Introduction History and Objectives Mode of nutrient release Classification of CRFs Advantages of CRFs Controlled release formulations Future needs

WHAT IS A CONTROL RELEASE FERTILIZER?

A synthetic fertilizer, usually encased in capsules, that releases its nutrients over a specific period of time much the same as a controlled-release drug releases its medicine

Controlled-release is one of the modern application that has enhanced how fertilizers are used both

commercially and by consumers. Fertilizer use efficiency can be increased by

modification of fertilizer products Chemical or Physical modificatios e.g coated

encapsulation CRFs will bring revolution in Agricultural

industry in near future

Controlled-Release-Fertilizer

CFRs began to be used in the 1930s

Reguler production started in 1936

CFRs became commercial in mid 1950s

Today used in USA and Japan

70 percent of conventionally applied fertilizer goes unutilized

Loss of nutrients due to volatilization and leaching

Fertilizer run-off in surface water leads to oxygen depletion

Negative environmental impacts Fertilizer waste through leaching

increases farm expenditures Less fertilizer use efficiency

Reduction of topical growth (flush growth) and clippings

Improved agronomic yields Improved rooting Improved cell wall strength Improved soil microorganism

health/populations Retention of desirable color

A Dry mixture of soluble fertilizer and thickener in a non-permeable envelope

Nutrient release in two phases i. water penetrates through opening to wt

the mixtureii. Nutrients release the device through

pore either by diffusion or connective flows

Water

Dissolved Urea

SolidUrea*

DissolvedUrea

Water

Dissolved Urea

CompleteRelease

*Or other nutrient

SolidUrea

H2O

H2O

SolidUrea

SolidUrea

SulfurCoating

H2O

DissolvedUrea

H2O

H2O+ S

Urea

NH4

H2O

Urease

Root

The three common timing formulas are used

1. Immediate release

2. Intermediate release

3. Long term release

SYSTEMATIC CLASSIFICATION

A. ORGANIC-N LOW-SOLUBILITY COMPOUNDS

Further divided into:I. Biologically decomposing

compounds e.g urea-formaldehydeII. Chemically decomposing compounds e.g isobutyledene-diurea

B. FERTILIZERS IN WHICH A PHYSICAL BARRIER CONTROLS THE RELEASE

Granules coated by non-permeable material

Material used can be hydrophobic or hydrophilic

C. INORGANIC LOW-SOLUBILITY COMPOUNDS

Here inorganic material is used for coating e.g:

Metal ammonium phosphates (Mg NH4PO4)

Acidulated phosphates rock

Fertilizer type (solubility, density) Thickener type Thickener concentration Size of device Temperature of soil Moisture in the soil

Fertilizer burn is not a problem with CRFs Less frequent application is required Easier and precise mechanical application Reduced capital and labor outlay Reduced nutrient loss by leaching and

run-off Reduced leaf burn

Flexibility of release periods from 40 to 360 days at 25º C

Reduced seed or seedling damage from high local concentrations of salts

Improved storage and handling properties of fertilizer materials

Product differentiation resulting in improved market potential.

MARKET PRICES FOR SLOW-RELEASE FERTILIZERS

Market prices of CRFs are high because of:

High prices of the ingredients used for encapsulated/coated products

Low production capacities significantly higher marketing and sales

expenses

MARKET PRICES FOR SLOW-RELEASE FERTILIZERS

In the United States encapsulated granular urea is sold at a price of US$ 600.00 to 1 000.00/ton

In Japan polyolefine-coated urea is sold at a price of 150 000 yen (= US$ 1 500.00 per t)

In Western Europe, the average user prices are US$ 700 to 1200 per t.

1.Urea-formaldehyde reaction products: also known as Nitroform, Ureaform, Methex. produced in 1936 and commercialized in 1955

Developed in 1960s and 1970s. Sulfur was used as coated material

because of its low cost and value as secondary nutrient

Manufactured inn 1970 in JapanPolymers are used for high-value applicationMost common three marketed products are Nutricote, Osmocote and Polyon

3. Polymer-coated fertilizer

Cotrolled Release Fertilizer

Fertilizer granules are heated and treated fatty acid and metal hydroxide

The two react to form a coating of the metal salt of a fatty acid, such as calcium stearate

Substrate coated components are nitrite, urea and triple super phosphate

These are hybrid products that utilize a primary coating of Sulfur and secondary polymer-coated fertilizer

These fertilizers were developed to deliver the nutrients at low cost

Very high costs of CRFs Lack of proper legislation in most parts

of the world to restrict the use of soluble fertilizers

Only about 0.15% of the total fertilizers consumption is such products

CRF may be inadequate sources of nutrients in situations with low ambient and soil temperatures

FUTURE NEEDS

Issues related to better NUE and a more environment friendly utilization of CRFs deserve greater attention and deeper insights, as listed below:

Improved utilization of advanced technologies to prepare CRFs.

Better understanding of the mechanisms controlling release rate and pattern

Better assessment of expected benefits to the environment by using CRFs

Development of soil degradable coatings

Improved quantification of economic advantages

1. Jacobs, D.F., Bose, R., Hasse, D.L. “Incorporating controlled release fertilizertechnology into outplanting”, in National Proceedings. Ogden, 2003, pp. 37-42.

2. Shavit, U., Shaviv, A., Shalit, G., Zaslazvsky, D.,J. Controlled Release, 1997.