Nitrate, Phosphate, and Potassium Leaching from Container-grown Plants Fertilized by Several Methods

Abstract

Spathiphyllum Schott. `Mauna Loa Supreme' and areca palm (Chrysalidocarpus lutescens H. Wendl.) were grown for 6 months in 3.5-liter containers using a pine bark–sedge peat–sand container medium or a native sand soil. Plants were fertilized with equivalent amounts of a 21N–3P–12K fertilizer applied weekly as a liquid, monthly as a soluble granular, bimonthly as a lightly coated controlled-release, or every 6 months as a heavily coated controlled-release fertilizer. All leachates were collected and analyzed weekly for NO3-N, PO4-P, and K. Amounts of all three nutrients leached per week varied considerably in response to fertilizer reapplications or high rainfall. Nitrate leaching generally decreased over time, PO4-P leaching increased, and K remained relatively constant. Shoot dry weights of spathiphyllum were equivalent for all fertilization methods, but areca palm shoot dry weights were highest with liquid fertilization and lowest with the soluble granular fertilizer. Nutrient leaching for all three ions was highest for the soluble granules and lowest for the two controlled-release formulations.