(48) Substrate Media and Fertilizer Source Affect Nitrogen and Phosphorus Levels in Leachate from Container-grown Shasta Daisy

Abstract

Plugs of Leucanthemum × superbum `Becky' (Chrysanthemum `Becky', shasta daisy) were grown in #2 containers using pine bark–peat–sand or vermiculite–peat–sand (40:40:20 by volume). Containers were top dressed with either Osmocote Plus 15N–3.9P–9.9K (15–9–12) or Nutricote Plus (18N–2.6P–6.6K (18–6–8) at five rates (0, 0.5×, 1.0×, 1.5×, and 2.0×) to supply 3.9 g N per container at the recommended level (1.0×). Plants were irrigated twice a week using a cyclic irrigation regime consisting of two irrigation applications. Leachates from these containers were collected and evaluated for nitrate and orthophosphate concentrations. Irrespective of the substrate media, Osmocote Plus exhibited a higher rate of nitrogen release at the beginning of the season than Nutricote Plus. Nitrate nitrogen concentration was at least 2.5 times higher in leachates collected from media amended with Osmocote Plus than those with Nutricote Plus. Higher levels of nitrate were found in leachates collected from vermiculite-based media when compared to those from bark-based ones. Phosphate levels in leachates increased as rate of fertilizer increased and were higher in vermiculite-based media than those collected from bark-based media. Plants fertilized with Osmocote Plus were 1.7-fold greater in dry weight than plants fertilized with Nutricote Plus and were 1.2 times greater in vermiculite-based media than those in bark-based media.