Fertilize to Save Money

Jason Kruse, Ph.D. University of Florida

[email protected]

Situation

• Prices for many products have risen steadily – Revenue increases have not kept pace

• Reduced budgets have resulted in staffing cuts

• Increasing demands placed on existing facilities – Events

– People

• Increasing expectations regarding aesthetics and play

Situation

• Expectations – Reduce/eliminate pesticides

– Reduce/eliminate fertilizers

– Organic???

• Goals – First and foremost – Safe,

playable surface!

– Make sure the turfgrass is not a point of discussion

Overview

• Role of nutrients in plant growth

• Fertilizer carriers - Nitrogen

• Cultural management practices

• Fertilizer price trends, predictions, purchasing recommendations

Role of Nutrients in Plants

Plant Nutrition

• An actively growing turfgrass plant is 75 - 85% water. – The remaining 15 - 25% of the plant’s weight is dry matter.

• Sixteen (16) elements are essential because a plant cannot successfully complete its life cycle without them.

• A major portion of the plant dry matter content consists of three (3) elements: – Carbon

– Hydrogen

– Oxygen

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Plant Nutrition

• Plants obtain carbon and oxygen from the atmosphere.

– Carbon dioxide (CO2), a gas, enters the leaves through the stomata.

– Water (H2O) taken in by the roots supplies hydrogen and oxygen.

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Essential Elements

• Macronutrients

– Nitrogen (N)

– Phosphorus (P)

– Potassium (K)

• Secondary

– Calcium (Ca)

– Magnesium (Mg)

– Sulfur (S)

• Micronutrients

– Iron (Fe)

– Manganese (Mn)

– Boron (B)

– Copper (Cu)

– Zinc (Zn)

– Molybdenum (Mo)

– Chlorine (Cl)

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Macronutrients – Nitrogen (N)

• Present in the greatest quantities: 2 – 5% in dry leaf tissue.

• Sufficiency Ranges: – Creeping Bentgrass = 4.5 – 6.0%

– Kentucky Bluegrass= 2.6 – 3.5%

– Ryegrass = 4.5 – 5.5%

– St. Augustinegrass = 2.0 – 3.0%

– Zoysiagrass = 2.0 – 3.0%

– Bermudagrass = 2.5 – 3.5%

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• Major impact on a number of factors:

– Effects on plant growth and metabolism, influencing grass response to a number of environmental stress conditions;

– Potential environmental implications;

– Must be routinely applied for a healthy, stress-tolerant turf;

– Accounts for the highest cost of a turfgrass fertilization program.

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• N Compounds in Plants - taken up as NO3-

(nitrate) and NH4+(ammonium).

– Amino acids – building blocks for proteins.

– Proteins

– Chlorophyll – photosynthesis

– Hormones - auxins, cytokinins, and ethylene.

– Nucleic Acids - DNA, RNA

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Nitrogen Deficiency

• The most common nutritional deficiency

• Growth slows dramatically

• Oldest leaves first become chlorotic (lose their dark green color, become yellowish), while newest leaves stay green.

– Nitrogen is transferred from the oldest, expendable leaves to the newest, most valuable leaves

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Macronutrients – Phosphorus (P)

• Present in the soil solution in very low concentrations and uptake is primarily as H2PO4

- (pH<7.0), HPO42- (pH>7.0), or certain

soluble organic phosphates.

• Phosphorus content of turfgrass shoot tissues may range from 0.10 to 1.00% by dry weight.

– Sufficiency range is 0.15 – 0.5%.

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• Uses in the plant: – Component of the energy molecules ATP and ADP.

• These compounds serve to store and transfer available energy within the plant.

– Structural constituent • Phospholipids • Phosphoproteins • Nucleic acids • Sugar phosphates • Nucleotides • Coenzymes

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• Visual Symptoms of deficiency

– Initially show up as reduced shoot growth and a dark green color.

• As P deficiency continues, lower leaves may turn reddish at the leaf tips and then progress down the blade.

• Stunted growth - caused by limited P for energy transformations.

• Element of impairment

18 Photo credit: Rosa Say


• Applications should be based on soil/tissue test results

Macronutrients – Potassium (K)

• Taken up and stored as the ionic (K+) form.

• Shoot tissue concentration of 1.0 to 3.0% by weight.

• Used in the plant: – Enzymes activator

– Most important solute in the vacuole • Osmoregulation = water regulation in plants

– Used in carbohydrate, amino acid, and protein synthesis

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• Visual symptoms of deficiency

– Interveinal yellowing of older leaves (lower), followed by dieback of leaf tip, scorching or firing of the margins, and total yellowing of the leaf blade including the veins.

– May appear weak or spindly.

– Under high evaporative demand, wilting and leaf firing may be accelerated as well as wear injury in high traffic areas.

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• Deficiencies result in:

– Increased respiration and transpiration

– Reduced environmental stress tolerance

– Increased disease incidence

– General reductions in growth

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Bottom Line

We must maximize our benefit of management practices to ensure a safe,

enjoyable facility for our customers

Nitrogen Fate

• What are some of the potential fates for N applied to a turf surface?

– Taken up by grass

– Microorganisms

– Denitrification

– Volatilization

– Leaching

Sources of Nitrogen

• Fertilizer

• Returned Clippings

• Organic Matter

• Lightning (precipitation)

Consider the Whole System!

• What can you change in your current system to further reduce N need?

– Mowing

– Irrigation

– Fertilization

– Equipment repair/replacement

– Inventory management

– Employees

Mowing/Maintenance

• Increase mowing height

– Increase root depth and photosynthetic capacity

• Reduce highly maintained areas

– Reducing fairway width/length to emphasize landing areas

– Reduce/Eliminate flower beds/ornamentals

– Fairways vs roughs

Seasonal Growth

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Irrigation

• Conduct irrigation audit

• Ensure application rate/amount does not exceed infiltration

• Match irrigation to weekly ET rates, accounting for rainfall received

– On-site weather station

– http://fawn.ifas.ufl.edu

• Irrigation + rainfall should not wet profile below rootzone, only refill it!

http://fawn.ifas.ufl.edu/

Soil Compaction

• Compacted soils

– Reduced pore space = reduced root growth = reduced N uptake

– Decreased infiltration increases risk of runoff

• Monitor compaction, vary method/depth of aerfication

Consider Your Fertilizer Material

Quickly Available N

• Very soluble

• Rapid response

• Short response

• Cheap

• Minimal temperature dependency

• High leaching potential

• Tendency to burn

Quickly Available N

• Ammonium nitrate 33-0-0

• Ammonium sulfate 21-0-0

• Ammonium phosphates

– mono-ammonium phosphate 11-48-0

– di-ammonium phosphate 20-50-0

• Potassium nitrate 13-0-44

• Urea (organic?) 46-0-0

Slow Release Nitrogen Sources

• Slow initial response

• Longer response than quick release

• Some, but not all, are dependent on temperature for N release

• Low burn potential

• Moderately expensive to expensive

• Less N leaching

Why Use Slow Release Fertilizers?

• More uniform growth response

• No growth surge

• Longer growth response

• Less chance of burn

• Less leaching of nitrate

• Labor saving

Uncoated Slow Release Fertilizers

• Urea formaldehyde (UF)

• Methylene urea (MU)

• Isobutylidene diurea (IBDU)

• Natural organics

Ureaform and Methylene Urea

• Very similar materials chemically

• Mostly granular, some liquids

• about 40% N, 70% WIN (28% N for liquids, all soluble)

• Formed by reacting urea and formaldehyde = chains of alternating C and N

• Main difference is chain length, and as a result, mineralization rate

Products

• Formolene 30-0-2

• FLUF 18-0-0

• Nitro 26 CRN 26-0-0

• Nitroform (Powder Blue, Blue Chip) 38-0-0

• CoRoN 28-0-0

– (25% of total N is urea)

Different Chain Lengths

Methylene Urea N-C-N

N-C-C-C

N-C-C-C-C

N-C-C-C-C-C-C-C

Urea Formaldehyde

N-C-N

N-C-C-C-C-C-C-C

N-C-C-C-C-C-C-C-C-C

N-C-C-C-C-C-C-C-C-C-C-C-C

N-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C

Ureaform and Methylene Urea

• Designed to release N for 8-12 weeks

• Contains unreacted urea, fast greening

• Requires soil microbial activity

– temperature sensitive, soil at 78o F is four times as active as soil at 42o F

– moisture sensitive

• Seasonal response

Nitroform

• Urea formaldehyde

• Insoluble organic

• 38% N; 65-71% WIN

• Biological N release

– Rate influenced by soil temperature

Nutralene

• Methylene urea

• 40% N; 38% WIN

• Biological N release

• More rapidly available than UF

• Not as adversely influenced by cool temperatures

IBDU

• Urea is reacted with isobutyraldehyde

• Only a single chemical product is formed, not a bunch of different molecules. 31% N, 90% WIN

• Different sized granules available

• N release depends on solubility and hydrolysis (IBDU molecule reacts with water and breaks apart), releasing urea.

• No free urea in IBDU, may need to add

IBDU

• Urea breaks down quickly to NH4

• IBDU is relatively insoluble, so only small amounts are available at any one time

• Release sensitive to soil moisture, less on dependant on temperature

• Release also depends on granule size and contact with soil. Smaller granules release N faster than larger granules

IBDU

• 31% N -90% WIN

• N released by hydrolysis

• Relatively unaffected by – Temperature

– pH

• Particle size important

• Excellent cool season response

Liquid Slow Release Fertilizers

• Chemistry similar to UF, MU

• Micro-suspension of MU (FLUF)

• CoRoN, N-Sure; 28%N, 7% as urea and 21% as short chain MU or small ring structure.

• Get quick and slow release

• Foliar application?

• Is slow release slow enough?

Liquid Slow Release Fertilizers

• Easily handled, applied

• Can be formulated with P and K

• Some have short storage life

• Require specialized delivery system

• Volume of liquid used in application is not enough to move the material down into the root system - must irrigate in

CoRon

• 28% N solution

• Polymethylene ureas and amine modified polymethylene ureas

• N release dependent upon microbial action

N-Sure

• 30% N

• Ring structured Triazones may contain methylene diurea

• N release by microbial action

• Response very similar to CoRon

Coated Slow Release Fertilizers

• SCU, sulfur coated urea

• Polymer coated urea

• Poly Coated Sulfur Coated Urea

Sulfur Coated Urea

• Molten sulfur (S) sprayed on urea in rotating drum, coated in wax sealant

• Experimentally produced in 1950’s, commercially in 1972

• N release determined by: – Coating thickness – Microbial degradation – Temperature – Moisture – Coating failure (cracks, abrasion)

Sulfur Coated Urea

• 32-38% N

• Release depends upon – Thickness of sulfur coating

– Biological activity

– Soil environment • Temperature

• pH

• Cool temperature response erratic

• Coating fragile, uneven

Polymer Coated Urea

• Solid urea or other nutrient core, coated with various polymers (“plastics”)

• Coatings are tough, resist damage, thin • Coating chemistry affects membrane

properties, release rate • Release is due to controlled diffusion, which is

fairly constant over time • Release depends on coat thickness, chemistry,

temperature, moisture

Polyon

• 40% N

• Polyurethane coated urea

• N release influenced by – Coating thickness

– Diffusion rate

– Soil temperature

• Good for both warm and cool season

• Coating is abrasion resistant

Poly-S

• Coated with sulfur and a polymer – Cheaper than regular

polymer coated fertilizers

• Release dependent on

– Temperature

– Soil moisture

Fertilizer Programs

• Minimum of 30-50% slowly available N is appropriate – Choose CRN source based on environmental

conditions, budget, level of traffic

• 4-10 lbs N/M annually, depending on level of use/traffic – Do not apply more than 1 lb soluble N/M at one time – Carefully consider use of coated products in high traffic

areas due to potential damage to coating

• Late fall application of IBDU has been shown to improve spring color

Consider site-specific management

PERCENT N RELEASED OVER TIME FOR SELECTED

CRN MATERIALS

7 14 28 42 56 84 112 140 1800

20

40

60

80

100

NITROFORM NUTRALENE MILORGANITE

POLYON SCU AN

Weeks of “Greening”

Nitrogen Source Application Rate Weeks Greening

Urea 1 4

Ammonium Sulfate 1 4

POLYON Regular 1.25 12

Nutralene 1.5 12

Nitroform 2 16

IBDU 1.5 12

Relative Product Price

Nitrogen Source Analysis $/ton $/lb N

Urea 46-0-0 700 0.76

Ammonium Sulfate 21 - 0 - 0 300 0.71

POLYON Regular 43 - 0 - 0 1,500 1.74

Nutralene 40 - 0 - 0 1,300 1.63

Nitroform 38 - 0 - 0 1,500 1.97

IBDU 31 - 0 - 0 1,500 2.42

Smart Purchases

Why is Nitrogen Fertilizer so High Priced?

• High prices have coincided with spikes in price of gas

• Fertilizer shipping costs are important

– U.S. imports more than 8 million metric tons of Nitrogen fertilizer annually

• Natural gas is used to manufacture N-fertilizers


N2 + CH4 + H2O

Nitrogen (atm) + Natural gas

Heat

Pressure

Anhydrous Ammonia

2NH3 + CO


+ Nitric acid

Anhydrous Ammonia

+ CO2

Urea Ammonium Nitrate

+ Sulfuric

Acid

Ammonium Sulfate

Price Volatility

• Price for fertilizers spiked in 2008/2009

– Spike in natural gas prices

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73

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79

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86

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91

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92

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95

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99

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U.S. Natural Gas Wellhead Price

Data 1: U.S. Natural Gas Wellhead Price(Dollars per Thousand Cubic Feet)N9190US3 U.S. Natural Gas Wellhead…

Price Volatility

• While prices have stabilized, futures prices trend upwards through 2016

• Price of natural gas is only a small piece of the picture…

Fertilizer Consumption

Millions of metric tons consumed annually

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5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

2002 2003 2004 2005 2006 2007 2008 2009 2010

US

China

Effect of Demand on Price

Volatile Prices

Volatile Prices

• Fertilizers

– As much as 85% of variable expenses

– Prices increased dramatically

• Nitrogen and Phosphorus – 300-400% increase from 2002-2008

– Within year price changes over past 3-4 seasons:

• +/- $100/ton for anhydrous ammonia seasonally

• +/- $500/ton for phosphorus seasonally

Source: Kenkel, P. and T. Kim. 2009. Optimal cash purchase strategies to reduce fertilizer price risk. Southern Agricultural Economics Association Annual Meeting, Atlanta, Georgia, January 31 – February 3, 2009.

Volatile Prices

• With so much within year variability, time of purchase is critical!

– Price is driven by world market

– Suppliers stockpile fertilizer for peak demand

– Dealers attempt to shift risk through advance purchase programs

– It is possible to save as much as 16% if purchased at correct time of the year

Volatile Prices

• Best time of year to purchase

– Urea: 1st or 2nd week in July

– Phosphorus: 1st week in November

• Highest prices

– Urea: March/April

– Phosphorus: March

Summary

• Proper nutrient management is essential • Careful management of cultural practices can

have significant impact on effectiveness of N applications

• Important to understand differences in fertilizer materials/use

• Slow release fertilizers have potential to save time/labor and wear on equipment

• Budget savings can be realized through scheduled purchases of fertilizer materials

Questions?

Jason Kruse, Ph.D. PO Box 110670

Gainesville, FL 32611

352-273-4569

[email protected]

Education

Fertilize to Save Money