The construction is X is important to Y where X and Y are noun-phrases of some sort.
The key to the safe is important to the security of your money.
X: The key to the safe
Y: The security of your money
learn about what will help farmers...
Is not the beginning of a noun phrase. Learn is the infinitive form.
Learning is a participle form, and can be used as the beginning of a noun phrase.
So if we had
Your twelve times table is important to learn about mathematics.
There to is the infinitive marker for learn and not a preposition (as it is in the phrase important to). So that breaks down into "Your twelve times table is important" and "to learn about mathematics" and is an example of elision: the more easily understandable sentence would be
Your twelve times table is important in order to learn about mathematics.
And the original should probably join the two parts with a comma.
Your twelve times table is important to learning about mathematics.
Breaks down into "Your twelve times table is important to" and "learning about mathematics", so is not eliding anything and doesn't need a comma.