Nutrition of Horticultural Crops

Monica Ozores-Hampton and Francesco Di Gioia

University of Florida/IFAS/SWFREC

Spring 2015

Enhanced Efficiency Fertilizer (EEF)

Are products with characteristics that minimize the potential of

nutrient losses to the environment, as compared to “reference soluble”

fertilizers (AAPFCO, 2005)

Enhanced Efficiency Fertilizer

1. Slow release fertilizer (SRF)Products that release nutrients (in a plant available form), slowely

than “reference soluble” fertilizers, however the pattern of release is

not well controlled.

2. Controlled release fertilizer (CRF)Products that release nutrient slowely than “reference soluble”

fertilizers, in which the factors dominating the pattern of release are

well-known and controllable during CRF preparation.

3. Stabilized fertilizer (SF)Products amended with an additive that reduce the transformation

rate of fertilizer compounds, resulting in extended time of nutrient

availability in the soil.

HistoryIn the 1960s

To save labor and time, a single application of fertilizer that could release

fertilizer over time.

Mainly used in ornamental production and turf maintenance

In the 1980s

EEFs become tools to reduce the risk of nutrient losses while maintaining

productivity (environmental protection)

Currently

Althought the use of EEFs has almost doubled in the last 50 years, it

represent only 0.15 % of the global mineral market (Medina et al., 2009)

The agricultural sector consumes represent only 10% of the total EEFs use,

but demand has been increasing at annual rate of 10%.

Why to Use Enhanced Efficiency Fertilizer

Improve fertilizer use efficiency

Providing optimum levels of nutrients that match plants need

Matching the pattern of plant nutrient uptake with the kinetics of nutrient

release

Avoid split applications

Single basal application released at controlled rate over the season,

minimizing cost for fluel, labor and save time

Reduce nutrient losses and environmental impact of agriculture

Reduce losses of N by leaching, volatilization and denitrification

Improve vegetables quality

Reduce NO3-N concentration in leafy vegetables

Crop Requirements and N Availability

1. Slow Release Fertilizer (SRF)

SRFs contain N in a low-soluble, plant-

unavailable form that usually requires microbial

degradation to release plant-available N. Thus N

release is slower than conventional soluble

fertilizers, but the release rate, pattern, and

duration are not well-controlled.

Urea-formaldehyde (UF) 37 – 40 % NThese SRFs are condensation products of urea and formaldehyde in

a reaction that includes water, sulfuric acid, sodium hydroxide, and

surfactants.

+CH2N NH2

O

urea

CH H

O

formaldehyde

base

CH2N NH-CH2OH

OMonomethylol

Urea (MU)

CCH2OH-HN NH-CH2OH

ODimethylol

Urea (DMU)

+

Urea-formaldehyde Condensation Products

+CH2N NH2

O

urea

CH H

O

formaldehyde

acid+

CH2N NH

O

CHN NH2

O

CH2

CH2N NH

O

CHN NH

O

CH2

CHN NH2

O

CH2

Methylene – di – urea (MDU)

Di - methylene – tri – urea (DMTU)

+

TMTU ………

Characteristics Explanation

Total nitrogen The fertilizer grade typically 38% to 40% for UF and MU.

Cold water soluble nitrogen

(CWSN)

This nitrogen fertilizer fraction is soluble in 71.6 °F water and

is available to plants immediately or within a few weeks. The

CWSN fraction contains unreacted urea, methylene diurea, and

dimethylene triurea.

Cold water insoluble nitrogen

(CWIN)

This is the slowly available and unavailable nitrogen fertilizer

fraction that is not soluble in 71.6 °F water.

Hot water insoluble nitrogen

(HWIN)

This nitrogen fertilizer fraction is not soluble in 212 °F water,

and may be reported indirectly through back calculation using

the activity index. The HWIN may not be available to the

plants during the season applied.

Explanation of the fertilizer characteristics for urea formaldehyde

(UF) and methylene urea (MU).

Urea-formaldehyde Release:

pH, temperature, soil moisture, soil property

Microbial activity

Activity Index (AI): percentage of N insoluble in cold water that is

solubilized in hot water. Provide an estimate of the fraction of relatively

long-lasting release

AI=[(CWIN – HWIN) / CWIN] x 100

AI=[HWSN / (HWSN + HWIN)] x 100

Factors affecting N release:

Urea-aldehyde and Synthetic Nitrogen Compounds

Isobutyliden Diurea (IBDU) 31 % N

Reacting urea with

isobutyraldehyde

pH, Temperature

Soil moisture (hydrolysis), particle size

Factors affecting N release:

Mechanism of N release:

Hydrolysis

Urea-aldehyde and Synthetic Nitrogen Compounds

Crotonyliden Diurea (CDU) 32 % N

Reacting urea with

acetaldehyde in acid

conditions

pH, Temperature (microbial activity)

Soil moisture (hydrolysis), particle size

Factors affecting N release:

Mechanism of N release:

Combination of hydrolysis

and microbial activity

Controlled Release Fertilizer (CRF)

Fertilizer products that release nutrient slowely than “reference soluble”

fertilizers, in which the factors dominating the pattern of release are well-known and controllable during

CRF preparation

Sulfur Coated Urea (SCU) 31 – 38 % N

Coating preheated urea granules

with molten sulfur (156°C) and wax

Coating quality: thickness and uniformity

Soil moisture, temperature

Factors affecting N release:

Mechanism of N release:

Micro pores, holes, cracks

Microbial degradation

Sulfur Coated Urea (SCU)

Damaged coatings with cracks (catastrophic release)

Damaged coatings whose cracks are sealed with wax

Perfect and thick coatings (locked-off)

Water penetrates the coating through microscopic pores, dissolve

the nutrients and increases the osmotic pressure within the coated

core.

controlled release fertilizers

The osmotic pressure stretch the coating, enabling the

release of nutrient through pores and cracks

“Catastrophic or failure release”

Polymer Coated Urea (PCU)

Thermoplastic polymer-coated urea

Resin-coated urea

Alkyd resin (Osmocote)

Polyurethane (Polyon, Multicote, Plantacote)

Polyethylene (PE-impermeable) and Ehylene-vinyl-acetate (EVA - permeable)

Polyvinyl chloride (PVC)

Polyacrylamide (PA)

Natural rubber (NR) (=lattex)

Polylactic acid (PLA)

Polymer Coated Urea (PCU)

Mechanism of N release:

Diffusion Temperature

Factors affecting N release:

Coated membrane thickness

Water penetrates the coating through microscopic

pores, dissolve the nutrients and increases the osmotic

pressure within the coated core

The osmotic pressure stretch the coating, increasing

the micro-pores, enabling the release of nutrient

through them

“Leak-type release”

Polymer Coated Urea (PCU)

Coating thickness effect on N release

Polymer Coated Urea (PCU)

Temperature effect on N release

Polymer Coated Urea (PCU)

Release from a single coated urea:

Diffusion vs. Failure

Time

Rele

ase

Manufacturerz Trade name Type of CRF Coating description Formulation examples

Agrium, Inc. ESN®

Polymer-coated

urea

Flexible micro-thin polymer

coating

ESN® (44-0-0)

Agrium, Inc. Polyon®

Polymer-coated Ultra-thin ployurethane coating

that uses patented “Reactive

Layers Coating”

Polyon® NPK (20-6-13), Polyon

® (41-0-0)

Agrium, Inc. Duration® Polymer-coated Micro-thin polymer membrane Duration® (44-0-0), Duration® (19-6-13)

Agrium, Inc. XCU®

Polymer/sulfur-

coated urea

Urea coated first with polymer

and then sulfur and wax

XCU® (43-0-0)

Chisso-Asahi

Fertilizer Co.

Nutricote® Resin-coated Resin coating with a special

chemical release agent

Nutricote® (28-0-0)

Chisso-Asahi

Fertilizer Co.

Meister® Resin-coated Granular urea coated with a

polymer composition of natural

products, resin and additives

Meister®

(21-7-4), Meister®

(19-5-14)

Everris, Inc. Osmocote® Resin-coated Alkyd-resin coating made in a

batch process from vegetable oil

and resin

Osmocote® Classic (8-16-12), Osmocote

®

Plus (16-9-12), Osmocote® Pro (17-11-

10+2MgO+TE)

Everris, Inc. Poly-S®

Sulfur/polymer-

coated urea

Urea coated first with sulfur and

then polymer

Poly-S® (37-0-0)

Everris, Inc. Agrocote®

Sulfur/polymer,

and resin-coated

Either 100% N or K potassium

fully coated with polymer/sulfur

and resin coatings

Agrocote®

(39-0-0+11%S), Agrocote®

(0-0-

42+14%S),

Haifa Group Multicote® Resin-coated Water-soluble nutrients

encapsulated in a polymeric shell

Multicote® Agri 4 (34-0-7), Multicote

® Agri

6 (22-8-13) and (34-0-7), Multicote®

Agri 8

(34-0-7)

J.R. Simplot Florikote® Polymer-coated Dual layer technology coats the

fertilizer with a smooth exterior

coating with no breaks

Florikote®

(12-0-40), Florikote® (19-6-13),

Florikote® (40-0-0)

Manufacturer, trade name, control release fertilizer (CRF) type, coating

description, and formulation of different CRFs.

Stabilized Fertilizer (SF)

Fertilizer products amended with an additive reducing the transformation

rate of fertilizer compounds, resulting in extended time of availability in the soil

Nitrification Inhibitor

Stabilized fertilizers

Nitrification Inhibitor

Stabilized fertilizers

Nitrification Inhibitor

Chemical name Common or trade name Manufacturer

2-chloro-6-(trichloromethyl)-pyridine Nitrapyrin, N-serve Dow Chemical Co.

5-Ethoxy-3-trichloromethyl-1,2,4-thiadiazol Dwell, Terrazole, Etradiazo Uniroyal Chemical

Dicyandiamide DCD SKW Trostberg AG

3,4-Dimethylpyrazole phosphate DMPP (ENTEC) BASF AG

2-Amino-4chloro-6-methyl-pyrimidine AM Mitsui Toatsu Co.

2-Mercapto-benzothiazole MBT Onodo Chemical Ind.

2-Sulfanilamidothiazole ST Mitsui Toatsu Co.

Thiourea TU Nitto Ryuso

Stabilized fertilizers

Nitrification Inhibitor

Inhibitor properties:

- water solubility

- volatility

soil chemical and physical properties:

- pH

- organic matter

- soil texture

Factors influencing the mobility, persistence and effectiveness of NIs:

soil biological properties:

- Genetic variability in Nitrosomonas strains

Abiotic factors:

- Temperature

Nitrification Inhibitor

Factors influencing the mobility, persistence and effectiveness of NIs:

NIs are more effective in:

- Light-textured soils,

- Low organic matter soils,

- Low temperature (≤ 5°C)

NIs are less effective in:

- Heavy-textured soils,

- High organic matter soils,

- High temperature

Stabilized fertilizers

Urease Inhibitor

NH3 + H+

CO(NH2)2 + H+ + H2O 2NH4+ + HCO3

-urease

Urease InhibitorA large number of compounds with differing characteristics have been

tested for their ability to inhibit urease activity

Organic and inorganic compounds inhibit the enzyme:

- Reacting with active sites on the enzyme

- Interacting with a key functional group in the molecule

- Changing the conformation of the active site

- Complexing nickel in the active site (e.g. hydroxamates)

- Being structural analogues of urea and competing for the enzyme

(e.g. thiourea, methylurea, phosphoryl di- and triamides)

Urease Inhibitor

The most effective compounds for the inhibition of urease activity

appear to be the phosphoryl amides:

- N-(n-butyl) phosphoric triamide

- N-(butyl) cyclohexylphosphoric triamide

Urease Inhibitor

The unique urease inhibitor commercially available is:

N-(n-butyl) thiophosphoric triamide (NBPT - AgrotaiN)

Urease InhibitorUrease inhibitors are expected to be most beneficial on soils when:

(i) Loss of NH3 from urea fertilizers is high

(ii) Incorporation of urea is difficult

(iii) There is little opportunity for the urea to move into the soil

with infiltrating water

(iv) The soil surface has a high urease activity due to lack

of cultivation or the accumulation of organic matter.

Fertilizer Price ($/ton)

Soluble urea 380 to 560

Soluble potassium nitrate 1,150 to 1,500

Methylene urea 750 to 1,000

Urea-formaldehyde 1,100 to 1,300

IBDU® 1,400 to 1,600

Controlled-release urea (sulfur coated) 775 to 875

Controlled-release urea (polymer sulfur coated) 500 to 1,000

Controlled-release urea (polymer) 700 to 1,500

Controlled release NPK (polymer)y 810 to 2,000

Urease inhibitor 20 to 30x

Nitrification inhibitor 4 to 8x

xThese products are marketed in 2.5 gallon containers. The listed price is additional to the price of the soluble fertilizer and does not reflect

additional application costs that may be associated.

Prices of enhanced-efficiency fertilizers for use in vegetable production

Enhanced Efficiency Fertilizer

EEFs as BMP tool

Are recognized as one of the few BMPs that have a

direct impact on off-site nutrient movement and water

quality.

EEFs crop yield improvement

Can certainly minimize the losses of nutrient in the

environment if opportunely applied, however, their

effectiveness in increasing crop yield must be evaluate

case by case. Several studies report low or absent yield

increase.

Enhanced Efficiency FertilizerEEFs Economical benefits

Use in agriculture must be supported from an economical

convenience, currently the fertilizer prices are very

instable, however EEFs are still more expensive

compared to soluble fertilizers, therefore, their higher

cost must be offset by reducing application cost and/or

providing higher production

EEFs classification and regulation

An approved methodology is needed to estimate nutrient

release properties from a broad range of materials

Commercial label regulation is not complete

Carson, L., M. Ozores-Hampton, K. Morgan, and J. Sartain. 2014. Prediction of controlled-release fertilizer nitrogen

release using the pouch field and accelerated temperature controlled incubation methods in Florida sandy soils.

HortScience 49:1575-1581.

Carson, L., M. Ozores-Hampton, K. Morgan, and J. Sartain. 2014. Nitrogen release properties of controlled-release

fertilizers in tomato production of South Florida. HortScience 49:1568-1574.

Carson, L., M. Ozores-Hampton, K. Morgan, and S. Sargent. 2014. Effects of controlled-release fertilizer nitrogen rate,

placement, source, and release duration on tomato grown with seepage irrigation. HortScience 49:798-806.

Carson, L., M. Ozores-Hampton, K. Morgan, and S. Sargent. 2014. Effect of controlled-release and soluble fertilizer on

tomato production and postharvest quality in seepage irrigation. HortScience 49:89-95.

Carson, L. and M. Ozores-Hampton. 2014. Description of enhanced-efficiency fertilizers for use in vegetable production.

EDIS, HS1247, http://edis.ifas.ufl.edu/pdffiles/HS/HS124700.pdf

Carson, L. and M. Ozores-Hampton. 2013. Factors affecting nutrient availability, placement, rate and application timing

of controlled-release fertilizers for Florida vegetable production using seepage irrigation. HortTechnology 23:553-562.

Carson, L., M. Ozores-Hampton, and K. T. Morgan. 2013. Nitrogen release from controlled-release fertilizers in seepage-

irrigated tomato production in south Florida. Proc. Fla. State Hort. Soc. 126:131-135.

http://fshs8813.wpengine.com/proceedings-o/2013-vol-126/2013-toc.pdf

Carson, L. and M. Ozores-Hampton. 2012. Methods for determining nitrogen release from controlled-release fertilizers

used for vegetable production. HortTechnology 22:20-24.

Carson, L. and M. Ozores-Hampton. 2012. Effect of controlled-release soluble fertilizer on tomato grown with seepage

irrigation in Florida sandy soils. Proc. Fla. State Hort. Soc.

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Literature Review