Hey people,
this has been bothering me very much lately.
I look at analysis tables of nutrients, say Jack’s Professional, Yara or Haifa. The nutrient compositions are expressed in 3 numbers. For example 20-20-20. We call this N-P-K composition or N-P-K ratios.
These numbers refer to percentage of total weight.
My BIG question is: Why is percentage of P2O5 and K2O given rather than that of elemental P and elemental K??? After all percentage of elemental N is given too!
P2O5 consists of 44% elemental Phosphorus.
K20 is 83% elemental Potassium.
Wouldn’t that make Jack’s 20-20-20 general purpose a 20 - 8.8 - 16.6?
20-20-20 seems like a 1-1-1 ratio but isn’t it actually a 2.3 - 1 - 1.9 ??
After all, when we talk about concentration of nutrient solution we use PPMs of elemental forms of P and K and everything else. We wouldn’t talk about so and so much PPM of P2O5 or K2O.
Please somebody help me get a grasp of this. Would be much appreciated!
G
