A group that promotes trade is urging Iowa farmers to call the White House and speak out against tariffs on imported phosphorus.

Florida, Morocco and Russia are the primary sources of the mineral and Kent Kaiser of the Trade Alliance to Promote Prosperity says a Florida company has asked the Trump Administration to impose tariffs on phosphorous shipped into the U.S.

“We oppose this because it would increase costs for farmers and, ultimately, for consumers,” Kaiser says. “…We estimate it would be about $72 million for Iowa corn growers alone.”

Phosphate fertilizer is spread on 60% of U.S. cropland planted with corn, soybeans, sugar beets, cotton and fruits and vegetables. Kaiser says it’s used by home gardeners as well.

“If you go out and buy fertilizer for your garden, you’ll see there are three number on there and they are called N, P and K. You might see 10-10-20. It’s that middle number — the P — that stands for phosphorous,” Kaiser says, “so it’s actually much more common than one might realize.”

Officials in the U.S. Commerce Department announced they’ll make a preliminary recommendation on the proposed tariff on imported phosphorus as early as this week. The Mosaic Company, based in Tampa, Florida, is the largest producer of phosphorus in the United States and is seeking the tariff on imports from Morocco and Russia.

The main ingredients in commercial fertilizers are nitrogen, phosphorus and potassium. Phosphorus assists a plant’s development and ability to use and store energy.