Hi all,
cheers Darrel
It is a combination of factors. Phosphorus is highly mobile within the plant, so the plant can continually shuffle it to the newer leaves. There is also the possibility that PO4--- may become available within the substrate from "insoluble" reserves. How large that reserve would be dependent <"upon various parameters">.does it take "a while" before plants show a phosphate deficiency? Is this because aquarium plants can store a reserve of phosphate?
cheers Darrel