Preliminary results—which Arriaga will present at a Soil Science Society of America conference this month—suggest gypsum is helping keep phosphorous in Johnson’s soils.

White phosphorous munitions are used to create smokescreens to obscure the battlefield, but it is not listed as a chemical weapon, according to international treaties.

This year it has already been hit with a rocket, phosphorous gas and the bunker-buster bomb, he said.