Somebody rents a field from his friend in a sharecropping agreement: he will hand over a percentage of the yield to the owner. The field did not produce much. When the sharecropper went to deal with the crops, he saw that not much had grown and did not think it was worth tending to them. He would like to leave them and wait for a different season. He does not want to deal with whatever is there.
But the owner of the field is paid only through sharecropping; he gets a percentage of whatever grows. So he wants the sharecropper to do his job and produce whatever crops he can, because the owner gets only a percentage of that. He would like the sharecropper to continue working.
So we say: if there is enough produce growing that, when harvested, it could form a pile of grain, the sharecropper has to continue taking care of the field. But if the field would not produce that amount of grain, the sharecropper is allowed to abandon the field, leave the crops, and not tend to them. Then the owner would not get anything.
When a sharecropping agreement is made, there is usually a document saying that the sharecropper will work the field, plow it, plant it, and eventually hand over a pile of grain. We deduce from that contract that if the field could produce enough for the sharecropper to fulfill his agreement and give over a pile of grain, he would be obligated to do so. This applies even if there was no contract. We say that these laws apply automatically unless specified otherwise if there was a deal between a sharecropper and the owner of the land.
Rabbi Yehuda disagrees. “I’m not Rabbi Yehuda.” Why is there a set amount that we are saying—a pile of grain? Why does that apply to every field? It should depend on the size of the field. If you are dealing with a large field, then it needs more work than a small field. Therefore, a large field would need a bigger pile to make it worth the sharecropper’s while. It has to be worth the effort for him. So a large field would have to produce a bigger pile, while a smaller field would have to produce a smaller pile for the owner.
So what measurement do we use to figure out whether the sharecropper should continue working the field, or is obligated to work it? As much grain as was originally used to plant the field: if it could produce that, then he would be obligated to continue working the field and give over a percentage to the owner. If it could generate... As much as when invested into it, then the sharecropper would be obligated to continue to work.