Effect of Controlled-release and Soluble Fertilizer on Tomato Grown with Seepage Irrigation in Florida Sandy Soils

Florida best management practices include the use of controlled-release fertilizers (CRFs), which are soluble nutrients coated with a resin, polymer, sulfur, or a hybrid of sulfur and polymer. The purpose of this study was to evaluate the effects of three CRF rates in a hybrid CRF/soluble nitrogen fertilizer (SNF) system and two SNF rates using seepage irrigation on tomato (Solanum lycopersicum L.) yields, petiole sap nitrate (NO3-N) content, and postharvest fruit quality. Treatments of 100, 150, and 200 lb/acre CRF plus 50 lb/acre of SNF for total N of 150 (CRF100/SNF50), 200, and 250 lb/acre were compared with IFAS (230 lb/acre) and grower (250 lb/acre) standard of SNF applied pre-plant. Tomatoes were planted on 29 Aug. 2011 using polyethylene mulch. Petiole sap NO3-N contents were above the IFAS sufficiency range for all treatments and sample dates. Soil temperatures ranged from 59.4 to 104.2 degrees F and averaged 79.1 degrees F during the trial, which is higher than the temperature at which manufacturers demonstrate N release. There were no differences in extra-large and total marketable yield at first harvest and total extra-large yield (three harvests combined) among treatments. However, total marketable yield for IFAS, CRF100/SNF50, 150/SNF50, and 200/SNF50 was greater than the grower standard, which ranged from 1,830 to 2,175 25-lb boxes/acre. Grower standards had greater firmness (less fruit deformation) than CRF200/SNF50 13 days after harvest (DAH). Treatments CRF100/SNF50 and 200/SNF50 had the greatest red color among the treatments 13 DAH. A hybrid system containing a significant portion of CRF plus SNF will allow reduced N application with yields similar to IFAS recommended rates.