Browsing by Author "Silva, S.N."

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    Comparison of the effectiveness of liquid and granule fertilizer mixtures on rubber plants raised by young budding technique
    (Rubber Research Institute. Agalawatta, 1997) Dharmakeerthi, R.S.; Yogaratnam, N.Y.; Samarappuli, L.; Silva, S.N.; Yakandawala, A.
    Effectiveness of granule fertilizer mixtures was compared with currently used liquid formulations on plants raised by young budding technique.Granule formulations are agronomicaly effective provided that they are applied in small quantities.Urea based mixtures was found to be comparatively mire detrimental than sulfate of ammonia based mixtures when used at concentrations higher than the recomended levels.Currently recommended fertilizer schedule with liquid formulations was the most effective programme for young budding among the treatments tested.Reduced frequency of application increased the deiback percentage significantly.However,it could be applied at two-week intervals instead of weekly intervals equally effectively,thereby reducing the application cost almost by half.
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    Nutritional status of rubber growing soils in the Moneragala district
    (Rubber Research Institute . Agalawatta, 2005) Dharmakeerthi, R.S.; Silva, S.N.; Yakandawala, A.; Jayasinghe, W.K.
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    Urea hydrolysing potential of the rubber growing soils of Sri Lanka
    (Rubber Research Institute. Agalawatta, 1997) Dharmakeerthi, R.S.; Samarappuli, L.; Silva, S.N.; Yakandawala, A.
    The ability of the rubber growing soils to hydrolyse urea under natural conditions was evaluated by measuring the urease activity using a non buffer method.The temporal variability of urease activity was also investigated during the period February 1994 to February 1995.The urease activity has been ranged from 14.5 to 292.4 ug NH4+-N released/g/h with a mean of 83.84 in all soils.The Matale series soils had a significantly high level of urease activity (120.22) compared to that of the Parambe series(47.88).The level of urease activity in these soils was found to be much higher than the values reported earlier for the same soils.During the first several months after wintering,i.e. from April to September,urease activity was high where as during the period of November,December and January the activity was low in all the series studied.In Parambe and Homagama series soils the urease activity was as low as zero in the months of November and December.The significance of high and low levels of urease activity with regard to urea fertilization in the rubber growing areas was discussed.