Update: I have discontinued fertilizing for about two weeks now since plants are beginning to bud and flower. I have noticed a big difference in growth between fertilized and unfertilized plants. You can see the difference from this photo of my Yellow Orinoco patch.
For the most part: the plants to the left were fertilized, whereas the ones to the right were not. The first row across had a mild dosage. I will still need at least another season to collect more data - I can see this being an ongoing project. There are many variables to consider
since each grower has different soil:
- pH
- amounts of macronutrients N-P-K (nitrogen, phosphorus, potassium)
- levels of micronutrients (boron, iron, manganese, zinc, etc.)
- and several other things...
Because of this, I have come to the conclusion that there is no single formula that could be used as an all-purpose "tobacco specific" fertilizer. However, I am now focusing on producing a nitrogen-rich formula (with a neutral pH and no chloride) to promote leaf growth. I will also exclude the micronutrients - I feel that these can be supplemented separately if soil tests indicate a deficiency.
The only downside of using ultra-high grade compounds in quantities necessary to fertilize is cost. In fact, this has become the limiting factor in my project. It is not economically feasible to pay $800 a year to fertilize a hundred plants! Oh well, I'll keep you guys posted when I learn more.