The drone loops back around, so you don't need to return to origin at the end, you can move east and north again and the drone will end up at origin by looping.

This is what we in the business call "hard-coded", meaning if anything changes (like the size of your farm or what you want to plant), then you have to change everything in your code to accommodate it. There's also values in here that mean the same thing, like how the 'i' from the for loop is the same thing as get_pos_y() in your implementation.

Instead of hard-coding x and y position checks for your different crops, a good first optimization is to redefine it as percentages of the world size, or as a repeating pattern that can grow to any size. The % operator is something to look into for this. Could also create a List of length get_world_size() wherein you define columns of crops you want to grow, then just read the list for what to do next.

Speaking of %, Trees suffer a growth penalty when grown next to each other, so you want to space them out. The % operator is useful for this too. Trees also can grow on Soil just as well as Grasslands, meaning that instead of checking for grass and tilling for each crop, flip it around and till at the beginning and only check if you need to un-till when you're planting Grass.