tillage present twice?

[cmungall]

I think a mistake was made when implementing @pbuttigieg's request for #33 - tillage was added as a new class, not a synonym

We now have this:

I think tillage and tillage process should be merged

[marieALaporte]

We added both tillage and 'tillage process' to represent different things. The class tillage is a grouping category that we used as often no-till is considered as being part of tillage. No-till is the voluntary choice of not doing a tillage process.
If this distinction is too confusing for users, we can remove it, and just keep the 'tillage process' and no-till class, without grouping them.

[marieALaporte]

@cmungall can I close the issue or do you need to discuss it further?