Last year those price increases accelerated and now California wholesalers are telling fertilizer distributors to brace for more rounds of price hikes in the coming weeks and months. Fertilizer prices, which had been stable for many years, now are increasing weekly, sometimes daily. And, some fertilizer products simply aren’t available.

The United States depends on imported ammonia, primarily from Trinidad and Tobago, Russia and the Ukraine, as well as Canada and Venezuela for about half its national needs.

In the past five years, however, U.S. nitrogen production capacity has declined 35 percent, the USDA said. As a result, ammonia imports are rising and landscape managers are increasingly being buffeted by global pricing. Between 2000 and 2006, U.S. ammonia imports jumped 115 percent.

The weak U.S. dollar has eroded buying power for global commodities and materials. Transportation costs for shipping basic fertilizer materials are soaring, particularly fuel costs.

Kathy Mathers, spokeswoman for the Washington, D.C.-based Fertilizer Institute, said, “The Chinese government has just announced that it’s moving from a 35 percent tariff on fertilizer exports to a 135 percent tariff. In other words, China’s two major fertilizer manufacturers will have to pay these export fees before selling them overseas. China is the world’s largest exporter of urea.

“The intent is to keep fertilizer in China for domestic use. China is one of the world’s leading producers of urea, a nitrogen product, and this move will further tighten a global market that’s already operating with a razor-thin supply/demand margin.

“At this point we don’t know how much the impact will be,” Mathers said. “China used to be the world’s largest importer of urea and phosphate, but now they’re one of the world’s largest exporters, based on U.S. Commerce Department numbers.”