Current State:
Crop Sticks that are used in AgriCraft in order to plant and grow all kinds of Plants are left in place when empty. As well as on Farmland, as well as on custom soil (gravel/custom soil required for metal plants, etc).
With a Plant inside the Crop Sticks the Crop Sticks are "properly" harvested, returning Crop Sticks, seeds and drops/fruits.

Suggestion:
I would not make them try and place Crop Sticks, as that might interfere with other / vanilla crops. Instead I'd suggest that the Farmer tries to place seeds in empty Crop Sticks and harvests the drops / seeds without breaking the crop sticks.