Browsing by Author "Byju, G"

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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 land uses on soil acidity parameters in a typical laterite terrain from Kerala
(Kerala Agricultural University, Vellanikara, 2001) Byju, G; Thomas, Varghese
Cassava (Manihot esculenta Crantz) and rubber (Hevea brasilienis Muell. Arg.) form the major land uses along the midland region of Kerala where laterite soils predominate. .Thisstudy was conducted to find out the comparative impact of cassava and rubber on soil acidity parameters at Angadippuram in Kerala state, which is considered as the 'type locality' of laterite soils. Pedons were dug to a depth of 2 m from three selected land uses viz., cassava, rubber and uncultivated barren and genetic horizon samples were collected to study various soil acidity parameters. The study showed that all the pedons under study have a negative ApH value indicating a net negative surface charge throughout the profiles. Highest negative ApH value was noted, among surface horizons, in soils under rubber. Amorphous alumino-silicates could be observed in the surface layers of all three pedons as indicated by high pH (NaF) values. The exchange sites and soil solutions were dominated by exchangeable aluminium and the values were very high in textural-B horizons and hard laterite layers. The surface horizon of soils under cassava recorded significantly lower exchangeable Al compared to other two land uses. The base saturation values (sum of cations) for surface horizons were 25.60, 21.57 and 19.14 per cent respectively for pedons under cassava, rubber and uncultivated barren.
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
Soil acidity parameters of laterite soils under rubber
(Kerala Agricultural University, Vellanikara, 2001) Byju, G; Thomas, Varghese
A study was conducted to understand the soil acidity parameters of three selected laterite soils under rubber in Kerala. Pedons were dug to a depth of 2 m at three selected locations viz. Thiruvananthapuram, Angadippuram and Kannur and genetic horizon samples were collected to study various soil acidity parameters. The study showed that all the pedons under investigation have a negative ApH value indicating a net negative surface charge throughout the profiles. Amorphous alumino-silicates could be observed in the surface layers of all three pedons as indicated by high pH (NaF) values. The exchange sites and soil solutions were dominated by exchangeable aluminium and the values were very high in textural-B horizons and hard laterite layers. The base saturation values (sum of cations) for surface horizons were 25.33, 21.90 and 21.57 per cent in pedons at Thiruvananthapuram, Kannur and Angadippuram respectively