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ThesisItem Open Access Improvement of purification system for roof water harvesting(Department of Land and Water Resources and Conservation Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 2015) Swatha, V S; KAU; Sathian, K KThe severity of water scarcity and the need of water conservation, appropriate to the situation, are well understood facts and do not require any further elaboration. Knowing the potential of rooftop rainwater harvesting in Kerala state, the government has introduced legistation making rooftop rainwater harvesting mandatory for all newly constructed residential and commercial buildings. However, the roof water harvesting techniques is crippled with the inefficiency of the commonly employed sand and gravel purification system. The major deficiency of the system lies in the difficulty in cleaning of the filter media. Though studies have been initiated with alternative purification methods, it warrants further modification and improvisation. Keeping this in mind, this M.Tech research work has been taken up to find solutions to the purification issues of rooftop rainwater. The major focus of the work was to develop more efficient micro mesh filter in combination with a first flush system. To evaluate the performance of the filter and first flush, inflow and outflow of the roof water samples were analysed for pH, electrical conductivity, TDS, TSS, metal concentration and microbial parameters. In general, the pH, electrical conductivity and TDS of the roof water samples were within the drinking water standards for the different types of roofs tested. Micromesh purification reduced these quality parameters to further lower levels (10 to 20 percentage). Major TSS load was organic and its concentration was far beyond the permissible limit. Filtration with first flush system could reduce 88 percentage of the organic impurities. Metal and microbial concentrations of the roof water were within the permissible limits, the micromesh filtration could reduce their presence further by about 10 to15 percentage. There is further scope for improving the efficiency of mesh filters by adopting mesh sizes lower than 25 micron for which the discharge of the filter would not be a constraint, as has been revealed by the study.ThesisItem Open Access Comparative evaluation of naturally ventilated polyhouse and rainshelter on the performance of cowpea(Department of Land and Water Resources and Conservation Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 2015) Ajay Gokul, A J; KAU; Abdul Hakkim, V MA study was conducted in the Instructional Farm of KCAET, Tavanur, Kerala, during the period from August to December 2014 to compare the performance of cowpea grown under polyhouse and rainshelter in relation to open field cultivation. Cowpea variety Vellayani Jyothika, a trailing type legume released by KAU, was used for the study. Fertilizers were applied through drip irrigation system using venturi assembly. The variation of weather parameters such as maximum and minimum temperature, relative humidity, soil temperature and rainfall during the crop growth period was studied. Mean monthly values of temperature, relative humidity and soil temperature inside the polyhouse was higher than that in rainshelter and open field throughout the growth period. The maximum rainfall (360.7 mm) was recorded in the month of October and minimum rainfall (6.3 mm) was recorded in the month of December. Crop growth parameters such as plant height, internodal length, number of branches and time taken for flower initiation were noted during various crop growth stages for all the treatments. During all growth stages, the plant height and internodal length were significantly higher inside the polyhouse followed by rainshelter and open field. Among the different treatments, early flower initiation (39 days) was noted in the polyhouse. Yield parameters such as number of pods per plant, average length of pods and total yield per plant for each treatment were noted during various crop growth stages. The number of pods per plant was significantly higher in open field. Average length of pods inside polyhouse and inside rainshelter was higher than that in the open field. There was no significant difference in total yield of cowpea harvested from the observation plants under the three treatments. The maximum Benefit Cost ratio of 1.73 was obtained in the open field cultivation. Benefit Cost ratio of polyhouse and rainshelter were 1.06 and 1.34 respectively. Incidence of pests and diseases were also comparatively low inside the rainshelter and higher incidence of pests and diseases were noticed in the open field. From the results of the study it was evident that growing cowpea (Vellayani Jyothika) inside the rainshelter is more profitable than growing it inside naturally ventilated polyhouse.ThesisItem Open Access Design, development and evaluation of an automated drip irrigation system(Department of Land and Water Resources and Conservation Engineering, Kelappaji College of Agricultural Engineering and technology, Tavanur, 2014) Navneet, Sharma; KAU; Abdul Hakkim, V MThe present study was conducted to design, develop and evaluate an automated drip irrigation system working on the basis of soil moisture deficit and to establish the relationship between soil moisture content, electrical conductivity. The study involved fabrication of a soil moisture deficit based automation system and testing of the system under laboratory and field conditions. The system was tested and calibrated for automatic irrigation scheduling. As the soil started drying up, water content decreased and the conductivity reading in the data logger decreased. When the sensor readings reach the preset threshold level, the system gets automatically switched on. The irrigation setup was operated until the moisture reached the preset level of field capacity. Conversely, an increase the soil water content increased the conductivity. In this way, automation system continuously recorded fluctuations in soil moisture content under varying field conditions. Laboratory tests were conducted to evaluate the performance of the drip automation system in salt solution, sandy loam and laterite soils to develop the calibration curves. It was observed that there existed a significant correlation between the soil moisture content and electrical conductivity of sensors. Soil moisture sensors were evaluated with respect to the moisture content of sandy loam and laterite soils. In sandy loam soil, the values of maximum and minimum sensor output values were 17.5 to 3.3 mS/m and for laterite soil it was 15.1 to 2.4 mS/m. In the field evaluation using amaranths crop, the moisture distribution was more or less uniform near the soil surface soon after irrigation. The developed electrical conductivity based soil moisture sensors performed well in the laboratory study using sandy loam and laterite soils, but during field evaluation in sandy loam soil its performance was not satisfactory. In case of capacitor type soil moisture sensor, the performance was satisfactory in both conditions. Capacitor type soil moisture sensor performed well in sandy loam soil in the field evaluation. From the results of this study it can be concluded that capacitor type soil moisture sensor can perform better than electrical conductivity based soil moisture sensor for field use. The drip automation system developed was simple, precise, sensitive, light weight, cost effective in construction and fast responding. The speed of measurement, cheapness and portability are the key advantages and the system is easily adaptable for use with automatic logging equipment. There is scope for further studies on optimization of the electrode geometry and evaluation of electrical conductivity based soil moisture sensors with different fertilizer and chemical application.