Browsing by Author "Krishnakumar, A K"

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    Chemical properties of the Poonthalpadam soils of Kerala
    (Kerala Agricultural University, 1986) Krishnakumar, A K; Koshy, M M
    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.
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    Physical characteristics of the poonthalpadam soils of Kerala
    (Kerala Agricultural University, 1985) Krishnakumar, A K; Koshy, M M
    An appraisal of tha physical characteristics of the Poonthalpadam soils reveals that the texture of the profile samples varies from sandy clay to clay. The highest clay content is found to be in the surface layers which may be either due To impeded drainage which does not permit cJay migration or due to deposition of clay by flood waters on to the surface of the original soil. The apparent specific gravity ranges from 1 .20 to 1 .80 and the absolute specific gravity varies from 2.25 and 2.51 . There exists a negative correlation between clay content and apparent specific gravity. The porespace as well as volume of expansion show a decrease down the profile except in the profiles from Valiavallampathy and Kuttippallam. The upper and the lower plastic limit and sticky point moisture are found to be the highest in the surface layer of the profiles. These limits are of importance to the tillage operation since plastic limit represents the minimum moisture percentage at which the soil can be puddled and these fimitsare affected by ctay content, nature of clay minerals, organic matter and nature of exchangeable cations. Improving the physical condition of these soils would result in increased productivity of these soils.