Phosphate builds up in soil, converted to insoluble forms. Most applied phosphate isn't absorbed by plants. So "regenerative agriculture" could actually make

Phosphate builds up in soil, converted to insoluble forms. Most applied phosphate isn't absorbed by plants. So "regenerative agriculture" could actually make sense if there are ways of tapping into this phosphate bank, say by encouraging the growth of phosphate mobilizing microorganisms. One issue with phosphate ore is contamination with undesirable elements, like cadmium and also uranium and its decay products, like radium. The waste stream from sulfuric acid treatment of the ores is radon-emitting gypsum. Sulfuric acid itself may become limiting once we're off fossil fuels, since almost all of it is currently produced by oxidation of sulfur extracted in the desulfurization of oil and gas.