| dc.description.abstract | Intensive agriculture practices together with increased fertilizer use have a greater
impact on groundwater quality in Kalpitiya. Water demand in Kalpitiya is 70%,
fulfilled by groundwater extractions. The permeable nature of sandy Regosols
causes leaching of nutrients and contamination of shallow groundwater. The aim of
this study was to evaluate the effects of different fertilizer practices on growth, yield
and nutrient leaching in leafy red onion grown in Kalpitiya. The red onion is the
major crop grown in large scale. The treatments tested were T1-Farmer Used Rate
of fertilizer and T2-Department of Agriculture recommendation. The experiment
was arranged in Completely Randomised Block Design with three replicates in six
plots (7.2m2). The red variety of Jaffna Local was established in a research field
where lysimeters were previously installed. The leachate was collected weekly from
lysimeters and analysed for leached nitrogen. Growth of plants and yield were
recorded. A significant difference in leached nitrogen was observed between
treatments. Furthermore, it was observed that there was a statistically significant
difference between the final yield of T1 and T2 treatments. The total nitrogen
leaching percentage of T2(67.88%) was lower than T1(78.86%), even though the
crop yield of T2 (5069.25kg/ac) was lower than T1(7556.95kg/ac). The average
concentration of nitrate in the leachate of T1 was 73mg/l, while that of T2 was
72mg/l. The safe limit of nitrate in groundwater is 50mg/l. Recommended amounts
of fertilizer should be applied in balanced proportion and at appropriate times with
soil amendments, which may help to absorb nutrients efficiently. Therefore, the
study concludes that both practices showed leached nitrate concentrations above
safe limits recommended by WHO, which urges the need for change in nitrogen
fertilizer management for red onion on sandy regosols. | en_US |
