Minnesota does not allow use/sale of phosphorus-containing lawn fertilizer, to keep it out of lakes/rivers for exactly this reason (preventing algae). The middle number in the N-P-K analysis is always 0.
Fools ignore complexity. Pragmatists suffer it. Some can avoid it. Geniuses remove it. -- Perlis's Programming Proverb #58, SIGPLAN Notices, Sept. 1982