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1985 - 198911990 - 19961
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Subject: Soil Science and Agriculture Chemistry × Author: Betty, Bastin × Author: KAU × Start date: 1980 ×
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    ThesisItemOpen Access
    Physico-chemical characterisation of red soils in different regions of Kerala
    (Department of soil science and agricultural chemistry, College of Horticulture, Vellanikkara, 1985) Betty, Bastin; KAU; Venugopal, V K
    In the present study an attempt has been made to evaluate the morphological, physical and chemical characteristics of red soils occurring in different regions of Kerala. Six soil series representing red soils identified by the soil survey unit of the department of Agriculture, Kerala state were selected for the investigation. The series identified were Vellayani, Cherniyoor, Bharanikkavu, Beypore, Chirakkal and Kunhimangalam located in Trivandrum, Quilon, Calicut and Cannanore districts. Profile pits were dug at these different locations and examined for their morphological features. Soil samples representing the different horizons were collected for laboratory studies. The physico-chemical characteristics of the soils and chemical composition of clays of the profile samples were investigated with a view to study the interrelationship between the various properties and to relate these characteristics to the genesis of these soils. Surface samples collected from different locations under each series were also analysed for available nutrients. The morphological features of the soil profiles revealed prominent red hues with increase in redness with depth. All the soil profiles were well drained, with ill defined horizons, exhibited good structural development and were devoid of coarse fragments. The soils were all sandy in nature, with the fine sand fraction predominating. Clay illuviation was observed in all the profiles. In respect of available water content appreciable variation was not observed between soil series. The highest available water content was recorded in Kunhimangalam series while beypore series had the lowest. All soils were acidic with very low electrical conductivity. The organic carbon, nitrogen and C/N ratios were low and showed little variation between soil series. Silica recorded very high values for all the soils while total Fe2 O3 and AI2 O3 did not reveal much variations between soil series. The total reserves of CaO, MgO, K2 O and P2 O5 were very low and is mainly a reflection of minerology of sand fraction which was dominated by quartz. In respect of total micronutrients iron and manganese recorded high values while Zinc and copper were low and did not reveal much variations between the different soils. Iron, Zinc and copper showed positive relationship with finer fraction while in the case of manganese, the relationship holds good in the case of fine sand fraction only. The e. c. e. c. values obtained were very low and less than the c. e. c. values determined by neutral N NH4 OAc method. Effective c. e. c. showed positive significant relationship with organic matter. The content of exchangeable bases were in the order Ca Mg Na K. Exchangeable hydrogen was more than exchangeable aluminium. Cherniyoor series recorded the highest percentage base saturation while the lowest value was obtained for Kunhimangalam series. The dithionite extractable iron was the predominant iron fraction in all the soils and based on the ‘degree of freeness of iron’ Kunhimangalam series was the oldest in respect of age followed by Chirakkal, Cherniyoor, Vellayani, Beypore and Bharanikkavu. The Ammonium oxalate extractable iron and iron oxide ratio, recorded very low values for all the soil series. The available nutrients of the surface samples showed high levels of phosphorus in all the soils. Nitrogen was low to medium in Vellayani, Cherniyoor and Beypore while it was medium in Bharanikkavu, Chirakkal and Kunhimangalam series. In the case of available potassium loe to medium levels were observed in Chirakkal, Bharanikkavu, Beypore and Cherniyoor series while Kunhimangalam and Vellayani series showed low levels of available potassium. The phosphorus fixing capacity for all the series was high. The DTPA extractable iron and manganese were more than adequate in the surface horizons of all the series. Zinc was deficient to adequate in Vellayani, Bharanikkavu and Kunhimangalam series and marginal to adequate in Cherniyoor, Beypore and Chirakkal series. Copper was deficient to adequate to Vellayani, Cherniyoor and Kunhimangalam series, while adequate levels were observed in Bharanikkavu, Beypore and Chirakkal series. Silica formed the predominant element of the clay fraction. The Si O2/AI2 O3, Si O2/Fe2 O3 and Si O2/R2 O3 ratios recorded for all the soils were higher than the values reported for typical laterite soils.
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    ThesisItemOpen Access
    Fate of carbofuran applied to the soil basin of black pepper
    (Department of Soil science and Agricultural chemistry, College of Horticulture, Vellanikkara, 1996) Betty, Bastin; KAU; Wahid, P A
    An investigation on the fate of carbofuran applied to the soil basin of black pepper (Piper nigrum L.) was conducted during 1992-1995 at the College of Horticulture, Vellanikkara. Laterite soils collected from the predominant pepper growing tracts of Kannur and Wayanad of Kerala state were used for the study. A field study was also conducted at the KADP farm attached to the College of Horticulture, Vellanikkara. The sorption of carbofuran in laterite soils and its persistence, influence of organic matter on the bio-availability of carbofuran, mobility of the insecticide in soil under field conditions and the effect of carbofuran on the growth of black pepper were assessed. The main findings of the study are given below. The sorption of insecticide in soil was found to be explained by Freundlich adsorption equation. The rates of sorption of carbofuran was not influenced by the organic matter contents . . An initial lag period was observed prior to carbofuran degradation in soil under laboratory conditions. Only one metabolite (3-hydroxycarbofuran) was detected as the product of degradation. The total content of 14C derived radioactivity was high in plants grown in soils with lowest organic matter content and vice versa. Hence, bioavailability of the insecticide is less in soils with high organic matter contents. So a discriminatory application of carbofuran is required depending on organic matter content of the soil. Thus for effective control of the pest in a soil with high organic matter content more quantity or carbofuran has to he applied than a soil with low content of organic matter. The residues of 14C-carbofuran absorbed plants left after HCl extraction, retained significant amounts of radioactivity which could be recovered following combustion. This indicated that determination of extraction efficiency by spiking or fortification of the samples with known quantities of insecticides would lead to overestimation of the recovery. The main metabolite of the carbofuran in the leaves was 3-hydroxy- carbofuran. Autoradiography of the bush pepper plants which was allowed to absorb 14C-carbofuran for 6 h showed that carbofuran was absorbed and translocated to the leaves and berry. Both carbofuran and hydroxycarbofuran were leached to the lower layers of soil (0-60 cm) during SW and NE monsoons. The content of hydroxycarbofuran was less than carbofuran in soils. In the foliage and berries carbofuran and the metabolite, 3-hydroxy- carbofuran accumulated. The content of hydroxycarbofuran was greater than that of carbofuran. As the harvesting time was delayed the content of residues also decreased. The early harvesting and use of immature berries may lead to more concentration of pesticide in the produce. This will lead to chances of more residue build-up in the human system.