PGG Wrightson director Greg Campbell has resigned, days after being appointed chief executive of fertiliser co-operative Ravensdown.

His Ravensdown appointment follows three years at the helm of South Island iwi powerhouse Ngai Tahu's holding company.

Mr Campbell was appointed a PGG Wrightson director last November.

His departure from the rural services company was announced on the NZX this afternoon, without stating a reason.

PGG Wrightson's secretary Julian Daly said: "The board thanks him for his positive contributions and wishes him well in his new role as ceo of Ravensdown."

PGG Wrightson has had a tumultous history since the merger of Pyne Gould Guinness and Wrightson in 2005 – including the disastrous offer for Silver Ferns Farms, which cost the company $50 million, and write-offs from its investments in Uruguay.

Chinese agriculture group Agria came on board at the end of 2009 and eventually took a majority stake.

More recently, Heartland New Zealand bought PGG Wrightson Finance – although PGG retained about $95 million in toxic assets – and troubled shareholder Pyne Gould Corporation has sold most of its holdings.

PGW shares (NZX: PGW) are up 1 cent to 32 cents today, a far cry from the glory days of four years ago, when PGW's shares were worth more than $2.30.