Speciation of Aluminum in Solution of an Acidic Sandy Soil Amended with Organic Composts

Abstract

The effects of organic amendments (10 and 50 g/kg soil of yard waste, yard + municipal waste, GreenEdge, and synthetic humic acid) on soil chemical properties related to aluminum (Al) phytotoxicity and nutrient availability were evaluated. Compost amendment increased Mehlich 3–extractable calcium (Ca), magnesium (Mg), phosphorus (P), and potassium (K) in the soil by 3.5–260 times. No significant effect of composts on total Al in solution was observed. Organic amendments increased solution pH and decreased the activities of phytotoxic Al species to less than the critical levels, as a result of the formation of aluminate and humic acid–Al complexes. Low‐molecular‐weight organic acids were not effective in forming complexes with Al. Application of composts increased the concentrations of most nutrients in soil solution, suggesting a potential for ameliorating subsoil, but care must be taken to avoid nitrogen (N) and P leaching. Amending composts to acidic soils appears a useful strategy for diminishing Al phytotoxicity potential and improving soil fertility.