FERTILIZATION OF YOUNG CITRUS TREES WITH CONTROLLED RELEASE FERTILIZERS

FERGUSON, J. J.

Abstract


Young citrus trees ['Hamlin' orange (Citrus sinensis [L.] Osbeck); 'Marsh' grapefruit (C. paradisi Macf.); 'Ambersweet' orange (C. reticulata Blanco × [C. paradisi Macf. × C. reticulata] × midseason orange C. sinensis (L.) Osb.], all on 'Swingle' citrumelo rootstock [C. paradisi Macf. × Poncirus trifoliata (L.) Raf.] were fertilized for four consecutive years in north central, central and eastern coastal Florida with a granular soluble fertilizer (8% N) at recommended rates (0.47, 0.74, 0.84 and 1.14 lb N/tree/year in years 1, 2, 3, and 4, respectively) and three controlled release fertilizers (17, 19 and 44.5% N) at reduced N rates (0.09, 0.14, 0.19, and 0.19 lb N/tree/year in years 1, 2, 3, and 4, respectively). Tree growth and yields of the different cultivars did not differ significantly with N rate or fertilizer type, although some macro-and micronutrient deficiencies did develop for certain treatments and locations. The total amount of the high analysis (44.5% N) controlled release fertilizer, containing only N and K, applied over 4 years was 5-6% that of the granular soluble fertilizer and 66-72% that of the other controlled release materials, containing N, P, K and micronutrients, suggesting potential reduction in application costs.

Keywords


nutrition; orange; grapefruit

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283