YIELD AND RELATIVE COST OF CONTROLLED-RELEASE FERTILIZER ON YOUNG BEARING CITRUS TREES

ROUSE, ROBERT E.

Abstract


Six types of commercially available controlled-release fertilizers (CRFs) (Escote, Meister 9-month, Meister 12- month, Nutricote 360, Prokote Plus, and Sierra) and conventional, water-soluble fertilizer were applied to 'Valencia' orange trees on Swingle rootstock from planting through 6-yr of age. Annual application rates were at full, one-half, and onefourth recommended N rates by UF/IFAS. CRFs were applied once/yr and conventional fertilizer was applied 6, 5, 4 and 3 times in years 1, 2, 3 and 4-6, respectively. Fruit was harvested the 3rd through the 6th yr. Averaged across N rates, Prokote Plus, Nutricote, and Sierra produced 4-yr cumulative fruit yields of 4.9 to 4.8 boxes/tree compared with 4.3 boxes/tree for conventional fertilizer. Prokote Plus and Sierra also produced higher Ibs-solids yield (27.4 Ibs/tree in 4 yr) and gross dollar return ($28.58/tree in 4 yr) than the conventional fertilizer. Prokote Plus out-produced Escote in fruit and Ibs-solids yield, and out-produced Escote and Meister in dollar return. The response of Ibs-solids yield to N rate was described by a quadratic plateau model where the critical N rate varied from 76% of the full N rate for conventional fertilizer (at 26.9 Ibs-solids/ tree) to 100% of the full N rate for Prokote Plus (34.0 Ibs-solids/ tree), Nutricote, and Meister. The cost of fertilizing citrus with CRFs at the full N rate was four times the conventional fertilizer cost, whereas the return was 15% greater. Thus, the current cost of CRF products makes them uneconomical as the primary nutrient source in citrus production.

Keywords


citrus sinensis; nutrition; fruit quality; juice quality

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