Forms of magnesium in soil as influenced by added magnesium sources under submerged condition

Abstract

A laboratory incubation study was carried out using two acid rice soils of Kerala under submerged condition for 180 days. The soil samples drawn at regular intervals were analysed for chemical forms of Mg. The insoluble Mg fractions dominated over the soluble ones. Acid soluble Mg and mineral Mg together constituted about 74.03 per cent of the total Mg content. Ammonium acetate extractable Mg of the soils was 19.09 per cent. The content of organic complexed Mg was very low and that of water soluble Mg was practically nil. Total Mg content as well as the content of various Mg fractions was higher in karappadam soil than in the laterite soil. The soluble Mg fractions were higher in samples supplied with magnesium sulphate while the insoluble fractions were higher in samples supplied with carbonate forms of Mg. The difference between the Mg levels tried in this experiment became conspicuous only under conditions of prolonged submergence.