Nutrient release from controlled-release fertilizers in acid substrate in a greenhouse environment: II. Leachate calcium, magnesium, iron, manganese, zinc, copper, and molybdenum concentrations

Abstract

Leachate from containerized substrate containing one of four different controlled-release fertilizers (Osmocote, Nutricote, Polyon, or Multicote) were monitored for concentrations of Ca, Mg, Fe, Mn, Zn, Cu, and Mo during a 47-week period. Environmental and cultural practices simulated an unheated greenhouse production program typically used for low-nutrient-requiring crops such as azalea and camellia. Leachate concentrations of all nutrients were relatively high during the first 10 to 20 weeks of the study, and then gradually decreased during the remaining portion of the experiment. Few differences were observed among fertilizer types. Of the elements monitored, only Fe and Mn leachate concentrations were above critical levels specified in the Clean Water Act by the U.S. EPA.