Search Results

You are looking at 1 - 8 of 8 items for :

  • Author or Editor: Jerry Sartain x
  • HortTechnology x
Clear All Modify Search

Florida's citrus (Citrus spp.), vegetable, and turfgrass industries must improve nitrogen (N) and phosphorus (P) fertilizer use efficiency to remain sustainable in an era of emerging environmental policies designed to protect water quality. Producers have traditionally used water-soluble N and P fertilizers because they are plentiful and economical. Improving nutrient use efficiency (NUE) is being addressed through implementation of best management practices (BMPs) such as nutrient management planning, proper fertilizer material selection, better application timing and placement, and improved irrigation scheduling. Emerging technology that will aid in this effort includes increased use of enhanced efficiency fertilizers (EEFs), organic soil amendments, fertigation, and foliar fertilization. However, any new technology shown to improve NUE must be economically feasible before it can be considered a BMP. Future research in this area will aim to improve the economics of EEFs and precision fertilizer application.

Full access

Best management practices (BMPs) for Florida's green industries have been established since 2002. BMPs for nonagricultural industries such as commercial lawn care were developed in 2002 by the Florida Department of Environmental Protection (FDEP), the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS), and other parties. The BMP educational program, delivered primarily by UF/IFAS extension in partnership with the FDEP, began in 2003 as a voluntary program. As a result of increasing concerns regarding lawn fertilization and potential harmful effects on ground and surface waters, several local governments throughout the state require commercial fertilizer applicators to have a certificate of completion in a BMP educational program. The BMP program emphasizes appropriate fertilization practices to reduce nonpoint source pollution, including proper rates, timings, and application of fertilizers. Research done on fate of fertilizer applied to turfgrass demonstrates that a properly maintained lawn provides an effective means for uptake of nutrients. Some of the factors that have been shown through research to increase the opportunity for nutrient leaching include nitrogen (N) application at higher than recommended rates, excess rainfall after fertilization, and fertilization at a time when turf is not actively growing. Research results vary regarding N source and the difference in nitrate leaching resulting from N source. To provide concise research-based information for lawmakers and elected officials in Florida, there is currently a large research project underway to further quantify nutrient leaching under a variety of circumstances. Results of this research should form the basis for future regulations regarding fertilizer applications.

Full access

Reclaimed water (RW) is increasingly viewed as a valuable resource for supplying irrigation water and nutrients for landscape plants growing in urban environments. A greenhouse experiment was conducted to determine if nitrogen (N) in RW contributes significantly to turfgrass plant nutrition and to measure N use efficiency and the effects of irrigation with RW on N leaching. The factorial experiment was replicated four times and conducted in a greenhouse on the University of Florida campus for 1 year using ‘Floratam’ st. augustinegrass (Stenotaphrum secundatum) and ‘Empire’ zoysiagrass (Zoysia japonica). Treatments included irrigation with tap water (control), irrigation with RW from University of Florida wastewater treatment facility, irrigation with RW with additional N supplied from ammonium nitrate to achieve 5, 9, and 13 mg·L−1 N solutions, and a dry prilled fertilizer treatment based on the recommended N application rate for turfgrass in northern Florida. The average total N and phosphorus (P) concentrations of RW, based on 1 year weekly monitoring were 3.31 mg·L−1 total N with 2.14 mg·L−1 nitrate-N and 0.46 mg·L−1 ammonium-N, and 2.00 mg·L−1 P composed of 1.92 mg·L−1 orthophosphate. Turfgrass growth responded positively (P < 0.05) to N concentration in the irrigation water. The concentration of N in the unamended university campus RW was not sufficient for optimal turfgrass growth. Grass quality and turfgrass clippings yield maximized when the total N concentration in the irrigation water was at least 5 mg·L−1. Turfgrass receiving dry synthetic N fertilizer resulted in greater growth and 2-fold greater N leaching than with the remaining treatments for both turf types. The highest N recovery percentage for both turf types was found when the N concentration in the solution was 5 mg·L−1.

Full access

Degraded inland and coastal water quality is a critical statewide concern in Florida and other states. Nutrients released from land-based human activities are present in water bodies resulting in algal blooms and increased eutrophication that impairs water bodies for their intended uses. There are differing approaches to addressing eutrophication, including voluntary adoption of current best management practices (BMPs) for nutrients, state regulation, or local county or municipal ordinances. The local ordinance, some including a summer (or so-called “wet season”) fertilizer ban or “blackout,” has been the chosen approach in some Florida counties and municipalities to address local water quality issues. Many components of these ordinances follow published BMPs, and there is agreement in the literature on the effectiveness of these practices for preventing nutrient losses from the landscape. However, there has been disagreement among stakeholders regarding the inclusion of a total fertilizer ban in a local ordinance. Regulators are asking about the best approach to controlling urban pollution and if banning fertilizer in the growing season would achieve the desired environmental protection and whether there are any potential unintended consequences associated with removing fertilizer from turfgrass growing in the summer months. The scientific literature documents the nature and scope of the water pollution problem, and numerous research reports have addressed fertilizer BMPs to prevent nutrient losses from the landscape. This article discusses the increased rate of eutrophication and reviews the pertinent national literature regarding managing urban landscape fertilization to protect water quality. Particular attention is given to fertilization practices during the active landscape plant (especially turfgrass) growth period that corresponds to the summer fertilizer bans in some Florida local ordinances. Therefore, special attention is paid to the question of what information is in the scientific literature and whether a fertilizer ban is the best way of achieving the goal of improving urban water quality. Research summarized in this review points to potential unintended consequences of increased nutrient losses from urban landscapes, particularly turfgrass, when proper, recommended fertilization and irrigation practices are not followed.

Full access

Slow-release fertilizers marketed to the public usually include a claim that nutrient release will last for a specific time period (e.g., 6, 9, or 12 months). However, no official laboratory method exists that can verify these claims. A long-term (180 days) incubation method has been developed that produces constants for an exponential model that characterizes nutrient release as a function of time. In addition, a relatively short-term (74 h) extraction method has been developed to assess nutrient release under accelerated laboratory conditions. Through regression techniques, release constants established for individual slow-release nutrient sources by the incubation method are used in conjunction with the laboratory extraction data to verify the release claims of slow-release fertilizers. Nutrient release for selected single materials has been predicted with greater than 90% accuracy in previous studies. Nutrient release from mixtures of slow-release products has been more variable. It is typical for water-soluble and slow-release fertilizers to be mixed in commercial products. Ultimately, it is intended that these methodologies will be accepted as an official method to verify nutrient release claims placed on slow-release fertilizers.

Free access

Applying water-soluble nitrogen (N) fertilizer to Florida citrus (Citrus spp.) trees on deep sandy soils may lead to poor nutrient use efficiency and possible nitrate contamination of groundwater if rainfall or irrigation is excessive. Controlled-release fertilizer (CRF) is a possible alternative to increase N uptake efficiency and minimize losses to the environment, but current grower acceptance is limited as a result of lack of experience with CRF performance and its high relative cost. The objective of this study was to measure the N release characteristics of a CRF blend (CitriBlen®) designed for mature Florida citrus trees and its three CRF components [Agrocote® Type A, Agrocote® Type C(D), and Agrocote® Poly-S®] under laboratory and field conditions. We first characterized N release from these CRF materials using a 270-day laboratory soil incubation. The quantity of N released was influenced by CRF material used; after 270 days, cumulative leached N recoveries were 90%, 82%, 85%, and 69% of the total N applied as CitriBlen®, Agrocote® Type A, Agrocote® Type C(D), and Agrocote® Poly-S®, respectively. We then measured the N release patterns of the fertilizers in a 1-year field evaluation and developed their N release curves. Studies were simultaneously conducted in central and southwestern Florida. Mesh bags containing 3.5 g of elemental N from each source were placed on the soil surface within the irrigated zone under a citrus tree canopy to estimate N release rates from the fertilizers. Despite differential N release rates between locations, at 1 year, the rank of N release was Type A > CitriBlen® > Poly-S® > Type C(D). CitriBlen® N release patterns matched well with the current University of Florida, Institute of Food and Agricultural Sciences citrus fertilization strategy recommended as a best management practice.

Full access

Urban watersheds include extensive turfgrass plantings that are associated with anthropocentric attitudes toward landscapes. Native and construction-disturbed urban soils often cannot supply adequate amounts of nitrogen (N) and phosphorus (P) for the growth and beauty of landscape plants. Hence, fertilization of landscape plants is practiced. Mismanaged fertilization and irrigation practices represent a potential source of nutrients that may contribute to water quality impairment. This review focuses on turfgrass fertilization practices and their impacts on urban water quality. Research results show that fertilization during active growth periods enhances turfgrass nutrient uptake efficiencies. The major concern regarding the fertilization of turfgrass and landscape plants in urban watersheds, therefore, is selecting the proper combination of fertilizer rate, timing, and placement that maximizes nutrient utilization efficiency and reduces the risk for nutrient loss to water bodies. Encouraging individuals to adopt best management practices (BMPs) is a priority for watershed managers. Research has found that educational programs are an important part of changing fertilization habits and that education needs to be thorough and comprehensive, which is beyond the scope of many seminars and fact sheets currently in use.

Free access

Urban water quality management is becoming an increasingly complex and widespread problem. The long-term viability of aquatic ecosystems draining urban watersheds can be addressed through both regulatory and nutrient and water management initiatives. This review focuses on U.S. regulatory (federal, state, and local) and management (runoff, atmospheric deposition, and wastewater) impacts on urban water quality, specifically emphasizing programs in Florida. Because of rapid population growth in recent decades, and projected increases in the future, appropriate resource management in Florida is essential. Florida enacted stormwater regulations in 1979, before the U.S. Environmental Protection Agency (USEPA) amended the Clean Water Act (CWA) to regulate stormwater discharges. However, in the United States, more research has been conducted on larger structural best management practices (BMPs) (e.g., wet ponds, detention basins, etc.) compared with smaller onsite alternatives (e.g., green roofs, permeable pavements, etc.). For atmospheric deposition, research is needed to investigate processes contributing to enhanced deposition rates. Wastewater (from septic systems, treatment plants, and landfills) management is especially important in urban watersheds. Failing septic systems, elevated nutrient concentrations in discharged effluent, and landfill leachate can all potentially degrade water quality. Proposed numeric nutrient criteria from the USEPA and innovative technologies such as bioreactor landfills are emergent regulatory and management strategies for improved urban water quality.

Full access