Introduction to Plant nutrients, Fertilizer specifications, Terminology and Definitions

1.1 Introduction

A fertilizer is a material that furnishes one or more of the chemical elements necessary for

the proper development and growth of plants. The most important fertilizers are fertilizer

products (also called chemical or mineral fertilizers), manures, and plant residues. A

fertilizer product is a material produced by industrial processes with the specific purpose of

being used as a fertilizer. Fertilizers are essential in today's agricultural system to replace

the elements extracted from the soil in the form of food and other agricultural products.

basic things about fertilizer

1.2 Plant Nutrients

Fertilizer- In the simplest terminology, a material, the main function of which is to provide
plant nutrients.
Soil Conditioner - Material added to soils, the main function of which is to improve their
physical and/ or chemical properties and/ or their biological activity.
Liming Material - An inorganic soil conditioner containing one or both of the elements
calcium and magnesium, generally in the form of an oxide, hydroxide, or carbonate,
principally intended to maintain or raise the pH of soil.
Straight Fertilizer: A qualification generally given to a nitrogenous, phosphatic, or
potassic fertilizer having a declarable content of only one of the primary plant nutrients, i.e.
nitrogen, phosphorus, or potassium.
Compound Fertilizer: A fertilizer that has a declarable content of at least two of the plant
nutrients nitrogen, phosphorus and potassium, obtained chemically or by blending or both.
Granular Fertilizer:- Solid material that is formed into particles of a predetermined mean
size.
Coated Fertilizer - Granular fertilizer that is covered with a thin of a different material in
order to improve the behavior and/ or modify the characteristics of the fertilizer.
Other related terms are:
Coated Slow-Release Fertilizer (AAPFCO)- A product containing sources of watersoluble nutrients, release of which in the soil is controlled by a coating applied to the

Chemical elements that are essential for the proper development and growth of plants are

typically referred to as plant nutrients. The list of plant nutrients recognized as being

necessary for plant growth has increased over the years and now totals sixteen,

1.2.1 Expression

Many countries express quantities or percentages of the primary nutrients in terms of

elemental nitrogen (N), phosphorus pen oxide (P2O5), and potassium oxide (K2O2).

Secondary nutrients and micronutrients usually are expressed on an elemental basis

although calcium and magnesium sometimes are expressed in the oxide form. However,

several countries express all plant nutrients on an elemental basis.

Classification of Elements Essential for Plant Growth

Major elements (Available from air or water)

Carbon

(Macronutrients)

Hydrogen

Oxygen

Primary nutrients Nitrogen

Phosphorus

Potassium

Secondary nutrients Calcium

Magnesium

Sulfur

Minor elements

Boron

(Micronutrients) Chlorine

Copper

Iron

Manganese

Molybdenum

Zinc

1.2.2 Fertilizer Grade

All fertilizer labels have three bold numbers. The first number is the amount of nitrogen (N),

the second number is the amount of phosphate (P2O5) and the third number is the amount

of potash (K2O). These three numbers represent the primary nutrients (nitrogen(N) -

phosphorus(P) - potassium(K)).

This label, known as the fertilizer grade, is a national standard. A bag of 10-10-10 fertilizer

contains 10 percent nitrogen, 10 percent phosphate and 10 percent potash.

Fertilizer grades are made by mixing two or more nutrient sources together to form a blend

that is why they are called "mixed fertilizers." Blends contain particles of more than one

color. Manufacturers produce different grades for the many types of plants.

You can also get fertilizers that contain only one of each of the primary nutrients. Nitrogen

sources include ammonium nitrate (33.5-0-0), urea nitrogen (46-0-0), sodium nitrate (16-0-

0) and liquid nitrogen (30-0-0). Phosphorus is provided as 0-46-0 and potash as 0-0-60 or

0-0-50.

1.2.3 Fertilizer Specifications

Specifications are the requirements with which a fertilizer should conform, as

agreed upon between buyer and seller. Fertilizer specifications meet differing requirements

depending on the use or intent of the specification information.

Specifications are normally used in the contract between the buyer and seller of a

fertilizer to ensure agreement on product characteristics or more often to define the product

in sufficient detail to effect the satisfaction of both buyer and seller.

1.3 Terminology and Definitions

The below specified definitions are those given by International Association for

Standardization (ISO) and Association of American Plant Food Control Officials

(AAPFCO)

Fertilizer Material- A fertilizer that meets any of the following conditions (AAPFCO):

1. Contains important quantities of no more than one of the primary plant nutrients

(nitrogen, phosphorus, or potassium).

2. Has 85% or more of its plant nutrient content present in the form of a single

chemical compound.

3. Is derived from a plant or animal residue or by product or natural material deposit

which has been processed in such a way that its content of plant nutrients has not

been materially changed except by purification and concentration.

Fertilizer- In the simplest terminology, a material, the main function of which is to provide
plant nutrients.
Soil Conditioner - Material added to soils, the main function of which is to improve their
physical and/ or chemical properties and/ or their biological activity.
Liming Material - An inorganic soil conditioner containing one or both of the elements
calcium and magnesium, generally in the form of an oxide, hydroxide, or carbonate,
principally intended to maintain or raise the pH of soil.
Straight Fertilizer: A qualification generally given to a nitrogenous, phosphatic, or
potassic fertilizer having a declarable content of only one of the primary plant nutrients, i.e.
nitrogen, phosphorus, or potassium.
Compound Fertilizer: A fertilizer that has a declarable content of at least two of the plant
nutrients nitrogen, phosphorus and potassium, obtained chemically or by blending or both.
Granular Fertilizer:- Solid material that is formed into particles of a predetermined mean
size.
Coated Fertilizer - Granular fertilizer that is covered with a thin of a different material in
order to improve the behavior and/ or modify the characteristics of the fertilizer.
Other related terms are:
Coated Slow-Release Fertilizer (AAPFCO)- A product containing sources of watersoluble nutrients, release of which in the soil is controlled by a coating applied to the fertilizer.

Polymer-Coated Fertilizer (AAPFCO)-A coated slow-release fertilizer consisting of

fertilizer particles coated with a polymer (plastic) resin. It is a source of slowly available

plant nutrients.

Controlled-Release Fertilizers- Fertilizers in which one or more of the nutrients have

limited solubility in the soil solution, so that they become available to thea growing plant

over a controlled period.

Nitrogen Stabilizer (AAPFCO) - A substance added to a fertilizer to extend the time that

the nitrogen component of the fertilizer remains in the soil in the ammonia cal form.

Liquid Fertilizer - A term used for fertilizers in suspension or solution and for liquefied

ammonia (ISO).