NITRATE, PHOSPHATE, AND POTASSIUM LEACHING FROM CONTAINER-GROWN PLANTS FERTILIZED BY SEVERAL METHODS

Spathiphyllum Schott,'Mauna Loa Supreme' and areca palm (Chrysalidocar pus lutescens H, Wendl,) were grown for 6 months in 3,5-liter containe rs 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 co llected and analyzed weekly for NO3-N, PO4-P, and K, Amounts of all th ree nutrients leached per week varied considerably in response to fert ilizer reapplications or high rainfall. Nitrate leaching generally dec reased over time, PO4-P leaching increased, and K remained relatively constant, Shoot dry weights of spathiphyllum were equivalent for all f ertilization methods, but areca palm shoot dry weights were highest wi th liquid fertilization and lowest with the soluble granular fertilize r, Nutrient leaching for all three ions was highest for the soluble gr anules and lowest for the two controlled-release formulations.