1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Organic nano NPK fomulations for enhanching soil health and productivity(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2019) Nibin, P M; Ushakumari, KItem Herbicide mixtures for weed management in direct seeded puddled rice (Oryza sativa L.)(Department of Agronomy,College of Agriculture, Vellayani, 2016) Sheeja K Raj; Elizabeth K SyriacItem Enzyme characterization of the acid sulphate soils of Kuttanad(Department of Soil Science and Agricultural Chemistry, college of Agriculture, Vellayani, 2016) Arya Nath, V; Aparna, BRegarding the enzyme status of the acid sulphate soils, the activity of urease was the highest in Thakazhi (L4-75.78 ppm of urea hydrolyzed g-1 soil h-1) in the surface layer. Acid and alkaline phosphatase activities were found to be the highest in Purakkad (L3-57.58 μg pnp released g-1 soil h-1) and Thakazhi series (L4-46.41 μg pnp released g-1 soil h-1) respectively in the surface layers. The highest activity of dehydrogenase was noticed in Thuravur series (L6-115.74 μg of TPF released g-1 soil 24 h-1) in the surface and Kallara series in the subsurface layers (L2-55.39 μg of TPF released g-1 soil 24 h-1). Karappadam and Kayal recorded the values of 145.73 and 114.80 μg of TPF released g-1 soil 24 h-1 for dehydrogenase activity respectively at surface layers. With regard to the microbial population, Thottappalli (L5) recorded the highest total bacterial count and fungal population in both surface and subsurface layers. Thiobacillus spp. recorded the highest population of 9.08 log cfu g-1 of soil at Kallara series (L2) while P solubilizers recorded the highest count at Ambalapuzha series (L1). Thuravur series recorded the highest actinomycetes population in subsurface soils. Micahelis – Menten constant, Km and the maximum velocity Vmax for different enzymes were determined and it was observed that for dehydrogenase Vmax value was found to be the highest in 6th week and for phosphatase only after 12th week of incubation. Thematic maps were prepared based on themes like microflora and enzyme status using GIS (ARC VIEW). Hence the study conclude that, with respect to biological fertility status of the study area, Purakkad recorded the highest enzyme activity number (23.69) at 0-15 cm, while Kallara series recorded the highest enzyme activity number in the subsurface layer and are observed to be biologically sustainable.Item Assessment of soil health and status of heavy metals in the certified organic farms of Kerala(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2019) Greeshma, P R; Usha MathewThe study entitled “Assessment of soil health and status of heavy metals in the certified organic farms of Kerala” was conducted from 2017 to 2019. The objective of the study was to assess and compare the soil health parameters and heavy metal status of the inputs and produce of certified organic farms and conventional farms of Kerala. Samples of soil, inputs and plant produce were collected from different locations of Kerala representing Northern, Hill, Central and Southern zones. The organic farms selected for study were under NPOP certification for more than 10 years. The rate of application of manures in organic and conventional farms were 30 t ha-1 and 2 t ha-1 respectively. The first part of investigation was conducted to comparatively evaluate the effect of organic and conventional farming on soil health, for which composite soil samples from 2 depths (0-15 cm and 15-30 cm) were collected from 10 numbers each of certified organic farms and conventional farms. The collected soil samples were analysed for physical, chemical and biological properties from which soil quality index was calculated for each sample and an in situ enumeration of earthworms and arthropods was conducted by excavating 1 m3 soil in all the farms from where soil samples were collected. Among the physical and chemical properties analysed, available N, K, Ca, Zn and Cu at 0-15 cm depth were significantly higher in soils from organic farms than conventional farms. Bulk density was found to be lower in soils of organic farms which is a good soil quality attribute. pH was significantly lower in soils of organic farms at 0-15 cm depth. Total as well as available content of heavy metals were (Ni, Cd and Pb) were not significantly different among the organic and conventional soil samples. Unlike physical and chemical properties, all biological properties were significantly higher in soils of organic farms than conventional farms. Bacterial, fungal, actinomycetes count, earthworms, soil arthropods and dehydrogenase activity were found to be significantly higher in soils of organic farms than in conventional farms at both depths and respiratory activity was found to be significantly higher in organic farms at 0-15 cm depth. Soil quality index was calculated from various physical, chemical and biological soil properties and the highest index (61.1 per cent) was obtained in the surface soils of hill zone under both management. However the highest soil quality index was observed only in soils of organic farms in Northern and Southern zones. The second part of investigation was input analysis in which inputs used in organic and conventional farms, available at the time of sampling were analysed for Zn, Cu, Cd, Ni and Pb. The results revealed that except for the content of Cu in manures and fertilizers, other heavy metals were not observed to be significantly different in manures and fertilizers. The third part of investigation was plant study, in which edible parts of 10 crops were collected from both organic and conventional farms and analysed for Zn, Cu, Cd, Ni and Pb. Except for Zn, other heavy metals were found to be very much within the limit of food safety standards. Zn was found to be high in amaranthus from both organic (96 mg kg-1) and conventional (105.6 mg kg-1) farms. Content of Zn in yard long bean, salad cucumber and curry leaf from organic farms (60-64 mg kg-1) and was found to be just exceeding the safe limit (60 mg kg-1). Zn in plants was found to be significantly affected by management practices also. A significant positive correlation have been observed between the content of Zn in plants and available Zn in soil in both conventional and organically managed soils. From the study it may be concluded that soil quality was found to be generally high in hill zone soils compared to other zones irrespective of the management practice and in all other regions, organic farming was found to be increasing the soil quality. Heavy metals in inputs and plant produce analysed were very much within safety standards. Zn content of amaranthus in organic and conventional farms exceeded the food safety limit. A significantly higher biological properties of soils in organic farms clearly manifests the long term sustainability of organic farming in Kerala’s climatic condition.Item Root phenomics and soil biological acitivity in response to thermochemical organic fertilizer application(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2019) Ramesha, G K; Naveen LenoItem Characterization and evaluation of on-farm liquid organic manures on soil health and crop nutrition(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2017) Sreya U Parvathi; Ushakumari, KItem Effect of agrochemicals on biological activity in lateritic soil(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2018) Nisha Paul; Durga Devi, K MIn modern agriculture, agrochemicals are frequently used to boost crop production. The use of pesticides is indispensable in various crops and cropping systems, particularly under tropical climatic condition. However erratic application of these chemicals may affect soil health, which in turn change the population and composition of soil microflora and soil fertility. The land use type also play a significant role in controlling the microbial community. Hence, the present study was undertaken at College of Horticulture, Vellanikkara during 2017-2018 so as to determine the impact of three agrochemicals viz. oxyfluorfen, copper oxychloride and chlorpyriphos on the population of soil microflora and dehydrogenase enzyme activity in lateritic soil collected from two land use types. Representative soil samples were collected from two land use types viz., land under cultivated grass, Agronomy farm, College of Horticulture, Vellanikkara (LUT 1) and cocoa plantation, Cocoa Research Center, KAU, Vellanikkara (LUT 2) during August, 2017. The soil samples were analyzed to assess physical, chemical and biological characteristics before starting experiment and the data revealed that soil collected from LUT 2 was more conducive for microbial growth and dehydrogenase activity. Pot culture experiment with cowpea (variety: Bhagyalakshmi) was conducted during March to June, 2018 with fourteen treatments (3 agrochemicals at 2 different doses under each land use types + 2 controls, one each for two land use types) and three replications. Agrochemicals viz., oxyflourfen (OXY) at 0.15 and 0.30 kg ha-1 (herbicide), copper oxychloride (COC) at 0.75 and 1.50 kg ha-1 (fungicide) and chlorpyriphos (CHL) at 0.30 and 0.60 kg ha-1 (insecticide) were selected for the study. Soil samples were analyzed at four intervals viz., 7, 30, 60 and 90 days after agrochemical spraying (DAS) to evaluate the effect of agrochemicals on chemical and biological characteristics of soil. The chemical characteristics of soil viz., pH, electrical conductivity, organic carbon, available N, P, K, Ca, Mg, S and micro nutrients like Fe, Mn, Cu, and Zn followed a decreasing trend towards the harvest in all the treatments under both the land use types. The effect of agrochemical application on chemical characteristics and nutrient availability of the soil was at lower magnitude compared to their influence on biological activity of the soil. The biological characteristics of soil viz. dehydrogenase activity and microbial population (fungi, bacteria and actinomycetes) were higher in soil samples collected from LUT 2 (cocoa plantation) at all the sampling intervals. Soil samples from both the land use types registered reduction in biological activity due to agrochemical application, which was higher at 7 DAS than the other sampling intervals. The extent of reduction in biological activity after application of agrochemicals was comparatively higher in LUT 1 (land under cultivated grass). Higher doses of the pesticides showed greater decline compared to their lower doses. Biological activity increased from 7 to 60 DAS and the extent of reduction with respect to control also became lower. At 90 DAS, a declining trend in the dehydrogenase activity and microbial population (except fungi) was noticed. The adverse effect of agrochemicals on dehydrogenase activity and bacterial population at 7 DAS followed the order: CHL > COC > OXY and OXY > CHL > COC respectively. However at 90 DAS, oxyflourfen exerted minimum adverse effect on soil bacteria. The study revealed that dehydrogenase activity is highly correlated with the population of soil microflora, especially soil bacteria. The adverse effect of agrochemicals on fungal population can be ranked as: COC > OXY > CHL at both 7 and 90 DAS. The percentage inhibition of actinomycetes population at 7 as well as 90 days after agrochemical application was in the order: OXY > COC > CHL. Cowpea yield was not affected by the agrochemical application and land use types. However higher doses of all the agrochemicals under study reduced the number of root nodules in cowpea.Item Effect of phosphorus solubilisers on the availability of native P in phosphorus rich soil(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2018) Sreelakshmi, M M; Aparna, BItem Productivity and soil health of rice based cropping systems under organic management(Department of Agronomy, College of Horticulture, Vellanikkara, 2018) Rajanand Hiremath; Usha, K EItem Acidity amelioration and nutrient management practices for mitigating yield constraints of rice in Vaikom Kari(Department of Agronomy, College of Agriculture, Vellayani, 2017) Devi, V S; Kumari Swadija, O