This year I did a fertilizer test.I took the sand from my above ground swimming pool that had been filtering the water for 4 years.The sand was dirty and green from algae.I have 16 single stacked tires with the sidewall cut out on one side.Over the years I have been putting composted horse manure and a little plain sand in the tires.I have grown sweet potatoes all my life.This years crop was the best I have ever grown. Or and I have seen grown by anyone. The dirty algae sand had to be the reason.My question is have anyone ever heard of using algae for a soil nutrient?
Thanks
Jack Hickman

They do it in Japan and Hawaii all of the time. What gets used for fertilizer must be cheap and plentiful to become popular. We don't see much use for alge here in the midwest USA.