Agriculture Reference
In-Depth Information
The total weight is 94. Divide the weight of K by the total weight
78 / 94 = 0.829 or 83% actual elemental K.
If the soil test report you are working from lists Phosphorus as P
2
O
5
, you
should first convert P
2
O
5
to elemental Phosphorus by multiplying P
2
O
5
x
0.44.
Calculating Phosphorus
Figuring out the amount of Phosphorus we need is simple and straightforward.
Here is theAnion section from the soil report:
Anions
Sulfur S (parts per million ppm)
20
Phosphorus P ppm
[227 ppm P
2
O
5
]
100
Our Potassium (actual K) is 178 ppm, so we simply subtract the amount of actual P
shown on the soil report from the amount of total K in our Ideal Soil
178 ppm - 100 ppm = 78 ppm
We will need to add 78 ppm of elemental Phosphorus to the soil
.
Sulfur S
Here is the Sulfur part of the Ideal Soil chart:
Sulfur S - - min 50 ppm
1/2 x Ideal K up to 300 ppm
Need for Sulfur amino acids
Conserves soil N and Carbon.
Here is the Sulfur reading from our soil report:
Sulfur S (parts per million)
20
We calculated above that we wish to end up with 178 ppm of Potassium K, and the
Ideal Soil chart tells us that we want ½ as much Sulfur as “Ideal” K (K=4% of CEC),
so we divide the K amount by 2:
178 / 2 = 89 ppm S would be our desired amount.
Subtract our existing Sulfur level of 20 ppm:
89 - 20 = 69 ppm
