Salem

So i filled my field with humus and i try to put seeds on the field it wont let me do i need a skill to plant them? Help me please.

Depends on the state of the corn.
If they are baby corn it wont happen.

for actually planting corn seeds you'll need just Agriculture, which you should have when you're able to till a field.

may sound like I think you're stupid, but it happens a lot : are you sure you have put enough humus ? and are you sure you have enough seeds ?

If you make upkeep %50 ( it means 7 or 8 wood choping you need to put a field. ) you can put 2 humuses instead of 5 humuses. To make upkeep %50 will let you use less seeds than %100 upkeep( standart field value)

For example % 100 upkeep field wastes 50 cereal seeds but %50 upkeep field wastes 25 seeds.

If you can't plant corn to your fields,

1- Put more humuses to your field than you did before.
2- Supply more seeds. For example Put 50 seeds instead of you putted before.

I don't recommend you to plant corns. They are not useful. It's just waste of time.