Abstract To mobilize sparingly available phosphorus (P) in the rhizosphere. many plant species secrete malate to release P sorbed onto (hydr)oxides of aluminum and iron (Fe). In the presence of Fe. malate can provoke Fe over-accumulation in the root apoplast. https://www.jmannino.com/best-grab-Kelway-SST-Salinity-Tester-top-mega/