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Controlled-release fertilizer (CRF) use is a best management practice that may reduce nitrogen (N) loss to the environment. Several factors affect CRF nutrient release; therefore, including CRF in a fertilization program may have challenges. Thus, the study objective was to evaluate the effects of CRF N rate, source, release duration, and placement on seepage-irrigated marketable tomato (Solanum lycopersicum L.) yield, leaf tissue N (LTN) concentration, post-season soil N content, and postharvest fruit firmness and color. There were two soluble fertilizer (SF) controls [University of Florida/Institute of Food and Agriculture Sciences (UF/IFAS) (224 kg·ha⁻¹) and grower standard (280 kg·ha⁻¹)] and six and seven CRF treatments (alone or in combination with SF) in Fall 2011 and 2012, respectively. Cumulative rainfall totaled 31.4 and 37.4 cm during the 2011 and 2012 seasons with average air temperatures of 22.4 and 22.1 °C, respectively. Soil temperatures ranged from 14.2 to 40.6 °C in 2011 and 11.1 to 36.6 °C in 2012 with a strong correlation (r = 0.95) to air temperature. Controlled-release urea resulted in 7.5% to 17.9% plant mortality in 2011 and reduced yields in 2012 compared with CRF N–phosphorus–potassium (NPK) at a similar N rate. LTN concentrations were above or within the sufficiency range for all treatments. In 2011, using CRF-urea at 190 kg·ha⁻¹ N produced similar marketable tomato yield in all fruit categories except season total large tomatoes, which produced significantly fewer marketable tomatoes with 13.5 Mg·ha⁻¹ compared with UF/IFAS and grower standard with 17.9 and 14.2 Mg·ha⁻¹, respectively. In 2012, CRF-NPK (168 kg·ha⁻¹ N) significantly reduced first and second harvest combined large and season total large and total marketable yields compared with the UF/IFAS rate and grower standard treatments. Marketable yield was not significantly affected by CRF (urea or NPK) release duration, but CRF-NPK 180-day release duration significantly increased residual soil N in 2012 compared with CRF-NPK 120-day release with 74.2 and 34.3 kg·ha⁻¹ N, respectively. Rototilling CRF-urea into the bed, which was only evaluated in 2011, significantly increased total season yields compared with CRF-urea broadcast in row before bedding (BIR) with 43.0 and 46.5 Mg·ha⁻¹, respectively. There were no significant yield differences when 50% or 75% of the total N was CRF placed in the hybrid fertilizer system, which is a system with CRF placed BIR with the remaining N as SF-N banded on the bed shoulders. No significant differences among treatments were found for total residual soil N in 2011; however, higher soil N remained in CRF (NPK and urea) treatments compared with SF treatments in 2012, except for Treatment 9. No significant differences were found among treatments for fruit firmness or color in 2011 or 2012. CRF-NPK at 190 to 224 kg·ha⁻¹ N with a 120-day release may be recommended as a result of similar or greater first harvest and total season marketable yields compared with IFAS-recommended rates and low residual soil N. Further research must be conducted to explore CRF placement and percentage urea composition, although use of the hybrid system or rototilling may be recommended.

Several experiments were conducted in commercial tomato (Solanum lycopersicum) plantings during the 2004–05 and 2005–06 seasons in Immokalee, FL, to understand types of plant damage and potential yield reductions caused by hurricanes. Expt. 1 involved ‘Florida 91’ tomato seedlings damaged during 2004 by hurricane Frances, 15 days after transplanting (DAT). Individual plants were rated and categorized as best, good, or fair, 34 DAT according to plant size and vigor/severity of injury. Ten plants from each category were removed with roots intact, and dry weights were recorded. During 2005, 23 DAT or 8 days after hurricane Wilma, Expt. 2 was conducted to compare rescued and replanted ‘Soraya’ tomato seedlings. Rescued seedlings were left in place after the hurricane and others were removed and replaced with new transplants of the same variety. Expt. 3 (‘Florida 47’) and 4 (‘BHN 586’) involved the contrast of two yield seasons without a hurricane (2004–05) and with hurricane Wilma (2005–06) to estimate the effect of the hurricane damage on tomato 65 and 45 DAT. Fruit was counted, graded by size, and weighed for each experiment from 10 plants/plot. Injury caused by hurricane winds was most evident in Expt. 1 mostly in stem damage below the soil surface showed callous tissue at the site of injury due to plants being whipped around in the planting hole. Plants rated “best” showed greater plant and root dry weight, stem diameter below the injury point, and higher yield of extra large and total marketable fruit at first harvest than plants rated good or fair. Total marketable yields from rescued plants in Expt. 2 were double than that from replanted plants, and fruit matured 20 days earlier for rescued plants indicating that plants injured by Wilma recovered quickly. Hurricane-damaged crops during 2005–06 in Expts. 3 and 4 yielded 60% lower than that of undamaged crops during 2004–05. In the extra large size category, the yields were reduced between 34% and 12% from the previous season. However, hurricane-damaged loss of yield in the extra large category was offset by increased yield in the medium category. It appears that hurricane-damaged plants, when young, were capable of full recovery and normal yields, whereas hurricane-damaged plants, when older at the time injury occurred, were not able to fully recover and eventually produced only half the normal yield.

Florida is the largest fresh-market tomato (Solanum lycopersicum L.)–producing state in the United States. Although vegetable production requires frequent water supply throughout the crop production cycle to produce maximum yield and ensure high-quality produce, overirrigation can reduce crop yield and increase negative environmental consequences. This study was conducted to evaluate and compare irrigation schedules by a real-time and location-specific evapotranspiration (ET)-based SmartIrrigation Vegetable App (SI) with a historic ET-based schedule (HI). A field study was conducted on drip-irrigated, fresh-market tomato during the Fall of 2015 and Spring of 2016 on a Florida sandy soil. The two scheduling methods (SI and HI) were evaluated for irrigation water application, plant biomass accumulation, nutrient uptake and partitioning, and yield in open-field tomato production. Treatments included 100% HI (T1); 66% SI (T2); 100% SI (T3); and 150% SI (T4). Treatments were arranged in a randomized complete block design with four replicates per treatment during the two production seasons. In both seasons, depth of irrigation water applied increased in the order of T2 < T3 < T1 < T4. Total water savings was greater for T3 schedule compared with T1 schedule at 22% and 16% for fall and spring seasons, respectively. No differences were observed among treatments for tomato biomass accumulation at all sampling periods during both seasons. However, T3 resulted in significantly greater total marketable yield compared with other treatments in both seasons. The impact of irrigation application rate was greater in fruit and leaf nitrogen accumulation compared with that of stem and root biomass. Based on the plant performance and water savings, this study concludes that under a sandy soil condition, a real-time location-specific irrigation scheduler improves irrigation scheduling accuracy in relation to actual crop water requirement in open-field tomato production.

Florida produces the most vegetables in the United States during the winter season with favorable weather conditions. However, vegetables grown on calcareous soils in Florida have no potassium (K) fertilizer recommendation. The objective of this study was to evaluate the effects of K rates on leaf tissue K concentration (LTKC), plant biomass, fruit yield, and postharvest quality of tomatoes (Solanum lycopersicum L.) grown on a calcareous soil. The experiment was conducted during the winter seasons of 2014 and 2015 in Homestead, FL. Potassium fertilizers were applied at rates of 0, 56, 93, 149, 186, and 223 kg·ha⁻¹ of K and divided into preplant dry fertilizer and fertigation during the season. No deficiency of LTKC was found at 30 days after transplanting (DAT) in both years. Potassium rates lower than 149 kg·ha⁻¹ resulted in deficient LTKC at 95 DAT in 2014. No significant responses to K rates were observed in plant (leaf, stem, and root combined) dry weight biomass at all the sampling dates in both years. However, at 95 DAT, fruit dry weight biomass increased with increasing K rates to 130 and 147 kg·ha⁻¹, reaching a plateau thereafter indicated by the linear-plateau models in 2014 and 2015, respectively. Predicted from quadratic and linear-plateau models, K rates of 173 and 178 kg·ha⁻¹ were considered as the optimum rates for total season marketable yields in 2014 and 2015, respectively. Postharvest qualities, including fruit firmness, pH, and total soluble solids (TSS) content, were not significantly affected by K rates in both years. Overall, K rate of 178 kg·ha⁻¹ was sufficient to grow tomato during the winter season in calcareous soils with 78 to 82 mg·kg⁻¹ of ammonium bicarbonate-diethylenetriaminepentaacetic acid (AB-DTPA)-extracted K in Florida.

Determination of nutrient release duration from controlled-release fertilizers (CRFs) or soluble fertilizers encapsulated in polymer, resin, or sulfur covered fertilizer coated with a polymer differs among manufacturers, but may be determined as 75% to 80% nitrogen (N) release at a constant temperature (e.g., 20 to 25 °C). Increases or decreases in temperature compared with the manufacturer release determination temperature increase or decrease CRF N release; thus, coated fertilizer may release more rapidly than stated during the fall season when soil temperatures in seepage-irrigated tomato (Solanum lycopersicum) production can reach 40.1 °C. The objectives of this study were to evaluate N release duration of CRFs by measuring N release from CRFs incubated in pouches under polyethylene mulch-covered raised beds and to determine the CRF duration suitable for incorporation into a fall tomato fertility program. In 2011 and 2013, 12 and 14 CRFs from Agrium Advanced Technologies, Everris, Florikan, and Chisso-Asahi Fertilizer were sealed in fiberglass mesh pouches (12.7 × 14 cm) that were buried 10 cm below the bed surface in a tomato crop grown using commercial production practices. A data logger collected soil temperature 10 cm below the bed surface. Pouches were collected and N content was measured eight times through two fall seasons. A nonlinear regression model was fit to the data to determine N release rate. During the 2011 and 2013 seasons, minimum, average, and maximum soil temperatures were 21.2 and 19.2, 25.7 and 23.5, and 32.2 and 27.7 °C, respectively. Seasonal total CRF N release was between 77.6% and 93.8% during 2011 and 58.3% and 94.3% in 2013. In 2011, PCU90 and in 2013, PCU90 and PCNPK120 had the highest seasonal total percentage N release (PNR) and FL180 had the lowest in both years. A nonlinear regression fit N release from CRF with R ² = 0.85 to 0.99 during 2011 and 0.49 to 0.99 during 2013. Nitrogen release from all CRFs was faster than the manufacturer’s stated release, probably as a result of high fall bed temperatures. A CRF or CRF mixture containing CRFs of 120- to 180-day release duration may be recommended, but the CRFs must release greater than 75% N during the season.

Controlled-release fertilizers (CRFs), a vegetable production best management practice in Florida, are soluble fertilizers (SFs) coated with a polymer, resin, or a hybrid of polymer coating sulfur-coated urea. In 1994, a Controlled Release Fertilizer Taskforce developed an accelerated temperature-controlled incubation method (ATCIM) to predict column-incubated CRF nitrogen (N) release for regulatory purposes. Determination of CRF field N release uses a field method such as a pouch field study, which requires multiple samples and high costs for laboratory N analysis. If the ATCIM may be used to predict CRF N release in the field, then vegetables growers will have a faster and lower-cost method to determine N release compared with the pouch field method. Therefore, the objective of this study was to evaluate the correlation of the ATCIM and the pouch field method as a predictor of N release from CRFs in tomato production in Florida. In 2011 and 2013, 12 and 14 CRFs, respectively, were incubated in pouches placed in polyethylene mulched raised beds in Immokalee, FL, and extracted in the ATCIM during 2013. The ATCIM CRF results were used individually and grouped by release duration to create predicted N release curves in a two-step correlation process. The two-step processes predicted the percentage N release of individual CRF with R ² of 0.95 to 0.99 and 0.61 to 0.99 and CRFs grouped by release duration with R ² of –0.64 to 0.99 and –0.38 to 0.95 in 2011 and 2013, respectively. Modeling CRF N release grouped by release duration would not be recommended for CRF 180-d release (DR), because coating technologies behaviors differ in response to high fall soil temperature in polyethylene mulched beds. However, with further model calibration, grouping CRFs of 90 to 140 DR to simulate the CRF N release profile may allow the ATCIM to predict CRF N release without performing the pouch field method, which currently negated the usefulness of the ATCIM in a tomato production system.

Florida best management practices include the use of controlled-release fertilizers (CRFs), which are soluble nutrients coated with a resin, polymer, sulfur, or a polymer covering a sulfur-coated urea. The purpose of this study was to compare the effects of three CRFs (coated, homogenized NH₄NO₃ and urea, and coated KNO₃) rates in a hybrid CRF/soluble nitrogen fertilizer (SNF) system and two SNF rates [University of Florida/Institute of Food and Agricultural Science (UF/IFAS) and grower standard] on seepage-irrigated fall tomato (Solanum lycopersicum L.) yields, leaf-tissue nitrogen (LTN) concentration, postseason soil nitrogen (N) content, and postharvest fruit quality. Treatments of 112, 168, and 224 kg·ha⁻¹ CRF N plus 56 kg·ha⁻¹ SNF for total N of 168 (CRF112/SNF56), 224, and 280 kg·ha⁻¹ were compared with IFAS (224 kg·ha⁻¹) and grower standard (280 kg·ha⁻¹) of pre-plant SNF. Tomatoes were planted on 29 Aug. 2011 and 3 Sept. 2012 on polyethylene mulch. Air temperature averaged 23.0 and 22.6 °C for the 2011 and 2012 fall seasons with 33.4 and 37.4 cm of rainfall, respectively. Soil temperatures ranged from 15.2 to 40.1 °C in 2011 and 13.6 to 36.6 °C in 2012. Leaf tissue N concentration exceeded the UF/IFAS-recommended sufficiency range for all treatments and sample dates, except CRF112/SNF56 at the last sample date of 2012. There were no differences in extra-large and total marketable yield at first harvest nor in total extra-large yield (three harvests combined) among treatments in 2011; however, total marketable yield for UF/IFAS, CRF112/SNF56, 168/SNF56, and 224/SNF56 was greater than that of the grower standard. In 2012, CRF112/SNF56 and CRF168/SNF56 had the greatest first harvest extra-large and total yield, but there were no differences between season total marketable yields. No differences between treatments were found for total N remaining in the soil postseason in 2011 or 2012. The grower standard, UF/IFAS, and CRF112/SNF56 were firmer at red ripe (less fruit deformation) in 2011, but there were no differences in 2012. In 2011, CRF112/SNF56 and CRF224/SNF56 were rated highest in red color among the treatments, and in 2012 there were no differences. A hybrid system containing lower and equal N rates (112 to 168 kg·ha⁻¹ CRF N and 56 kg·ha⁻¹ SNF56) compared with UF/IFAS-recommended rates produced comparable marketable yield and fruit quality.

Phosphorous (P) has a significant role in root growth, fruit and seed development, and plant disease resistance. Currently, no P fertilizer recommendations are available for vegetables grown on calcareous soils in Florida. The objective of this study was to evaluate the impact of different P rates on leaf tissue P concentration (LTPC), plant growth, biomass accumulation, fruit yield, and postharvest quality of tomato (Solanum lycopersicum L.) grown on a calcareous soil. The experiment was conducted with soils containing 13 to 15 mg·kg⁻¹ of P extracted by ammonium bicarbonate-diethylenetriaminepentaacetic acid (AB-DTPA). Phosphorus fertilizers were applied at rates of 0, 29, 49, 78, 98, and 118 kg·ha⁻¹ of P before laying polyethylene mulch. Tomatoes were grown using drip irrigation during the winter seasons of 2014 and 2015. No significant responses to P rates were found in LTPC during both growing seasons. Plant height, stem diameter, and leaf chlorophyll content at 30 days after transplanting (DAT) were significantly affected by P rates in 2015, but not in 2014. The responses of plant biomass were predicted by linear models at 60 DAT in 2014 and at 30 DAT in 2015. There were no significant differences in plant biomass at 95 DAT in both years. At the first and second combined harvest, the extralarge fruit yield was unaffected in 2014, but predicted by a quadratic-plateau model with a critical rate of 75 kg·ha⁻¹ in 2015. The total season marketable yields (TSMY) and postharvest qualities were not significantly affected by P rates in either year. Phosphorous rate of 75 kg·ha⁻¹ was sufficient to grow a tomato crop during the winter season in calcareous soils with 13–15 mg·kg⁻¹ of AB-DTPA-extractable P.

Florida had the largest fresh-market tomato (Solanum lycopersicum L.) production in the United States, with a value of $437 million and 13,355 ha harvested in 2014. Despite the development of Best Management Practices (BMPs) and University of Florida/Institute of Food and Agricultural Sciences (UF/IFAS) fertilizer recommendations, tomato growers often use fertilizer rates above the recommended ones, especially when seepage irrigation is used and a longer growing season is foreseen. If a mass balance of N–P–K partitioning could be made in field conditions, a better understanding of nutrition applications could be reached. Therefore, a field study was conducted on seepage-irrigated tomato on a commercial farm in southwest Florida, during the spring and winter season of 2006 to evaluate the nitrogen (N) rate and season effects on tomato plant growth, fruit yield, N, phosphorous (P), and potassium (K) accumulation and use efficiency. The UF/IFAS N-recommended rate (224 kg·ha⁻¹) was compared with a commercial grower (CG) rate (358 kg·ha⁻¹). Both N rates were incorporated at bedding with 61 and 553 kg·ha⁻¹ of P and K, respectively. Fruit yield and plant growth were measured and roots, stems, leaves, and fruit samples were analyzed to determine total N, P, and K content and accumulation in different plant parts. Nutrient recovery (REC) and the partial factor of productivity of applied nutrients (PFP) were calculated for each N rate. In the spring, 120 days after transplanting, plants dry biomass was 11.5% higher (P = 0.01) in the CG N rate than with UF/IFAS N rate, while no significant differences were observed in the winter season. In the spring, N, P, and K accumulation were 250, 56, and 285 kg·ha⁻¹ in plants grown with CG N rate and were significantly lower (23%, 5%, and 23%, respectively) with the UF/IFAS N rate, respectively. In the winter, total N accumulation was 231 kg·ha⁻¹ in plants fertilized at CG N rate and significantly lower (16%) with the UF/IFAS N rate. N rate did not significantly affect P and K accumulation, which were on average 64 and 312 kg·ha⁻¹, respectively. Marketable fruit yield was significantly higher (P = 0.03) with CG N rate than with UF/IFAS N rate (91.1 vs. 81.5 Mg·ha⁻¹), and was significantly higher (P = 0.03) in the spring than in the winter (100.8 vs. 71.8 Mg·ha⁻¹). The N_REC was significantly higher (P = 0.01) with the UF/IFAS N rate than with CG N rate and was not significantly affected (P = 0.94) by seasons. The PFP_N was significantly higher (P = 0.001) with the UF/IFAS N-rate than with CG N-rate, and was significantly higher (P = 0.04) in the spring than in the winter season. These results suggest that current UF/IFAS N recommendations are more conservative of N and this should lead to reduced leaching potential but, UF/IFAS recommendations must be season specific due to the difference in environmental conditions of fruit maturation in cooler weather of the winter season compared with a warmer environment of the spring season.

Florida tomato growers generate about $600 million of annual farm gate sales. The Florida Vegetable and Agronomic Crop Water Quality/Quantity Best Management Practices Manual was adopted by rule in the Florida Administrative Code in 2006 and describes cultural practices available to tomato growers that have the potential to improve water quality. By definition, BMPs are specific cultural practices that are proven to optimize yield while minimizing pollution. BMPs must be technically feasible, economically viable, socially acceptable, and based on sound science. The BMP manual for vegetables endorses UF-IFAS recommendations, including those for fertilization and irrigation. Current statewide N fertilizer recommendations for tomato provide for a base rate of 224 kg/ha plus provisions for supplemental fertilizer applications 1) after a leaching rain, 2) under extended harvest season, and 3) when plant nutrient levels (leaf or petiole) fall below the sufficiency range. An on-farm project in seven commercial fields was conducted in 2004 under cool and dry growing conditions, to compare grower practices (ranging from 264 to 468 kg/ha of N) to the recommended rate. Early and total extra-large yields tended to be higher with growers' rate than with the recommended rate, but these differences were significant only in one trial. The first-year results illustrated the need for recommendations to be tested for several years and to provide flexibility to account for the reality of local growing conditions. Working one-on-one with commercial growers provided an opportunity to focus on each farm`s educational needs and to identify specific improvements in nutrient and irrigation management.