Browsing by Author "Dilshara, R.M.P."
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Item Impact of invasion of Cogon grass (Imperata cylindrica) on the physical and chemical properties of soil(Department of Zoology and Environmental Management, University of Kelaniya, Sri Lanka, 2017) Bandara, M.S.P.M.; Dilshara, R.M.P.; Gunarathne, D.K.O.B.; Senevirathne, H.; Udayanthika, S.K.I.; Kumari, C.Cogon grass (Imperata cylindrica) is an invasive species found in many parts of Sri Lanka. This species is among the top ten worst weeds in the world. Cogon grass is found on road sides, mining sites, abandoned plantations and many other areas with disturbed soil forming a dense field like monocultures. The objective of this study was to assess the impact of the invasion of Cogon grass on soil physical and chemical properties. The present study was conducted in a selected site at Nelumdeniya, a village located at Eastern part of Sabaragamuwa Province. Three sites were identified within the study area, of which two sites are invaded by Cogon grass with a high to low level of cover. The remaining site without the weed (undisturbed site) was used to assess the condition of soil before invasion of the weed in above sites. From each site five soil samples were extracted using a soil corer to analyze soil particles density, soil bulk density, porosity, moisture content, organic matter content, conductivity and Nitrogen content (kdjeldahl method) in soil. The moisture content of undisturbed site (0.78) was less than the two sites invaded by the Cogon grass (0.88 and 0.89). The organic matter content (OM) and the Nitrogen content of soil in undisturbed site (OM= 0.163%, N= 0.14%) was higher compared to the other two sites (OM= 0.083% and 0.107%; N= 0.13% and 0.11%). The bulk density and the porosity was higher in affected areas than the undisturbed site. The study reveals that the invasion of Cogon grass affects both the physical and chemical properties of soil.Item Spatial and temporal variations of ground water quality in Kalpitiya peninsula(Faculty of Science, University of Kelaniya, Sri Lanka, 2020) Dilshara, R.M.P.; Handapangoda, H.M.A.K.; Swarnathilake, D.S.G.G.C.; Amarasinghe, L.D.; Herath, H.M.I.K.; Udayanga, N.W.B.A.L.Intensive agricultural practices in Kalpitiya have caused excessive usage of fertilizers. The sandy regosol soil and the over irrigation due to the presence of semi-arid climatic conditions in the area have led to nutrient leaching conditions in Kalpitiya. Since 1990s, the groundwater aquifers in Kalpitiya remain contaminated with higher levels of nitrate due to intensive agricultural practices and the current status of groundwater pollution remains poorly studied. Therefore, this study was conducted to evaluate the current status of groundwater pollution in Kalpitiya, with special emphasis on spatial and seasonal variations. Groundwater samples of 50 wells (potable and agricultural) located in five sentinel sites, namely Nawakkadu, Narakkalli, Thalavila, Kandakuli and Kalpitiya town were collected at monthly intervals from November 2018 to March 2020. In addition, the existing land use practices surrounding the respective wells were also recorded. Selected water quality parameters, namely pH, Electrical Conductivity (EC), Total Dissolved Solids (TDS), salinity, nitrate and phosphate concentrations were analyzed using standard methods. The General Linear Model (GLM) followed by Tukey’s pairwise comparison was used for statistical analysis. Significant spatial variations (p< 0.05) at 95% level of confidence. EC, nitrate, phosphate and TDS levels in groundwater samples of Nawakkadu, Narakkalli, and Kalpitiya town areas remained above the permissible levels for potable water quality given by the Central Environmental Authority (CEA). Therefore, adequate treatment of groundwater is recommended prior to use for drinking purposes.