Tag Archive: Fertilizer

Evaluation of ESN Controlled Release Fertilizer for Florida Corn Production

Environmentally Smart Nitrogen (ESN) corn trial at the UF/IFAS West Florida Research and Education Center in Jay, FL. Photo: Mike Mulvaney

Dr. Michael J. Mulvaney, Cropping Systems Specialist, WFREC, Jay, FL

Now is the time to start thinking about nitrogen (N) management strategies for corn production in the Panhandle.  This is a follow-up to the March 2016 article:  Environmentally Smart Nitrogen (ESN) as a Controlled-release Nitrogen source for Cotton, or ESN for cotton production.  Researchers now have data on the use of ESN for corn production in Florida.

ESN is a polymer-coated urea formulated as 44-0-0. The reason it contains 2% less N than urea (which is 46-0-0) is due to the weight of the polymer coating.  ESN is commercially available in bulk in some parts of the Panhandle.  Many growers blend ESN with urea, commonly as a 50-50 mix, with the idea that some N is immediately available, while the rest will release slowly over time to “spoon feed” the crop.

How slowly does ESN release N?

The release of N from ESN is temperature dependent under controlled conditions.  That is, the higher the temperature, the faster the release.  So, it stands to reason that ESN release should be slower at corn pre-plant as compared to corn sidedress application.  Likewise, we should see different N release if we broadcast as compared to incorporating ESN.  UF Researchers took this out of the lab, and measured the release rates under field conditions at Jay and Citra, FL during the 2015 and 2016 growing seasons.

The Florida data showed that ESN releases 50% N in approximately 2-5 weeks, with broadcast applications releasing N slower than incorporated ESN.

But does it make a difference in yield?

We used different ESN:urea blends at different times (all pre-plant, or 25% N pre-plant with 75% N sidedress) under corn production at two sites across the Panhandle during 2015 and 2016.  These corn trials were all fertilized at 183 lbs N/ac (except the control, of course) – the only differences were in how it was applied.

Figure 1. Corn grain yields using various ESN:urea blends, applied either all pre-plant or using a 25% N pre-plant, 75% N sidedress split application. 183 lbs N/ac were applied to all plots except the control.

Yield differences were not statistically significant among any of the application treatments.


Global urea prices are near 5-year lows, but are about the same price as last year (Figure 2).  Locally sourced urea in March of 2016 was selling at $ 380/ton, and ESN was $ 600/ton.  That’s a 65% increase per unit of N for ESN over urea.  March 2015 prices were $ 560/ton urea and $ 687/ton ESN, an increase of 28% per unit of N over urea.  It is expected that prices in March 2017 will be slightly higher those in March 2016.

Figure 2. Global urea prices over the past five years.

Break even cost

If corn prices are $ 3.60/bushel, and 200 lbs N were applied, you would need a 15 bu/ac yield increase to break even for the additional cost of ESN over urea.  If only half of the N was applied as ESN, a 7.5 bu/ac yield increase would be needed to break even.


During corn production in the Florida Panhandle, 50% of N release can be expected in 2-5 weeks, depending on timing and placement. Although controlled release of N may lead to increased N use efficiency, there was no evidence of significant yield differences among blends, or timing of applications when applied at 183 lbs N/ac at either Jay, FL (a sandy loam) or Citra, FL (sand).

Advantages over urea:

  • It may limit the opportunity for N loss through volatilization, which may be useful under certain conditions where urea-N loss can be high (warm, moist, broadcast conditions). Research on N volatilization from ESN is underway through Dr. Cheryl Mackowiak’s program.
  • It stores better than urea. It won’t gum up unless prills are broken.

Disadvantages compared to urea:

  • It currently costs 65% more per unit of N than urea.
  • In a heavy rainfall, broadcast ESN can be pushed into low spots in the immediate area. You can incorporate ESN to help avoid this, particularly if you are on a slope.
  • ESN should be handled with reasonable care. Damaged prills are as good as urea but considerably more expensive. When the front-end loader scoops from the bottom of the pile, significant damage can occur to the polymer coating.  Also, broadcast applications can damage prills with contact to spreader fins.  Incorporation of ESN may damage prills as well, which may explain why incorporated N release was faster than broadcast N release.

    ESN prills washed into localized low spots after a heavy rain in 2016. Photo: Mike Mulvaney


Author: Michael Mulvaney – m.mulvaney@ufl.edu

Cropping Systems Specialist, University of Florida, West Florida Research and Education Center, Jay, FL. Follow me @TheDirtDude

Michael Mulvaney

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2017/01/13/evaluation-of-esn-controlled-release-fertilizer-for-florida-corn-production/

February is not “Fertilizer Time” for Lawns

February is not “Fertilizer Time” for Lawns


Image courtesy UF / IFAS Florida Friendly Landscaping

Image courtesy UF / IFAS Florida Friendly Landscaping

It’s too early to fertilize our warm-season lawn grasses now. This includes the use of fertilizers contained in weed-and-feed products.

There are a number of reasons why it’s best to wait to fertilize your lawn.

First, the soil temperature is too cool for grass roots to have access to some of the fertilizer elements. For example, iron and potassium are poorly available until the soil warms up in spring. Some nutrients leach below the grass roots because the lawn can’t use them yet. This results in waste of fertilizer, time and money.

Secondly, fertilizing too soon can induce nutrient deficiencies and off color areas in your lawn. This is one cause for bright yellow areas in lawns during early spring. Nitrogen is readily taken up by the lawn, even under cool soil conditions, and stimulates early green growth. Early lawn growth is dependent on iron also being readily available. However, iron is poorly available under the cool soil conditions of late winter and early spring. Therefore lawns turn yellow in areas due to an iron deficiency caused by an early fertilizer application. Many times, as soil temperatures warm during mid April and May, the iron becomes available and the lawn turns green. So why not avoid this scenario by waiting until mid April to fertilize your lawn?

It takes consistently warm night temperatures to allow the soil to become warm enough for best root growth and optimal uptake of fertilizer.

Thirdly, the young, tender grass roots that are beginning to grow in early spring are easily burned by the fertilizer.

Fourthly, fertilizing too early can stimulate early lawn growth, which is tender and easily injured by a late frost. The average date for our last killing frost is mid March.

Also, be very cautious about using weed-and-feed products that recommend a late winter application. These products are usually high in nitrogen, which will cause your lawn to begin growing too early. If you’re trying to control weeds, it’s best to apply your herbicides separately from fertilizer, anyway.

In North Florida, it’s best to wait until your lawn has completely greened up in spring before applying any fertilizer.

Waiting allows for more efficient use of the fertilizer. You will not injury you lawn by waiting to fertilize but you can certainly injure your lawn by fertilizing too early.

So, have patience, allow your lawn to green up on its own and then fertilize, even if it’s not until mid April or May.


Author: Larry Williams – llw5479@ufl.edu

Larry Williams is the County Extension Director and Residential Horticulture Agent for the UF/IFAS Extension Office in Okaloosa County.

Larry Williams

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2016/02/11/february-is-not-fertilizer-time-for-lawns/

Fertilizer Basics for Pastures and Hay Fields

Fertilizer Basics for Pastures and Hay Fields

Pasture Fertilization Demo highlighting different sources.

Pasture Fertilization Demonstration highlighting different sources.

Soil fertility and plant nutrient management is an important part of agroecosystems. Agroecological approaches to soil fertility and nutrient management begin with soil testing. A soil test will tell you soil pH. Soil pH affects the availability of nutrients to the plant. Soil pH should be adjusted to the optimal level for each crop before adding other fertilizers. A relatively new approach to fertilizer best management practices is to apply fertilizers considering the 4 Rs – Right Rate, Right Time, Right Place, Right Source.


Right rate

The right rate will be determined by evaluating several factors and environmental conditions. Producers should always start with a soil test to determine current plant available nutrient levels in the soil. The UF/IFAS fertilizer recommendation will be based on the plant available nutrients in the soil and the plant nutrient demand. Producers should also consider the nutrient sources and their predicted use efficiencies. Lastly, producers should consider how nutrients will be removed or recycled on the farm. More nutrients are recycled on grazed pastures and more nutrients are removed on hay fields. Therefore hay fields will require more nutrient inputs to offset the nutrient outputs coming off the farm as hay.

Right time

Producers will consider the rate, source and place of application again when deciding when to apply fertilizers to hay fields or pastures. Nutrients should be applied when plants are actively taking up nutrients from the soil. This will be dependent on plant species, variety and planting date. Also, predictable weather patterns affect the timing of fertilizer applications. Periods of high rainfall should be avoided because nutrient leaching losses will be higher. Overall farm logistics also should be considered. Split applications of conventional sources are best to decrease nutrient losses but not always logistically and economically possible.

Right place

The source, rate and timing of application should be considered when deciding on placement of fertilizers on the farm. Also, producers should consider root depth, soil chemical reactions and tillage systems. For perennial pastures, fertilizers are applied on the soil surface rather than incorporated into the soil subsurface. This affects how the fertilizers become available to the plant and how the nutrients become susceptible to losses. The goal of fertilizing pastures and hay field should be to optimize that amount of nutrients that are available to the plant in the root zone but to decrease nutrient losses due to leaching.

Right source

Producers will need to consider desired rates, timing and place of applications when deciding what source of fertilizers to use. The goal is choosing a source that will provide plant available nutrients when the plants are actively taking up nutrients while decreasing nutrient losses to the environment. Nutrients include macronutrients and micronutrients. Producers should apply balance nutrients to meet the crop demands. Producers are forced to choose sources by what is commercially available to them. The main sources of nitrogen commercially available to producers in Northwest Florida currently are urea, controlled release fertilizers (polycoated ureas and inhibitor additives with urea) and slow release fertilizers (biosolids).


For more specific forage fertilization recommendations, download:

Fertilizing and Liming Forage Crops

The Four Rs of Fertilizer Management



Author: Jennifer Bearden – bearden@ufl.edu

Agriculture Agent Okaloosa County

Jennifer Bearden

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2014/11/15/fertilizer-basics-for-pastures-and-hay-fields/

New Year Brings New Fertilizer Regulations

New Year Brings New Fertilizer Regulations

Beginning New Year’s Day of 2014, a new law went into effect that state lawmakers, environmental advocates, and lawn care professionals hope will reduce Florida’s decades-long problem with stormwater runoff pollution.  The law states that all lawn care professionals applying fertilizer as part of their business must pass a Green Industries Best Management Practices (GI-BMP) test and receive a certification commonly referred to as a “fertilizer license.” The Florida Departments of Agriculture and Consumer Services and Environmental Protection maintain the records and regulatory authority over these licenses.

Lawn care service providers applying fertlizer to Florida landscapes are now required to complete best management training. Photo credit: UF IFAS

Lawn care service providers applying fertilizer to Florida landscapes are now required to complete best management training. Photo credit: UF IFAS

Fertilizer becomes a problem in the environment when either too much is applied or it is used at the incorrect rate or wrong time.  Rain or irrigation water can move these nutrients (remember, fertilizer is mostly composed of nitrogen, potassium, and phosphorus) off target, leaching them into the soil and groundwater or running off into surface waters.

Once in a creek, lake, river, or bay, this fertilizer intended to improve growth of turf or landscape plants instead fuels the growth of algae. In certain conditions this causes eutrophication, an overabundance of algae growth which gives water bodies a green, scum-covered appearance. As this plant material eventually breaks down, it uses up oxygen in the waters below, reducing the amount available for fish and other aquatic species.  These scenarios can lead to fish kills and reduced water quality.

A body of water receiving excess nutrients can turn green and unhealthy from too much algae growth. Photo Credit: UF IFAS FFL program

A body of water receiving excess nutrients can turn green and unhealthy from too much algae growth. Photo Credit: UF IFAS FFL program

The new legislation encourages professional lawn care staff to take a day-long course covering these concepts, and additional topics such as irrigation, pest management, and proper landscaping practices.  The course, offered online and in every UF IFAS Extension office, prepares the audience for the test and certification, and gives useful tips and information for their everyday work.

Several counties, most recently Escambia, have passed local ordinances echoing the requirement to have this license when seeking a business tax certification to operate a lawn care service (providing fertilizer) in the county.  In addition, local ordinances typically have a “prohibited application period,” which may involve a particular time of the year or weather condition. The ordinances also restrict blowing or sweeping lawn debris into storm drains, which can cause the same water quality problems as excess fertilizer.  Visit the GI-BMP website to learn more about the program, and if you, friends, or neighbors use a professional lawn care service to fertilize your lawn, be sure to ask for proof of their fertilizer license.






Author: Carrie Stevenson – ctsteven@ufl.edu

Coastal Sustainability Agent, Escambia County Extension

Carrie Stevenson

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2014/01/11/new-year-brings-new-fertilizer-regulations/

Fertilizer Explained


Image Credit UF IFAS Extension FYN Program

Fertilizer Spreader on lawn.  Image Credit UF IFAS Extension FYN Program




Fertilizers are manufactured from a wide variety of materials to supply plant nutrients.  Once these materials are mixed, it becomes difficult to distinguish the materials present.  In the past, a few unscrupulous manufacturers have taken advantage of this to increase their profit. To protect consumers and legitimate manufacturers from such practices, The Florida legislature enacted the first fertilizer law in 1889 and has amended it many times since enactment.  These laws regulate the manufacture and sale of fertilizer in the state.

The law requires that the manufacturer purchase and affix a label to each bag, package, container, or lot of fertilizer offered for sale in the state.  The law requires that each label show specific information about the analysis and composition of the mixture or material.

Image Credit UF IFAS

Image Credit UF IFAS

The key information comes in the guaranteed analysis section of the label.  It tells the home gardener the ratio by percentage of the primary plant nutrients. The number s are in the order of these primary nutrients; Nitrogen, Phosphorus and Potassium.  For example an 8-8-8 fertilizer would be eight percent nitrogen compound, eight percent phosphorus compound and eight percent potassium compound.


There’s some other information in this section of the label that may seem even more complicated but it’s also important.  The label explains how much chlorine the fertilizer can contain.  Chlorine can reduce the quality of some vegetable and flowers.


It informs the buyer what materials the primary plant nutrients are derived from.  This can assist in determining the quality of the fertilizer.


Probably the most difficult part of the label to read, certainly the hardest part to describe, is the information listed right after the total nitrogen figure in the guaranteed analysis section.  In addition the total amount of nitrogen, the label gives the amount of each of several types of nitrogen present in the fertilizer.  This information will seem confusing, but it also offers a glimpse into how the fertilizer will work in specific types of soil.


Terms such as nitrate nitrogen ammoniacal nitrogen, water-soluble organic nitrogen and/or urea nitrogen can be used by plants fairly quickly.  These nitrogen forms in fertilizer are great for a vegetable garden.  But nitrate and water-soluble organic nitrogen are rapidly leached out of the soil so they don’t last very long.  Ammoniacal and water insoluble nitrogen will stay longer in sandy soils.

Fertilizer with a high percentage of natural organic nitrogen is used by the plants slowly over a fairly long period of time.  This kind of slow release fertilizer would be good for lawns helping them stay green without causing spurts of extra fast growth.


This is a complicated subject, hard to fully explain in one article.  This is the take home message: almost any fertilizer purchased in Florida is a good one if it has the ingredients required for plant health and if the price is fair in terms of the total amount of plant nutrients it contains.


For more information on Florida fertilizer label contact your local UF IFAS Extension office or read this publication on the Florida Fertilizer Label.


Author: Roy Carter – rlcarter@ufl.edu

Roy Carter

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2013/11/04/fertilizer-explained/