Crush Strength
Crushing strength is the minimum pressure needed to crush individual
particles. Determining the crushing strength, or hardness, will help
determine handling and storage requirements of a chosen granular product.1
Measure crushing strength by applying pressure to individual
granules. A simple finger test can be used in the field.
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Granule crushed between thumb and forefinger is “soft”.
-
Granule crushed between forefinger and a hard surface is “medium
hard”.
-
Granule not crushed between forefinger and hard surface is “hard”.
Crushing Strengths of Typical Fertilizers
|
Fertilizer Type2
|
Grade
|
Crush Strength
|
|
Prilled Urea
|
46-0-0
|
0.8-1.2
|
|
Granule Urea
|
46-0-0
|
1.5-3.5
|
|
Granule Ammonium Sulfate
|
21-0-0
|
1.5-2.5
|
|
Prilled Ammonium Nitrate
|
34-0-0
|
1.2-1.7
|
|
Granule Diammonium Phosphate
|
18-46-0
|
3.0-5.0
|
|
Granule Monoammonium Phosphate
|
11-55-0
|
2.0-3.0
|
|
Granule Triple Superphosphate
|
0-46-0
|
4.5-8.0
|
|
Prilled Potassium Nitrate
|
13-0-44
|
1.5-2.0
|
|
Granule Potassium Chloride
|
0-0-60
|
3.0-5.0
|
|
Granule Potassium Sulfate
|
0-0-50
|
3.0-4.0
|
Any granule with a less than three (<3) crush strength should
not be broadcast with spinner speeds over 700 rpm. Verify granules
are not pulverized before increasing speed.
|
1 T.P. Hignett. Fertilizer Manual. (Netherlands:
Kluwer Academic Publications and Springer Science+Business, 1998),
p. 478-479 with kind permission from Springe Science+Business Media
B.V.
2 Hignett,
Fertilizer Manual, p.481, table18.6.
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CS12167,00002B3-19-20130502
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