by the mine annually and the right to purchase up to 20,000 tonnes of product each year for use across her expanding Australian agricultural holdings.