Browsing by Author "Thomas Varghese"

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Classification of wet land soil of Kerala for placement in soil taxonomy
(Department of Soil Science and Agricultural Chemistry,College of Horticulture, Vellanikkara, 1993) Unnikrishnan, S; Thomas Varghese
Nine soil pedons, seven from natural wet lands and two from man made wet lands were studied. The locations were Vellayani (Natural/fresh water Kayal), Karamana (Manmade valley bottom), Thakazhi (Natural/Kayal),Nedumudi (Natural/Karappadam),D-block (Natural/Kayal), Njrackkal (Natural/Pokkali), Anthikad/(Nztural Kole) Pattambi (Manmade valley bottom) and Pazhayangadi (Natural/Kaipad), Pedons were described systematically and subjected physico chemical & mineralogical analysis. From the studies it was revealed that the wet lands of the State in general had immature soil morphology. Characteristics of the soils were mainly attributed to the parent materials. Absense of characteristic horizonation and diagnostic surface or subsurface horizons indicated that these soils were young. Three soil orders namely Entisols, (Vellayani, Karamana, Kari, Kayal & Kaipad pedons) Inceptisols (Karappadam, pokkali and kole pedons) and Ultisoils (Pattambi) dominated the wet land pedons analysed. Isohyperthermic temperature and aquic moisture regimes were dominant in all pedons. Saline acid and Sulphidic soils identified in conventional terminology could be confirmed in the present study also. The derivation of terminology for the wet land soils of Kerala, based on the assumptions of USDA-SCS helps to categorise these soils according to soil taxonomy, the nomenclature in vogue.
Evaluation of acidity parameters in wetland soils of Kerala in relation to nutrient availability
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1995) Usha, P B; Thomas Varghese
Impact of eucalyptus and acacia plantations on soil properties in different pedogenic environments in Kerala
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1989) Byju, G; Thomas Varghese
Eucalyptus tereticornis and Acacia Auriculiformis are two important exotic tree species introduced into our environment through National Social Forestry programme. These two species are said to have many qualities which qualify them for inclusion under the social forestry programme. These fast growing tree species have the unique capability of surviving and regulating their growth to prevailing growth factors. But environmentalists in India and abroad have questioned the feasibility of bringing fertile lands under these exotic species which they claim to have deleterious impact on soil properties, hydrological parameters, biotic associations and long-term socio-economic consequences. However, these arguments do not have a sound scientific basis due to lack of sufficient research data base. So a study was undertaken to find out the impact of these monoculture plantations on soil properties in different pedogenic environments in kerala. Soil profiles were taken from four locations representing different geoclimatic regions of Kerala. The locations were Wynad (Northern forested highland), Kottoor (Southern forested highland), Nileswar (Northern coastal) and Kazhakkoottam (Southern coastal). Altogether thirteen pedons were studied from different locations representing reserve forest, cultivated land, barrenland, Eucaiyptus plantation and Acacia plantation. Pedons were described systematically and subjected to physico-chemical analyses and also for assessing the extent and nature of microflora. Biomass studies and chemical analyses of plant samples have alsobeen undertaken. From the studies, it was revealed that monoculture plantations of Eucalyptus and Acacia have got deleterious impact on soil physical, chemical and biological characteristics. These deleterious effects were more in a forest environment compared to sandy tracts. Increase in gravel content, eluviation of clay, lower silt/clay ratio, increase in bulk density, lower water holding capacity, low moisture content and low water dispersible clay in soils under Eucalyptus in forest areas show that the process of ferrallitisation and soil degradation proceed faster under Eucalyptus. Chemical composition also showed decrease in soil fertility under Eucalyptus. In the sandy tracts, Eucalyptus and Acacia increased the soil organic matter, total nitrogen and available potassium, while almost all other parameters used for the study showed deleterious effects. Active iron ratio (Fe oxalate/ Fe dithionite) was calculated to assess the extent of induration and the results indicated a relative enrichment of crystalline iron oxides in monoculture plantations of Eucalyptus and Acacia which may also lead to induration. A decrease in microbial population was also observed in these plantations except the population of Rhozobium whose number increased in plantations of Acacia which is a leguminous tree. The above results indicated that planting of Eucalyptus and Acacia as monoculture has got very deleterious impact on soil characteristics and fertility . All these throw light on the imminent necessity to have a rethinking about the introduction of monoculture plantations with these exotic species especially in the reserve forest areas.
Influence of Calcium and Magnesium in increasing the efficiency of fertilisers for rice and Calcium and Magnesium status of some typical rice soils of Kerala
(Division of Agricultural Chemistry, Agricultural College and Research Institute, Vellayani, 1963) Thomas Varghese; Subramoney, N
Inter-relationship of potassium with other soil fertility parameters in two major wetland rice soils of Kerala
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1997) Naveen Leno; Thomas Varghese
A study was done at the College of Agriculture, Vellayani during 1994-95 to quantify the different forms of potassium and to investigate the inter-relationships of these forms with other soil fertility parameters. Soil samples were collected from ten locations each, of the two major wet land rice soils of Kerala selected for the study viz., lateritic alluvium of Pattambi (brown hydromorphic) and Onattukara sandy soil (greyish Onattukara) of Kayamkulam. Incubation studies were also carried in both soil types, with and without applied potash, for a period of two months. The study revealed that considerable variation existed in the physico-chemical properties of the two soils. The lateritic alluvium of Pattambi was clayey, high in chloride, organic matter, active iron, CEC, ECEC, exchangeable Ca, Mg and sum of bases and was low with respect to coarse sand and available phosphorus contents and was less acidic as compared to the Onattukara sandy soils of Kayamkulam. The latter was loamy sand in texture with a high content of coarse sand fraction, more acidic, high in phosphorus content and low in clay, chloride, organic matter, active iron, CEC, ECEC, exchangeable Ca, Mg and sum of bases in comparison to the former. Fractionation studies revealed that the Pattambi soils had a higher content of total K, HN03K and fixed K as compared to that of Kayamkularn soils. The high positive correlation of exchangeable K with the available K fraction in both the soil types justifies the existence of a dynamic equilibrium between the two fractions. The .negative correlation of exchangeable and available fractions of K with active iron observed in Pattambi soils was contrary to earlier observations in this regard. Though comparatively high in organic matter, the effect of soil reaction on the available K status was not considerable in Pattambi soils as compared to Kayamkulam soils. This led to the conclusion that management of organic matter in tropical soils is important to maintain the available K status for sustainable farming. The positive inter correlation obtained between lattice K and total K indicated that the major portion of soil potassium existed in the lattice form. The positive and significant association of other forms of potassium was indicative of the existence of a dynamic equilibrium between these forms of K. Potassium fixation was found to be a constraint in Pattambi soils especially with the addition of potassic fertilisers. Hence this should be given due consideration while formulating cost-effective and efficient potassium management strategies since the major chunk of potassic fertilisers are imported in our country.
Pedological and management aspects of hardening and softening of laterites under different land use systems
(Department of Soil Science and Agricultural Chemistry,College of Agriculture, Vellayani, 2000) Byju, G; Thomas Varghese
Pedological investigation on the ecosystem of Vellayani lake
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1994) Sanjeev, V; Thomas Varghese
Potassium status of the major rice soils of Kerala state in relation to their granulometric composition
(Kerala Agricultural University, 1975) Sreedevi, S; Thomas Varghese; Aiyer, R S
A study on the contribution of various size fractions towards !he total K content of the five major acid rice soil groups viz., Kari, Karapadom, Kayal, Kole and low level laterites of Kerala State was conducted. The possible reason for the lack of response of potassic fertilisers in the heavy clay soils like Kari, Kole and Kayal soils is discussed. Higher incidence of coarse fractions and high content of K in such fractions from the laterites suggest the possibility of increased release of reserve K by better soil management practices like application of organic matter.