Environmental Engineering Reference
In-Depth Information
potassium nitrate, may contain two. Still others are blends of several
nutrient carriers. Fertilizers that contain all three primary nutrients -
nitrogen, phosphorus and potassium - are called
complete fertilizers
.
Other classifications are 'low analysis' fertilizers, in which the three
primary nutrients make up less than 30% of the total (e.g. sewage sludge
and most organic fertilizers) and 'high analysis' fertilizers, in which the
combined total is greater than 30% (e.g. most inorganic fertilizers).
Fertilizer Sources
Even though 16 different mineral elements are essential for the growth of
turf-grass, nitrogen is by far the most important. It has a dramatic impact
on turf-grass colour, growth, density, tolerance to stress and recuperative
ability.
A wide selection of nitrogen sources is available for use in turf-grass
situations. Some are the same for turf and agronomic crops, whereas
others are unique to turf-grass. An understanding of the various nitrogen
sources is critical in determining the best nitrogen source for a particular
turf-grass situation.
In general, nitrogen sources can be separated into the groups pre-
sented in Fig. 5.3. Many of them are relatively easy to manufacture and
therefore inexpensive. Figure 5.4 presents examples of chemical synthesis
of several popular nitrogen fertilizers.
Inorganic nitrogen carriers
Ammonium sulphate, ammonium nitrate, calcium nitrate and potassium
nitrate are common inorganic fertilizers. Once they are applied to the soil,
Inorganic
Organic
[NH
4
NO
3
]
[(NH
4)2
SO
4
]
[NH
4
H
2
PO
4
]
Synthetic organic
Natural organic
compost
sewage
manure
Fast release
Slow release
(urea)
Chemically reacted
Encapsulated
sulphur-coated
ureas, polymer-
coated ureas
methylene ureas, urea
formaldehyde, triazone
Fig. 5.3. Nitrogen sources used in turf-grass management.
