It appears that the placed farming lands have some graphical issues that make using them a bit of a pain.
The graphic for the dirt patches appears to have layering issues with the crops themselves, at times rendering over the crop so that you have just a few pixels available to actually select the plant.
Here we have a 0.15 zoom, which is necessary for ensuring all plants are properly taken care of in lieu of having all the appropriate equipment and resources for spreaders, hoses, etc. If you note the small purple object in the center, that is all that is visible of this particular corn plant.
![Image](https://i.imgur.com/S19WKIj.png)
Here is a standard zoom screenshot for comparison of visibility, the crop once again highlighted purple.
![Image](https://i.imgur.com/MuiAJK5.png)
We can also see that some of the patches do not render at all, and I have seen other placed farms that there is no dirt visible whatsoever.
Another visibility issue are the pieces of tall grass that poke through the dirt, though I admit I am not sure if this is a map conflict with the dirt plots or a piece of the farming mechanic I do not yet understand. It does not appear to be grass that is able to be pulled.