Growth Response of Azaleas to Fertilizer Tablets, Superphosphate, and Dolomitic Limestone

Abstract

Abstract ‘Mrs. G.G. Gerbing’ azaleas (Rhododendron L.), grown 12 months in a 2 pine bark : 1 Canadian peat : 1 sand (by volume) medium in 3-liter containers and fertilized with Woodace 14N-1P-2K compressed fertilizer tablets, had greater shoot and root dry weights if the medium was not amended with dolomitic limestone, compared to plants grown in the medium amended with dolomitic limestone at 3 kg/m3. Shoot and root dry weights were not different for plants grown with or without a superphosphate (9% P) amendment at 3 kg/m3 in combination with or without the dolomitic limestone amendment. Growing-medium Mn levels were greater (0.5 ppm) without the dolomitic limestone amendment, than with the amendment (0.06 ppm), whereas P levels were similar with or without the dolomitic limestone amendment. On day 60, growing-medium P levels were greatest (10 ppm) for the superphosphate-amended medium without dolomitic limestone and decreased to 0.5 ppm on day 300. Tissue P levels were not different with or without the superphosphate amendment in combination with or without dolomitic limestone.