Environmental Engineering Reference
In-Depth Information
PREMIUM
LAWN FERTILIZER
15-5-10
Guaranteed Analysis
Total Nitrogen (N)....................................... 15.0%
Ammoniacal Nitrogen................................. 2.9%
Urea Nitrogen............................................. 12.1%
Available Phosphate (P
2
O
5
)....................... 5%
Soluble Potash (K
2
O)................................. 10%
Sulphur (S) Total ........................................ 3%
Iron (Fe) Total ............................................
2%
KEEP OUT OF REACH OF CHILDREN
Fig. 5.2. A typical fertilizer label.
label (Fig. 5.2). Almost every country regulates by law the types of infor-
mation included on fertilizer labels, but all labels around the world would
contain information about the
fertilizer analysis
. The analysis represents the
percentage by weight of nitrogen (N), phosphate (P
2
O
5
) and potash (K
2
O)
in the fertilizer. These three numbers are always printed in the same order
and usually appear in a larger font than other information.
It is a common misconception that the three numbers represent
directly the percentages of nitrogen, phosphorus and potassium in the
fertilizer. In fact, only the first, the nitrogen number, represents the true
percentage of its element. Because the other two numbers represent
compounds of phosphorus and potassium, rather than the elements
themselves, the proportions of the elements are different. P
2
O
5
is only
44% phosphorus, and K
2
O is 83% potassium, e.g. a 15-15-15 fertilizer
contains not 15% nitrogen, 15% phosphorus and 15% potassium but
(15%
1.00
¼
) 15% nitrogen, (15%
0.44
¼
) 6.6% phosphorus and
(15%
) 12.45% potassium.
In most instances, however, fertilizer recommendations are already
expressed in terms of phosphate and potash, so the fertilizer user need
not make these calculations.
Most fertilizer labels also include other information, such as percent-
ages of specific nutrient carriers (nitrates, ammonia), chemical formulas,
type of release (slow, fast) and type of formulation (powder, granular,
liquid), etc.
In turf-grass situations, fertilizers, e.g. urea, ammonium nitrate,
super-phosphate, potash and ammonium sulphate, often contain only
one of the primary nutrients. Others, such as ammonium phosphate or
0.83
¼
