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.
