CF Industries Holdings Inc.’s Donaldsonville nitrogen complex will supply Mosaic Co. with between 600,000 and 800,000 tons of ammonia per year under a long-term deal announced Monday.

The deal means that Mosaic will abandon its plans to build a $700 million ammonia plant at its Faustina phosphate facility in St. James Parish. Mosaic said forgoing the new plant will save the company around $1.1 billion in future capital spending.

CF Industries, with headquarters in Deerfield, Ill., will start supplying the ammonia no later than 2017. The contract is for up to 15 years, and the ammonia price will be based on the price of natural gas delivered to Donaldsonville.

“This agreement strengthens our confidence in the return we expect to generate from our Donaldsonville capacity expansion by providing a steady base demand for ammonia at a price that insulates us from movements in natural gas costs,” said Stephen R. Wilson, CF Industries chairman and chief executive officer.

In November 2012, CF Industries announced plans for a $2.1 billion expansion of its ammonia complex in Donaldsonville. A month later, Mosaic announced plans for a $700 million expansion of the Faustina facility. The Mosaic expansion would have created 53 permanent jobs paying an average of more than $83,000 per year and an estimated 1,400 construction jobs.

The ammonia contract was one of three major announcements by CF Industries and Mosaic. CF Industries is also selling its phosphate mining and manufacturing business to Mosaic for $1.4 billion in cash — which includes $200 million for CF Industries asset retirement trust fund.

The phosphate properties are in Florida. They include the Hardee County Phosphate Rock Mine; the Plant City Phosphate Complex; an ammonia terminal, phosphate warehouse and dock at the Port of Tampa; and the site of the former Bartow Phosphate Complex.

Mosaic said it will also invest around $200 million on marine transport assets to move the ammonia from Louisiana to Florida.

The CF Industries’ facilities currently produce around 2 million tons of phosphate fertilizer per year. Mosaic’s facilities now produce around 9 million tons of phosphate. Mosaic’s phosphate production facilities include the Uncle Sam plant, which lies on the other side of the Mississippi River from the Faustina plant.