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Eric H. Simonne and Chad M. Hutchinson

Best management practices (BMPs) for vegetable crops are under development nationwide and in Florida. One goal of the Florida BMP program is to minimize the possible movement of nitrate-nitrogen from potato (Solanum tuberosum) production to surface water in the St. Johns River watershed without negatively impacting potato yields or quality. Current fertilizer BMPs developed for the area focus on fertilizer rate. Controlled-release fertilizers (CRF) have long been a part of nutrient management in greenhouse and nursery crops. However, CRFs have been seldom used in field-vegetable production because of their cost and release characteristics. Nutrient release curves for CRFs are not available for the soil moisture and temperature conditions prevailing in the seepage-irrigated soils of northern Florida. Controlled-leaching studies (pot-in-pot) in 2000 and 2001 have shown that plant-available nitrogen (N) was significantly higher early in the season from ammonium nitrate, calcium nitrate and urea compared to selected CRFs. However, N release from off-the-shelf and experimental CRFs was too slow, resulting in N recoveries ranging from 13% to 51%. Cost increase due to the use of CRFs for potato production ranged from $71.66 to $158.14/ha ($29 to $64 per acre) based on cost of material and N application rate. This higher cost may be offset by reduced application cost and cost-share pro-grams. Adoption of CRF programs by the potato (and vegetable) industry in Florida will depend on the accuracy and predictability of N release, state agencies' commitment to cost-share programs, and CRFs manufacturers' marketing strategies. All interested parties would benefit in the development of BMPs for CRFs.

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Eric H. Simonne and Monica Ozores-Hampton

With the development and implementation of best management practices (BMP), extension educators are facing a new and unexpected combination of challenges and opportunities. Because the BMP mandate requires a combination of research, demonstration, and outreach, it may affirm the relevance of the land grant mission in the 21st century, engage universities in interagency alliances, and help rediscover the wonders of the proven extension method. The extension approach to water and nutrient management needs to shift from “pollute less by applying less fertilizer” to “pollute less by better managing water.” Applied research is leading to advances in areas such as nutrient cycles and controlled-release fertilizers. At the same time, universities need to walk a fine line between education and regulation, address perennial issues of overfertilization, and consider the reformulation of recommendations that are now used in a quasi-regulatory environment. A combination of education, consensus, and novel approaches is needed to adapt the rigor of research to a multitude of growing conditions and risks of nutrient discharge in order to comply with U.S. federal laws and restore water quality.

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Christopher A. Frank, Robert G. Nelson, Eric H. Simonne, Bridget K. Behe, and Amarat H. Simonne

Most bell peppers (Capsicum annuum L.) produced and consumed are green. However, yellow, red, orange, white, black, and purple bell peppers are also available. While bell pepper consumption in the United States has been increasing in the past 10 years, limited information is available on how their color, retail price, and vitamin C content influence consumer preferences. A conjoint analysis of 435 consumer responses showed that, for the total sample, color was about three times more important than retail price in shaping consumers' purchase decisions, while vitamin C content was nearly irrelevant. Six distinct consumer segments were identified through cluster analysis. Four segments favored green peppers, while one segment favored yellow and one favored brown. Demographic variables generally were not good predictors of segment membership, but several behavioral variables, such as past bell pepper purchases, were significantly related to segment membership. While green is generally the preferred color, market segments exist for orange, red, yellow, and even brown peppers. Applications to marketing strategies suggested that price sensitivity could explain why green peppers were priced individually, but those of other colors were priced by weight, and that promotion of increased vitamin C content would be most effective if associated specifically with yellow and orange peppers.

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Eric H. Simonne, Amarat H. Simonne, Larry W. Wells, Marvin E. Ruf, and John T. Owen

While lettuce is one of the most widely consumed vegetables in the United States, production is mainly concentrated in the western states. This research investigated the feasibility of lettuce production in the Southeast (SE), where downy mildew, tip burn, bitterness, bolting, and postharvest handling are potential production problems. Lettuce varieties were evaluated on plastic mulch and drip irrigation under several growing conditions. Cultivar and location significantly (P < 0.01) affected yield and transplant survival rate. Following these tests, 'Salinas 88 Supreme', 'Legacy', 'Bullseye', 'Epic' (crisphead); 'Nancy', 'Nevada', 'Ostinata' (butterhead); 'Parris Islands', 'Augustus' (Romaine); and 'Red Salad Bowl', 'Red Prize', and 'Slobolt' (loose leaf) are considered best-performing lettuce varieties for Alabama. These results, along with bitterness evaluation, support the potential for lettuce production in the SE.

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Amarat H. Simonne, Eric H. Simonne, Ronald R. Eitenmiller, John Owen, and Larry Wells

The main limiting factor to lettuce production in the Southeast is bitterness. Bitterness in lettuce is associated with sesquiterpene lactones, a bitter principles of the latex of wild lettuce species Lactuca virosa or L. sativa. These wild species are used as parents in the development of virus-resistant cultivars. This study evaluated bitterness of 18 commercial cultivars of lettuce grown following recommended production practices at two locations. Lettuce was hand harvested, refrigerated, washed, and cut into bite-size pieces. Samples were served one by one to a group of 15 panelists, trained with caffeine solutions of increasing bitterness scores (BS; 0% = 0, 0.05% = 2, 0.08% = 5, 0.15% = 10, and 0.20% = 15). A BS of less than seven was acceptable. BS was significantly (P < 0.02) different among varieties. Varieties with lowest BS were `Epic', `Salinas 88 Supreme', `Nevada', `Red Prize', and `Legacy'. For these varieties, mean, most frequent, and highest BS were less than seven. This study suggests that it is possible to grow nonbitter lettuce in the Southeast.

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Eric H. Simonne, Joseph M. Kemble, and Doyle A. Smittle

The effect of irrigation scheduling method (variable crop factor, 1; constant crop factor, 2; empirical, 3), soil water tension (25, 50, 75kPa SWT), tillage (disc arrow, DA, moldboard plow, MP) and planting dates (PD) on total irrigation (TI), number of irrigations (NI), useful (UR) and lost rainfall (LR) was studied using a Pascal program that simulated water budgets of 720 crops of snap bean over 10 years. NI and TI were significantly (p<0.01) lower with met.1. Met.3 had the lowest LR and highest UR, but did not allow the complete calculation of the water balance. TI was significantly higher at 25kPa. MP tillage requested fewer NI and less TI, had lower LR and higher UR. Early PD requested fewer NI and TI, and had higher LR. Hence, when water supply was not limiting and weather data were available, a combination of Met.1, MP at any PD provided a continuous supply of water to the crop while controlling water deficit.

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Michela Farneselli, David W. Studstill, Eric H. Simonne, and Bob Hochmuth

The quantitative assessment of nitrate-nitrogen (NO3-N) leaching below the root zone of vegetable crops grown with plasticulture (called load) may be done using deep (150-cm) soil samples divided into five 30-cm long subsamples. The load is then calculated by multiplying the NO3-N concentration in each subsample by the volume of soil (width × length × depth, W × L × D) wetted by the drip tape. Length (total length of mulched bed per unit surface) and depth (length of the soil subsample) are well known, but W is not. In order to determine W at different depths, two dye tests were conducted on a 7-m deep Lakeland fine sand using standard plasticulture beds. Dye tests consisted in irrigating for up to 38 and 60 hours (11,756 and 18,562 L/100 m of irrigation, respectively), digging transverse sections of the raised beds at set times and taking measurements of D and W at every 30-cm. Most dye patterns were elliptic elongated. Maximum average depths were similar (118 and 119 cm) for both tests despite differences in irrigation duration and physical proximity of both tests (100 m apart in the same field). Overall, D response (cm, both tests combined) to irrigation volume (V) was quadratic (Dcomb.avg = –2 × 10–7V2 + 0.008V + 34), and W responses (applying maximum and average values, Wmax and Wmean) to D (cm) were linear (Wmax = –0.65D+114: Wmean = –0.42D + 79). Predicted Wmax were 104, 84, 64, 44, and 25 cm at 30-cm depth increments. These preliminary values may be use for load calculations, but are likely to over-estimate load as they were determined without transpiring plants and may need to be adjusted for different soil types.

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Clyde W. Fraisse, Zhengjun Hu, and Eric H. Simonne

Most of the winter vegetable production in the southeastern United States is located in Florida. High-value vegetable crops are grown under intensive fertilization and irrigation management practices using drip, overhead, or seepage irrigation systems. Rainfall events may raise the water table in fields irrigated by seepage irrigation resulting in leaching of nutrients when the level is lowered to remove excess water. The objective of this study was to assess the effect of El Niño–Southern Oscillation (ENSO) phases on rainfall distribution and leaching rain occurrences during the fall, winter, and spring tomato (Solanum lycopersicum) growing seasons using long-term weather records available for main producing areas. Differences in fall growing season mean precipitation during El Niño, La Niña, and neutral years were found to be nonsignificant. Winter and spring mean precipitations during El Niño, La Niña, and neutral years were found to be significantly different. Winter and spring average rainfall amounts during La Niña and neutral years were lower than during El Niño years. During El Niño years, at least one leaching rainfall event of 1.0 inch or more in 1 day occurred at all locations and all planting seasons and two of these events occurred in more than 9 of 10 years except during the winter and spring planting seasons at the Tamiami Trail station located in Miami–Dade County. During the fall growing season of El Niño years, three to four 1.0 inch or more in 1-day leaching rainfalls may be expected at least 4 of 5 years at all locations. In the case of larger leaching rainfall events (3.0 inches or more recorded in 3 days or 4.0 inches or more recorded in 7 days), the probability of having at least one event was mostly less than 0.80. Based on these results, nitrogen fertilizer supplemental applications of 30 to 120 lb/acre could be applied during the fall growing season of all ENSO phases and during all planting seasons of El Niño years. Using current fertilizer prices, one supplemental fertilizer application of 30 lb/acre nitrogen and 16.6 lb/acre potassium costs $55/acre. Assuming a median wholesale price of $12 per 25-lb box, this additional cost may be offset by a modest yield increase of 4.6 boxes/acre (compared with a typical 2500 25-lb box/acre marketable yield). These results suggest that ENSO phases could be used to predict supplemental fertilizer needs for tomato, but adjustments to local weather conditions may be needed.

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Richard V. Tyson, Danielle D. Treadwell, and Eric H. Simonne

Aquaponics combines the hydroponic production of plants and the aquaculture production of fish into a sustainable agriculture system that uses natural biological cycles to supply nitrogen and minimizes the use of nonrenewable resources, thus providing economic benefits that can increase over time. Several production systems and media exist for producing hydroponic crops (bench bed, nutrient film technique, floating raft, rockwool, perlite, and pine bark). Critical management requirements (water quality maintenance and biofilter nitrification) for aquaculture need to be integrated with the hydroponics to successfully manage intensive aquaponic systems. These systems will be discussed with emphasis on improving sustainability through management and integration of the living components [plants and nitrifying bacteria (Nitrosomonas spp. and Nitrobacter spp.)] and the biofilter system. Sustainable opportunities include biological nitrogen production rates of 80 to 90 g·m−3 per day nitrate nitrogen from trickling biofilters and plant uptake of aquaculture wastewater. This uptake results in improved water and nutrient use efficiency and conservation. Challenges to sustainability center around balancing the aquaponic system environment for the optimum growth of three organisms, maximizing production outputs and minimizing effluent discharges to the environment.

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Eric H. Simonne, Joseph M. Kemble, and Doyle A. Smittle

A TurboPascal computer program was developed to calculate daily water budgets and schedule irrigations. Daily water use (di) is calculated as pan evaporation (Ep) times a crop factor (CFi), where i is crop age. The water balance uses a dynamic rooting depth, the soil water holding capacity (SWC) and rainfall data (Ri). di is added to the cumulative water use (Di-1) and Ri is subtracted from Di. An irrigation in the amount of Di is recommended when Di approximates allowable water use. The program cart be adapted to most crop and soil types, and can be used for on-time irrigation scheduling or for simulating water application using past or projected weather data. This program should increase the acceptance of modem scheduling irrigation techniques by farmers and consultants. Additionally, this program may have application in an overall water management programs for farms, watersheds or other areas where water management is required.