I've gotten asked countless times over the years for the weight of various amendments. It would have come in handy for myself years ago if this type of information had been made available. With that in mind, this chart, expresses the weight (in grams) of various amendments in different volumes, per cup. Keeping in mind, the brand or formulation of the material can change the weight, but this chart is certainly better than not having the information at all.
These weights can be converted to pounds (lbs), dividing them by 454 and then plugged into these equations, for figuring out NPK values in pounds per acre.
The first formula, will tell us how much of any given amendment to apply to achieve a desired nutrient level within a known planting area.
[(pounds per acre needed/square foot in an acre) x sq ft to be fertilized] / elemental percentage of fertilizer being applied
Example: A soil test says you need to apply 120 lbs per acre of P. You decide to use steamed bone meal. 2-14-0. Let's assume you have a 2' x 5' soil bed, so 10 sq ft.
[(120 lb/acre / 43,560 sq ft/acre) x 10 sq ft] / 0.14 = 0.1968 lbs of 2-14-0 steamed bone meal to provide 120 lbs of P to the 10 sq ft bed.
However, notice we also applied nitrogen in the bone meal. So that brings us to the second necessary formula, which is a simple 3 part process.
A. weight of fertilizer applied x percent of elemental nutrition
B. Square Foot per acre / square foot fertilized
C. A x B
To continue with the example above, in the process of applying the bone meal to get 120 lbs of P, we also added:
A. 0.1968 lbs bone meal x 0.02 (nitrogen) = 0.0004
B. 43,560 sq ft per acre / 10 sq ft = 4,356
C. 0.004 x 4,356 = 17.424 lbs of N applied
This should help anyone who is actually getting soil tests done and trying to adjust accordingly.
dank.Frank
These weights can be converted to pounds (lbs), dividing them by 454 and then plugged into these equations, for figuring out NPK values in pounds per acre.
The first formula, will tell us how much of any given amendment to apply to achieve a desired nutrient level within a known planting area.
[(pounds per acre needed/square foot in an acre) x sq ft to be fertilized] / elemental percentage of fertilizer being applied
Example: A soil test says you need to apply 120 lbs per acre of P. You decide to use steamed bone meal. 2-14-0. Let's assume you have a 2' x 5' soil bed, so 10 sq ft.
[(120 lb/acre / 43,560 sq ft/acre) x 10 sq ft] / 0.14 = 0.1968 lbs of 2-14-0 steamed bone meal to provide 120 lbs of P to the 10 sq ft bed.
However, notice we also applied nitrogen in the bone meal. So that brings us to the second necessary formula, which is a simple 3 part process.
A. weight of fertilizer applied x percent of elemental nutrition
B. Square Foot per acre / square foot fertilized
C. A x B
To continue with the example above, in the process of applying the bone meal to get 120 lbs of P, we also added:
A. 0.1968 lbs bone meal x 0.02 (nitrogen) = 0.0004
B. 43,560 sq ft per acre / 10 sq ft = 4,356
C. 0.004 x 4,356 = 17.424 lbs of N applied
This should help anyone who is actually getting soil tests done and trying to adjust accordingly.
dank.Frank
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