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ThesisItem Open Access Comparative micromorphologial and physico- chemical study of the upland and midupland laterite soils of Kerala(Department of soil science and agricultural chemistry, College of Agriculture, Vellayani, 1986) Sankarankutty Nair, R; KAU; Aiyer, R SThesisItem Open Access Exchangeable aluminium as an index of liming for the acidic upland soils of Kerala(Department of soil science and agricultural chemistry, College of Agriculture, Vellayani, 1987) Meena, K; KAU; Alice, AbrahamAluminium toxicity is the major factor limiting crop production in the acidic soils and the usual practice of alleviating aluminium toxicity is liming* / The present investigation was carried out to find out the distribution of water s dluhle and exchangeable aluminium in the acidic upland soils of Kerala and to test the suitability of exchangeable aluminium as an index for liming them* It was further programmed to find out the growth, yield and nutrient uptake pattern of two acid sensitive crops namely cowpea and fodder maize in soils under different levels of exchangeable aluminium brought out by the use of different levels of lime* Chemical analysis of eighty soil samples representing the five major upland soil types of Kerala viz* laterlte, alluvial, red loam, sandy and forest a oil have indicated the highest amount of exchangeable aluminium and percentage aluminium saturation in the laterite soils* The soil with 3 high level of exchangeable aluminium and percentage aluminium saturation was selected for conducting a pot culture experiment to test the suitability of using exchangeable aluminium as an index of liming* The exchangeable aluminium content of this soil was maintained at different levels by applying different levels of lime and the performance of these crops in this soil was compared by making biometric observations and by chemically analysing plant and soil samples* From the results of the study it was seen that higher levels of exchangeable aluminium adversely affected the growth, yield and nutrient uptake In cowpea and fodder maize* Maintenance of exchangeable aluminium at 1*26 me/100 g with a corresponding percentage aluminium saturation valua of around 30, by the use of 500 kg lime/ha appeared to be the optimum for maximising the yield of cowpea* But in fodder maize this level of lime was found to be insufficient and complete elimination of aluminium toxicity appeared to be essential for maximising production* Since the critical levels of exchangeable aiuainiua appears to be different for different crop3, it is desirable that lias levels to reduce exchangeable aluminium to such a critical level alono be applied. The results of the present study thus point to the advantage in adopting the exchangeable aluminium level of soil as a better index of liming for various crops grown in the upland acidic soils of Kerala.ThesisItem Open Access Management of acidity by combined application of lime and gypsum in a low activity clay soil of Kerala(Department of soil Science and Agricultural Chemistry, College of agriculture, Vellanikkara, 1992) Jessy, Jacob K; Venugopal, V KThesisItem Open Access Effect of submergence on the soil testing parameters of paddy soils(Department of soil Science and Agricultural Chemistry, College of Agriculture, Vellayani., 1986) Usha, Mathew; Alice, AbrahamThesisItem Open Access Availability indices for stressed nutrients for coconut (Cocos nucifera L) in an ultisol(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2003) Priya, P; KAU; Sureshkumar, PThe present study was conducted with an objective to analyse the soil-plant system, the levels and interactions of nutrient ions in soil, soil solution and plant thereby / finding out the contributing factors to yield. The importance of the term relative intensity lies in the fact that the contribution of mineral elements to growth and yield of plants depend much on the relative amount of one element with respect to the others rather than the absolute content of individual elements. To study the ionic interactions and to unravel the role of Net Ionic Equilibrium based on Ratio Law on soil plant system, a sample of fifty phenotypically identical palms varying in yield from 14.4 to 84.4 nuts palm" year"! grown under an Ultisol were selected. Index leaf samples were collected during pre and post monsoon seasons from 25 palms each from high yielding and low yielding groups. Soil samples were also collected from the basins of these palms during the same seasons at 30 cm (surface) arid 60 cm (subsurface) depths. Soil solutions at saturation point were extracted from the surface samples by centrifugation technique. These leaf, soil and solution samples were analysed / . for different nutrient ions, and the NIE ratios in these three phases were worked out with respect to K and Na. The soil samples were acidic in nature and the variation in rhizosphere pH must have definitely influenced the solubility as well as absorption of different nutrient ions. In the case of available nutrients, the micro nutrients showed significant direct relation with yield both for high and low yielding populations. This might be due to their restricted availability due to aerobic oxidised condition where Fe and Mn might have been precipitated and got into unavailable forms. The BaCh exchangeable ions and the CEC derived from summing up of these exchangeable ions influenced yield directly. Exchangeable K had got a significant dominance in deciding the NIE ratio in soil, solution and in index leaves. Exchangeable K controlled the soil solution concentration of K which in turn controlled the NIE ratio in solution and the ratios in plant. Exchangeable K directly controlled the plant K content and plant K was positively and significantly correlated with the NIE ratios in plant and these ratios were positively and significantly correlated with yield. The negative significant correlation of exchangeable K with plant Mn and Zn revealed the antagonistic effect of exchangeable K in restricting the absorption of Mn and Zn by plants. Among the ionic concentrations in soil solution, Fe was positively and significantly correlated with yield in both the seasons. Soil solution concentrations of Ca and Mg were antagonistically and significantly related with plant Mn content. Potassium content and the NIE ratio in index leaves were found to have a significant direct relation with yield in the pre-monsoon season. Potassium, Ca and Mg were the dominant cations in plant deciding the total cation concentration in index leaves. The NIE ratios between the exchangeable ions, the ions in soil solution and the ions in index leaf samples were mutually, .positively and significantly correlated among themselves. This lead to the conclusion that there exists a constancy in the relative proportion of nutrient ions in the entire soil-plant system which followed Ratio Law. The study lead to the conclusion that the soil test values of the individual ions alone or the plant content of individual ions alone can't give a clear picture of optimum nutrient requirements for the plant. The relative concentration of K in soil through the ~ concentration in soil solution was found to govern the relative concentration in plant which in turn influenced the yield.ThesisItem Open Access Effect of Vermicompost on the yield and quality of tomato (lycopersicon esculentum Mill.)(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1996) Pushpa, S; KAU; Prabhakumari, PAn investigation was carried out at the Instructional Farm, attached to the College of Agriculture, Vellayani to evaluate the Effect of vermicompost on the yield and quality of tomato. The experiment was laid out in Randomised Block Design with ten treatments and three replications. Biometric observations viz. height of the plant, number of leaves and number of floweres were greately influenced by the application of vermicompost compared to farm yard manure. Yield attributes like mean fruit weight and girth of fruits were also found to be significantly influenced by the vermicompost application. Vermicompost application has got a significant influence on the yield of tomato. Plants receiving 25t vermicompost along with full dose of inorganic fertilizers produced maximum yield followed by the plants receiving 25 t farm yard manure along with full dose of inorganic fertilizers. Germination count and viability was maximum when vermicompost was used as the organic source. Maximum germination count and viability was observed when 100t ha-1 vermicompost was used. Vermicompost application has also got a significant influence on fruit qualities. Protein, and carbohydrate content were more in vermicompost treated plants compared to farm yard manure application. Chemical properties of the soil was significantly influenced by the application of vermicompost. pH, organic carbon, available N, P2O5, K2O, Ca and Mg was maximum when 25t vermicompost along with full dose of inorganic ferilizers was used. However availability of micronutrients Mn, Cu, Zn was more in 100t vermicompost applied plots. Application of vermicompost increased the uptake of nutrients by plants. Maximum uptake of all nutrients viz. N, P, K, Ca, Mg, Mn, Cu and Zn was found in plants treated with 25t vermicompost along with full dose of inorganic fertilizers. Correlation studies showed that nutrient uptake was significantly and positively correlated with availability of nutrients. Yield and nutrient uptake of plants were significantly and positively correlated with availability of nutrients and so vermicompost can be effectively used for increasing the fruit yield and quality of fruits in tomato.ThesisItem Open Access 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; KAU; Thomas, VargheseEucalyptus 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.ThesisItem Open Access Behaviour of phosphorus in selected soil types of Kerala(Department of soil science and agricultural chemistry, College of horticulture,Vellanikara, 1993) Vijayan, A P; KAU; Sumam Susan, VargheseIn order to study the distribution of inorganic P-fractions finding suitable chemical extractant for phosphorus, to study Q/1 relationship as a method of estimating available P and for studying adsorption- desorption characteristics of the soil types of Kerala, 100 surface soil samples were collected. These soil types were selected from different parts of the state belonging to five soil types viz., laterite, coastal alluvium, brown hydromorphic, Kuttanad alluvium and black soil. It is observed that all the soil types except black soil were acidic, clay content was comparable in case of black soil, Kuttanad alluvium, brown hydromorphic and lateritic but it was very low in coastal alluvium. Maximum content of sesquioxide and total phosphorus recorded in laterite soils and minimum in coastal alluvium. Dominant inorganic fraction in laterite and black soil was Ca- P while in coastal alluvium, brown hydromorphic, and Kuttanad alluvium dominant fraction was Fe- P. Coastal alluvium recorded maximum content of saloid- P, Al- P and Fe- P content were maximum in Kuttanad alluvium. Maximum content of Ca- P was recorded in black soil. Studies in black soil showed that total P is correlated to free carbonates significantly and positively. The different extractants studied in different soils showed that extractants should be selected according to soil types. Mathew’s triacid proved as a better extractant for available P in laterite and coastal alluvium. In case of Kuttanad alluvium soil Bray No.1 is better. Mathew’s P correlated significantly to uptake in laterite, coastal alluvium and Kuttanad alluvium. Olsen’s P correlated to uptake in laterite and Kuttanad soils. Phosphate potential negatively correlated to uptake in Kuttanad alluvium, coastal alluvium and brown hydromorphic soil. Where as equilibrium phosphate potential negatively correlated to uptake in coastal alluvium alone. DPBC values are not found as a suitable method for the estimation of available P. The P desorption adsorption studies showed that adsorption studies was not correlated to P uptake. While the desorbed P correlated significantly and positively to P uptake in laterite soil alone.ThesisItem Open Access Carbon pools in Lateritic soil amended with coirpith-vermicompost and its effect on Tomato (Solanum lycopersicum L.)(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2019) Aiswarya, R; KAU; Jayasree Sankar, SSoil organic carbon (SOC) is considered as the key indicator of soil quality and agricultural sustainability. Among the different management practices that are being followed, application of chemical fertilizers and manures has been recognized as the most systematic and effective means to either enhance soil organic carbon accumulation or reduce the rate of SOC loss. Hence, for studying the effect of coirpith based vermicompost on dynamics of carbon in a lateritic soil, a field experiment was laid out during October 2018 – February 2019, in RBD with 12 treatments replicated thrice, with tomato, variety Manulakshmi, as the test crop. The plot size was 3 x 3 m and plant spacing was 60 x 60 cm. The treatments consisted of an absolute control (T1), coirpith compost at 10 t ha-1 (T2), coirpith based vermicompost at 10 t ha-1 (T3), Coirpith based vermicompost at 10 t ha-1 + soil test based KAU POP (T4), , FYM at 20 t ha-1 + soil test based KAU POP(T5), T3 + 25 % of soil test based KAU POP (T6), T3 + 50 % of soil test based KAU POP (T7), T3 + 75 % of soil test based KAU POP (T8), FYM at 20 t ha1 + 25 % of soil test based KAU POP (T9), FYM at 20 t ha-1 + 50 % of soil test based KAU POP (T10), FYM at 20 t ha-1 + 75 % of soil test based KAU POP (T11), Adhoc KAU organic POP (T12). Raw coirpith was converted into compost using vermitechnology employing the compost worm Eisenia foetida .The composting process got completed within 64 days time span. Coirpith in the raw stage and after composting was characterized for physical, electro-chemical and chemical properties. Advantages of vermicomposting coirpith included a reduction in the content of lignin (32 to 16.7 %), cellulose (25.2 to 10.2 %), C: N ratio (113:1 to 20.5:1) and EC (0.98 to 0.51 dS m-1) and an increase in pH and total nutrients. Soil analysis after the experiment revealed the significance of treatments on electro-chemical and chemical properties as against the control. Significantly higher available K (281.0 kg ha-1) and Mn (75.33 mg kg-1) was obtained in coirpith based vermicompost at 10 t ha-1 + soil test based KAU POP (T4). In case of N, P, Ca and Fe the effect of the treatments T4, T5 (FYM + soil test based POP) and T8 (Coirpith vermicompost + 75 % soil test based POP) were comparable. The labile C fractions viz. water soluble carbon (WSC), hot water soluble carbon (HWSC), permanganate oxidizable carbon (POXC) and microbial biomass carbon (MBC) were also significantly influenced by the treatments and it followed the order POXC > HWSC > MBC = WSC. Further analysis revealed that the treatments T4, T5, T6 (Coirpith vermicompost + 25 % soil test based POP), T8 and T11 (FYM + 75 % soil test based POP) were comparable in influencing WSC, whereas T4 and T5 were similar in deciding HWSC and T4 and T8 in case of MBC. Significantly higher total C was registered by coirpith vermicompost + 75 per cent soil test based KAU POP. Dehydrogenase activity which is considered as an index of microbial activity in soil was significantly higher (146.3 µg TPF g-1soil 24hr-1) in coirpith based vermicompost at 10 t ha-1 + soil test based KAU POP. Integration of chemical fertilizers at different levels with organics, either coir pith vermicompost or FYM, increased microbial population which followed the order bacteria > fungi > actinomycetes. However, the impact of treatments was more pronounced in enhancing bacterial population due to the shift in pH towards neutral value. On considering biometric observations, it was seen that the plant height (104.7 cm), number of fruits per plant and fruit yield (1.84 kg/plant) were significantly higher for the treatment coirpith based vermicompost at 10 t ha-1 + soil test based KAU POP. The effect of coirpith based vermicompost and FYM along with fertilizers at different levels were comparable in determining fruit quality parameters like total soluble solids, ascorbic acid, lycopene and titrable acidity. Applying coirpith based vermicompost at 10 t ha-1 + soil test based KAU POP registered a higher B: C ratio of 2.43 in contrast to 1.57 recorded in the absolute control.
