rick's user sample comments on PR

[miladagreen]

The User Sampled branch needs a cash crop planting date (found on the Cash Crop tab), and a cover crop termination date (found on the Cover Crop tab). Note that these dates should not have default values.

The program has unspecified planting and termination dates on the Location tab. I think these can go away.

The planting date on the Location tab is actually the cover crop planting date, which isn't needed for the User Sampled branch. (I'm also unsure why it's needed in the Satellite branch, but I need to study that some more.)