Potash prices will come under further pressure at the start of this year, US fertilizer group Mosaic said, amid a "challenging environment".
Mosaic expects to sell potash, a key crop nutrient, for $200-230 a tonne over the first three months of 2016.
This compares to an average selling price of $254 a tonne in the previous three month period.
Canadian broker Raymond James this week saw granular potash prices in the Midwest at $284 a tonne.
Mosaic forecast global potash shipments for 2016 at 58-60m tonnes. This is in line with forecasts of global potash demand made by fertilizer group Agrium this week, but behind the 59-62m tonne forecast made by PotashCorp on Tuesday.
Total sales volumes for the Mosaic's potash segment are seen at 1.5-1.9m tonnes for the first quarter of 2016, down from 2.0m tonnes over the same period last year.
Mosaics potash sales are falling, after a decision to reduce volumes in the face of low prices.
Full year potash sales volumes were seen at 7.5-8.5m tonnes.
Phosphate prices will also fall, Mosaic said.
Phosphate prices were seen at $350-370 a tonne over the first three months of this year, down from $410 a tonne over the last three months of 2015.
Raymond James saw diammonium phosphate prices in Florida ports priced at $355 a tonne this week.
Mosaic saw 2016 global phosphate shipments at 65-67m tonnes.
Mosaic forecast sales volumes for its phosphates segment down to 1.8-2.2m tonnes in the first three months of 2016, down from 2.3m tonnes in the same period last year.
Full year sales were seen at 9-10m tonnes.
The news came as Mosaic reported a sharp drop in profits, albeit by less than analysts had forecast.
Mosaic reported a profit of $155.0m in the three months to December 31, down 57% year-on-year.
Adjusted earnings were down 39%, at 53 cents a share, ahead of the 44 cents a share forecast by analysts.
Sales were down 9%, at $2.16bn. This is better than the $1.93bn projected by analysts.
Mosaic's potash sales in three months to December 31 were down 25% year-on-year, to $572m.
Phosphate sales fell by 17% to $1.0bn.
The company managed to cut its cost of production by 16% over 2015, helped by the weaker Canadian dollar and facility closures.
By William Clarke