Answer:
- crop rotation
- selective breeding
- using arable land better
Step-by-step explanation:
-> crop rotation
[] Crop rotation is where the crops are, well, rotated. This keeps to land from being drained of one nutrient too much that one crop may use a lot of, but the other may not. It also usually gives crops an "off-season" of some sort where they can get their nutrients back.
[] using arable land better is a part of crop rotation
-> selective breeding
[] This is where humans, in both plants and animals, breed, select the best ones, breed those, and continue. For example, lettuce did not used to be as "full" as it is today, but with selective breeding the "thickest" lettuce heads were kept, continuing to proccess.
Have a nice day!
I hope this is what you are looking for, but if not - comment! I will edit and update my answer accordingly.
- Heather