A lucrative deal to export potash, a crop fertilizer, at the Port of Vancouver is off after more than three years of negotiations, including a preliminary agreement, failed to secure a final lease accord. The port said Friday it and BHP Billiton have allowed an agreement that gave the Australian mining giant exclusive rights to property at Terminal 5 to expire as of June 16. However, the port said, it and the company remain open to keep talking about the possibility of building a potash export operation at Terminal 5 in the future. "We're confident that we can find a new tenant for Terminal 5 in the near future," Todd Coleman, the port's executive director, said in a news release. "And because our relationship with BHP Billiton remains positive, we're in a strong position to work with them in the future." In an emailed statement to the Columbian, Bronwyn Wilkinson, a spokeswoman for BHP Billiton, said the company remains confident the port's Terminal 5 "would meet our needs if a viable alternative rail solution can be identified. However, we are taking this opportunity to explore all alternative logistics options."