Extractable forms of aluminium as affected by gypsum and lime amendments to an acid soil

Abstract

The influence of gypsum or lime + gypsum amendments on various extractable forms of aluminum (Al) in a reconstructed acid soil (plinthic Palexerult) was investigated. The addition of gypsum depolymerized non-hydrolysable carbon (C) and increased the extraction of Al bound to organic matter. The application of gypsum or lime + gypsum lowered the levels of exchangeable Al; also, the low proportion of Al in outflow solutions suggests the immobilization of Al as a solid phase. Except for exchangeable Al, the gypsum amendment increases the proportion of all forms of Al extracted (bound to organic matter, sorbed to, oxalate and citrate) with various selected reagents relative to unamended samples. The amount of Al extracted increases with increase of gypsum added. The gypsum or lime + gypsum amendments increased soil productivity.