SASKATOON -- Strong growth in global food demand combined with promising harvest and fertilizing plans in the United States and elsewhere around the world bode well for Nutrien Ltd. going into 2021, chief executive Chuck Magro says.

"While most companies and industries have seen an impact to their businesses due to the COVID-19 pandemic, agriculture has been more resilient than most and is now demonstrating real strength as we head into 2021," he said on a Tuesday conference call to discuss the company's financial results.

"This underscores the consistent growth in global food demand even through a global economic and health crisis."

Demand for fall fertilizer application in the U.S. is up as the harvest is well ahead of schedule and crop prices are rising on strong demand and lower production, he said, adding affordability is high for potash and nitrogen fertilizers.

Meanwhile, strong demand for fertilizer is being seen in China, which is growing more feed grain as it rebuilds its hog herds after the African swine fever epidemic, as well as in Brazil and Australia, he said.

The Saskatoon-based company, which reports its results in U.S. dollars, is less optimistic about long-term price prospects for phosphate fertilizers, however, and announced an $823-million writedown in the value of that business related mainly to its two production facilities in Florida and South Carolina.

The impairment charge resulted in a third-quarter net loss of US$587 million, compared with net earnings of US$141 million in the same three months a year ago, while adjusted earnings before interest, taxation, depreciation and amortization fell 15 per cent to US$670 million from US$787 million.

Nutrien reported sales in the three months ended Sept. 30 of US$4.2 billion, up from US$4.17 billion in the year-earlier period.

Scotiabank analyst Ben Isaacson rated Nutrien's report as "slightly negative" due to an adjusted income miss and lower-than-expected nitrogen sales and retail margins, balanced by higher-than-forecast revenue, earnings per share and potash sales volumes.

Despite lower margins in the third quarter due to fewer insecticide and fungicide applications in the U.S., Nutrien's retail operations delivered 13 per cent higher adjusted earnings in the first nine months of 2020 as total sales through its digital platform, driven by the pandemic lockdowns, exceeded US$1 billion.

That's more than double the company's goal of US$500 million for the year and accounted for 43 per cent of North American sales of products available for purchase online, the company said.

"I think it's early days, but it's an avenue for us to drive organic growth as well," said Mike Frank, executive vice-president and CEO of retail on the call, adding online sales of farm products and services are proving to be more efficient for both growers and Nutrien staff.

Potash sales jumped 13 per cent to 3.7 million tonnes in the third quarter compared to 3.3 million tonnes in the same period last year, but adjusted earnings were down due to lower prices.

The contract to deliver Saskatchewan potash to China expired at the end of October, Magro said, adding rising demand there means Canpotex, the marketing company it co-owns with Mosaic Co., is well positioned to negotiate higher prices in the next contract.