Chemical properties of the Poonthalpadam soils of Kerala

Abstract

An investigation on the chemical properties of Poonthalpadam soils of Kerala shows that these soils have a pH range of 6.5—8.4. .The total nitrogen content is low in most of the profiles studied. While the level of total P205 is found to be satisfactory, the available phosphorus content is low probably due to the fact that the P is present in combination with calcium and clay in rather unavailable forms. Tne level of available potassium also is unsatisfactory which warrants potash fertilization. Cation exchange studies reveal that calcium is the predominant cation and 67 percent of the CEC is satisfied by the divalent cations, calcium and magnesium. Sodium is also found to be present in the exchangeable form and in some cases its content exceeded that of magnesium. The poor physical characteristics can be attributed to the presence of sodium, which causes dispersion of clay, and also to the high water table. Organic matter is found to be higher in the surface layers because of the illdrained condition and the wide C/N ratio noticed in some profile samples is possibly due to loss of nitrogen by denitrification and persistence of organic matter due to anaerobic condition. Improvement of the drainage and ameliorative measures for alkalinity are necessary for the reclamation of these soils.