Fertilizer Products
Primary, secondary and micronutrients and slow-release fertilizers
Primary Nutrients (nitrogen, phosphorus and potassium)
Since 1973/74, most of the increase in world nitrogen (N)
consumption is accounted for by urea and most of the phosphorus
(P) by diammonium phosphate. The potassium (K) market is
dominated by potassium chloride. The main factor influencing the
share of the different products is the nutrient concentration of
the product (annex 2)
- the higher the concentration the lower the costs of
distribution, storage and handling per unit of nutrient; these
are major elements of the total cost structure.
Urea, diammonium phosphate and potassium chloride each have a
high nutrient content.
Complex Fertilizers
Complex NPK fertilizers have the advantage of having all primary
nutrients in each granule.
Other nutrients can easily be incorporated if required.
A composition adapted to the crop helps to ensure balanced
fertilization.
Secondary Nutrients (Sulphur, magnesium and calcium)
Sulphur
(S) deficiencies occur with increasing frequency, due to
the large-scale use of fertilizers such as urea, ammonium
phosphate and potassium chloride, that do not contain sulphur.
While positively affecting the environment in several ways,
obligatory reductions in emissions of sulphur dioxide from the
burning of fossil fuels have also led to sulphur deficiencies in
soil.
The content of sulphur applied annually in various
fertilizer products, such as single superphosphate, ammonium
sulphate, potassium sulphate and NPK compound fertilizers is
estimated at ten million tonnes S.
Deficiencies of magnesium (Mg) are fairly common
especially on light, sandy soils.
Soil magnesium can be maintained through the application of
liming materials such as dolomitic limestone, kieserite
(magnesium sulphate) or other fertilizers containing magnesium.
Calcium (Ca)
is essential, but most soils contain sufficient supplies.
The application of calcic liming materials is often
required to reduce soil acidity, but calcium nutrient
deficiencies are infrequent.
Micronutrients
Micronutrients are needed in very small amounts (g/ha) compared
with macronutrients (kg/ha). However if there is a
micronutrient deficiency, crop yield and quality may be affected
as severely.
Micronutrients, whose content in plants is critical, are
the metallic elements iron, manganese, zinc, copper and
molybdenum and the non-metallic elements chlorine and boron.
In addition certain other nutrients, such as sodium,
silicon, cobalt and aluminium, may be beneficial for certain
plants.
Slow-release Fertilizers
Slow-release fertilizers
can be a more efficient source of nutrients than conventional
fertilizers, but their higher cost compared with conventional
fertilizers limits their use on field crops.
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Compound fertilizer
Material containing two or three of the primary nutrients,
N, P and K.
Complex fertilizer (mixed fertilizer - US)
Compound fertilizer in which the final product is made by
a process involving chemical reaction between the raw
materials and intermediates used. |
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