Skip to main content
ARS Home » Research » Publications at this Location » Publication #188396
Title: NUTRIENT RELEASE FROM CONTROLLED-RELEASE FERTILIZERS IN ACID SUBSTRATE IN A GREENHOUSE ENVIRONMENT: I. LEACHATE ELECTRICAL CONDUCTIVITY, PH, AND NITROGEN, PHOSPHORUS, AND POTASSIUM CONCENTRATIONS

Author
item MERHAUT, DONALD - UC-RIVERSIDE
item BLYTHE, EUGENE - UC-RIVERSIDE
item NEWMAN, JULIE - UC-RIVERSIDE
item Albano, Joseph

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/6/2006
Publication Date: 6/1/2006
Citation: Merhaut, D.J., Blythe, E.K., Newman, J.P., Albano, J.P. 2006. Nutrient release from controlled-release fertilizers in acid substrate in a greenhouse environment: i. leachate electrical conductivity, ph, and nitrogen, phosphorus, and potassium concentrations. HortScience.41(3):780-787.

Interpretive Summary: Controlled release fertilizers (CRF) are designed to provide a steady supply of nutrients to plants over a specificed time. Nutrient release for such fertilizers is typically dependent on temperature with an increasing temperature yielding an increase in nutrient release. In the project we studied the release characteristics for ammonium, nitrate, total phosphorous, and potassium over a 47-week period for four commonly used CRF (Osmocote, Nutricote, Polyon, and Multicote). We found that the release rates for the selected 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. Differences were observed among the fertilizers and nitrate and total-phosphorous runoff from the container, using the manufacturers apllication rate, often exceeded permissible levels as cited in the federal Clean Water Act.

Technical Abstract: Release characteristics of four types of controlled-release fertilizers (Osmocote, Nutricote, Polyon, and Multicote) were studied during a 47-week simulated plant production cycle. 2.4 L containers containing a low-fertility, acid-based substrate were placed in an unheated greenhouse and subjected to environmental conditions often used for production of azaleas and camellias. Leachate from containers was collected weekly and monitored for pH, electrical conductivity, and concentrations of NH4+-N, NO3 -N, total P and total K. 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. Differences were observed among fertilizer types. Concentrations of NO3 and P3 were often above permissible levels as cited in the federal Clean Water Act.