ISO 14000 AND ISO 18000/DNOS 3233 Page 1

INTRODUCTION

What is a fertilizer?

A fertilizer is any material, organic or inorganic, natural or synthetic, that supplies plants with

the necessary nutrients for plant growth and optimum yield. Organic fertilizers are natural

materials of either plant or animal origin, including livestock manure, green manures, crop

residues, household waste, compost, and woodland litter. Inorganic (or mineral) fertilizers are

fertilizers mined from mineral deposits with little processing (e.g., lime, potash, or phosphate

rock), or industrially manufactured through chemical processes (e.g., urea). Inorganic fertilizers

vary in appearance depending on the process of manufacture. The particles can be of many

different sizes and shapes (crystals, pellets, granules, or dust) and the fertilizer grades can

include straight fertilizers (containing one nutrient element only), compound fertilizers

(containing two or more nutrients usually combined in a homogeneous mixture by chemical

interaction) and fertilizer blends (formed by physically blending mineral fertilizers to obtain

desired nutrient ratios).

Inorganic Commercial Fertilizer

Fertilizers are broadly divided into organic fertilizers (composed of organic plant or animal

matter), or inorganic or commercial fertilizers. Plants can only absorb their required nutrients if

they are present in easily dissolved chemical compounds. Both organic and inorganic fertilizers

provide the same needed chemical compounds. Organic fertilizers provided other macro and

micro plant nutrients and are released as the organic matter decays—this may take months or

years. Organic fertilizers nearly always have much lower concentrations of plant nutrients and

have the usual problems of economical collection, treatment, transportation and distribution.

Inorganic fertilizers nearly always are readily dissolved and unless added have few other macro

and micro plant nutrients. Nearly all nitrogen that plants use is in the form of NH3 or

NO3compounds. The usable phosphorus compounds are usually in the form of phosphoric acid

(H3PO4) and the potassium (K) is typically in the form of potassium chloride (KCl). In organic

fertilizers nitrogen, phosphorus and potassium compounds are released from the complex organic

ISO 14000 AND ISO 18000/DNOS 3233 Page 2

compounds as the animal or plant matter decays. In commercial fertilizers the same required

compounds are available in easily dissolved compounds that require no decay—they can be used

almost immediately after water is applied. Inorganic fertilizers are usually much more

concentrated with up to 64% (18-46-0) of their weight being a given plant nutrient, compared to

organic fertilizers that only provide 0.4% or less of their weight as a given plant nutrient

WORK PROCESS CHOSEN

The industrial production of fertilisers may involve several processes.

1. NITROGEN FERTILISERS

Making nitrogen fertilisers involves producing ammonia, which is then reacted withoxygen to

produce nitric acid. Nitric acid is used to acidify phosphate rock to produce nitrogen fertilisers.

The flow diagram below illustrates the processes that are involved. Each of these steps will be

examined in more detail.

Figure 1: Flow diagram showing steps in

the production of nitrogen fertilisers

1. THE HABER PROCESS

ISO 14000 AND ISO 18000/DNOS 3233 Page 3

The Haber process involves the reaction of nitrogen and hydrogen to produce

ammonia. Nitrogen is produced through the fractional distillation of air. Fractional distillation is

the separation of a mixture (remember that air is a mixture of different gases) into its component

parts through various methods. Hydrogen can be produced through steam reforming. In this

process, a hydrocarbon such as methane reacts with water to form carbon monoxide and

hydrogen according to the following equation:

Nitrogen and hydrogen are then used in the Haber process. The equation for the Haber process

is:

(The reaction takes place in the presence of an iron ( ) catalyst under conditions of 200

atmospheres (atm) and 450–500 ℃)

2. THE OSTWALD PROCESS

The Ostwald process is used to produce nitric acid from ammonia. Nitric acid can then be used in

reactions that produce fertilisers. Ammonia is converted to nitric acid in two stages. First, it is

oxidised by heating with oxygen in the presence of a platinum catalyst to form nitric oxide and

water. This step is strongly exothermic, making it a useful heat source.

Stage two, which combines two reaction steps, is carried out in the presence of water. Initially

nitric oxide is oxidised again to yield nitrogen dioxide:

ISO 14000 AND ISO 18000/DNOS 3233 Page 4

This gas is then absorbed by the water to produce nitric acid. Nitric oxide is also a product of this

reaction. The nitric oxide ( ) is recycled, and the acid is concentrated to the required strength.

3. THE NITROPHOSPHATE PROCESS

The nitrophosphate process involves acidifying phosphate rock with nitric acid to produce a

mixture of phosphoric acid and calcium nitrate:

When calcium nitrate and phosphoric acid react with ammonia, a compound fertiliser is

produced.

If potassium chloride or potassium sulphate is added, the result will be  fertiliser.

4. OTHER NITROGEN FERTILISERS

Urea ( ) is a nitrogen-containing chemical product which is

produced on a large scale worldwide. Urea has the highest nitrogen

content of all solid nitrogeneous fertilisers in common use (46,4%) and is

produced by reacting ammonia with carbon dioxide.

Two reactions are involved in producing urea:

1.

2.

ISO 14000 AND ISO 18000/DNOS 3233 Page 5

Other common fertilisers are ammonium nitrate and ammonium sulphate.

Ammonium nitrate is formed by reacting ammonia with nitric acid.

Ammonium sulphate is formed by reacting ammonia with sulphuric acid.

2. PHOSPHATE FERTILISERS

The production of phosphate fertilisers also involves a number of processes. The first is the

production of sulphuric acid through the contact process. Sulphuric acid is then used in a reaction

that produces phosphoric acid. Phosphoric acid can then be reacted with phosphate rock to

produce triple superphosphates.

1. The production of sulfuric acid

Sulfuric acid is produced from sulphur, oxygen and water through the contact process. In the first

step, sulphur is burned to produce sulphur dioxide.

This is then oxidised to sulphur trioxide using oxygen in the presence of a vanadium(V) oxide

catalyst.

Finally the sulphur trioxide is treated with water to produce 98-99% sulfuric acid.

ISO 14000 AND ISO 18000/DNOS 3233 Page 6

2. The production of phosphoric acid

The next step in the production of phosphate fertilizer is the reaction of sulfuric acid with

phosphate rock to produce phosphoric acid ( ). In this example, the phosphate rock is

fluoropatite ( )

3. The production of phosphates and superphosphates

When concentrated phosphoric acid reacts with ground phosphate rock, triple superphosphate is

produced.

3. POTASSIUM

Potassium is obtained from potash, an impure form of potassium carbonate ( ). Other

potassium salts (e.g.   and  ) are also sometimes included in fertilisers.

IMPACT TO THE ENVIRONMENT

1. WATER QUALITY

a. Eutrophication

Eutrophication is the enrichment of an ecosystem with chemical nutrients, normally by

compounds that contain nitrogen or phosphorus. Eutrophication is considered a form of pollution

because it promotes plant growth, favouring certain species over others. In aquatic environments,

the rapid growth of certain types of plants can disrupt the normal functioning of an ecosystem,

causing a variety of problems. Human society is impacted as well because eutrophication can

decrease the resource value of rivers, lakes, and estuaries making recreational activities less

enjoyable. Health-related problems can also occur if eutrophic conditions interfere with the

treatment of drinking water.

ISO 14000 AND ISO 18000/DNOS 3233 Page 7

b. Blue baby syndrome

High application rates of inorganic nitrogen fertilizers in order to maximize crop yields,

combined with the high solubilities of these fertilizers leads to increased runoff into surface

water as well as leaching into groundwater. The use of ammonium nitrate in inorganic fertilizers

is particularly damaging, as plants absorb ammonium ions preferentially over nitrate ions, while

excess nitrate ions which are not absorbed dissolve (by rain or irrigation) into runoff or

groundwater.

Nitrate levels above 10 mg/L (10 ppm) in groundwater can cause 'blue baby syndrome'

(acquired methemoglobinemia), leading to hypoxia (which can lead to coma and death if not

treated).

2. SOIL

a. Soil acidification

Nitrogen-containing inorganic and organic fertilizers can cause soil acidification when

added. This may lead to decreases in nutrient availability which may be offset by liming.

b. Persistent organic pollutants

Toxic persistent organic pollutants ("POPs"), such as Dioxins, polychlorinated dibenzo-p-

dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) have been detected in agricultural

fertilizers and soil amendments

c. Heavy metal accumulation

The concentration of up to 100 mg/kg of cadmium in phosphate minerals increases the

contamination of soil with cadmium.

Steel industry wastes, recycled into fertilizers for their high levels of zinc (essential to plant

growth), wastes can include the following toxic metals: lead , cadmium,arsenic, chromium, and

nickel. The most common toxic elements in this type of fertilizer are mercury, lead, and arsenic. 

ISO 14000 AND ISO 18000/DNOS 3233 Page 8

d. Radioactive element accumulation

Uranium is another example of a contaminant often found in phosphate fertilizers (at levels from

7 to 100 pCi/g). Eventually these heavy metals can build up to unacceptable levels and build up

in vegetable produce. Average annual intake of uranium by adults is estimated to be about

0.5 mg (500 μg) from ingestion of food and water and 0.6 μg from breathing air.

Also, highly radioactive Polonium-210 contained in phosphate fertilizers is absorbed by the roots

of plants and stored in its tissues; tobacco derived from plants fertilized by rock phosphates

contains Polonium-210 which emits alpha radiation estimated to cause about 11,700 lung cancer

deaths each year worldwide.

For these reasons, it is recommended that nutrient budgeting, through careful observation and

monitoring of crops, take place to mitigate the effects of excess fertilizer application.

3. ATMOSPHERE

Methane emissions from crop fields (notably rice paddy fields) are increased by the application

of ammonium-based fertilizers; these emissions contribute greatly to global climate change as

methane is a potent greenhouse gas.

Through the increasing use of nitrogen fertilizer, which is added at a rate of 1 billion tons per

year presently to the already existing amount of reactive nitrogen, nitrous oxide (N2O) has

become the third most important greenhouse gas after carbon dioxide and methane. It has a

global warming potential 296 times larger than an equal mass of carbon dioxide and it also

contributes to stratospheric ozone depletion.

The use of fertilizers on a global scale emits significant quantities of greenhouse gas into the

atmosphere (citation needed). Emissions come about through the use of:

animal manures and urea, which release methane, nitrous oxide, ammonia, and carbon

dioxide in varying quantities depending on their form (solid or liquid) and management

(collection, storage, spreading)

ISO 14000 AND ISO 18000/DNOS 3233 Page 9

fertilizers that use nitric acid or ammonium bicarbonate, the production and application of

which results in emissions of nitrogen oxides, nitrous oxide, ammonia and carbon

dioxide into the atmosphere.

By changing processes and procedures, it is possible to mitigate some, but not all, of these

effects on anthropogenic climate change

4. OTHER PROBLEMS

Increased pest fitness

Excessive nitrogen fertilizer applications can also lead to pest problems by increasing the birth

rate, longevity and overall fitness of certain agricultural pests, such as aphids (plant lice).

RECOMMENDATION

 Inorganic fertilisers can be formulated to apply the appropriate ratio of nutrients to meet plant

growth requirements. 

CONCLUSION

I have come to the realization that fertilizer has a negative impact on the environment whether it

is organic or not. Synthetic fertilizers have more chemicals in them and I believe that they impact

the environment to a harsher extent than organic fertilizers. I have started to question the

relationship between inorganic fertilizers and pesticide use. I assume that people who use

synthetic fertilizers are more likely to use pesticides and I am curious to find out whether this is

true. I am also interested in learning about the impact that pesticides have on the environment

and on the foods that they are used on. In general this research has increased my curiosity about

horticulture and agricultural practices and has reaffirmed my belief that everything is

interconnected in the environment. I have come to the conclusion that if your soil requires

nutritional intervention it is best to go as organic as possible.

ISO 14000 AND ISO 18000/DNOS 3233 Page 10