“You only plant some of your fields, allowing the others to get back some of the nutrients that the plants used up. You let the other fields become fertile again by just tilling up whatever grows there.”— Vault Dweller
If the Vault Dweller's Science skill is greater than or equal to 40%, they can inform Curtis that crop rotation is a better alternative to his current farming style. Curtis will then accept this idea as a sensible way to improve his agricultural method, and the Vault Dweller will receive 500 XP. If the Vault Dweller uses the Tell me about option, the Vault Dweller can bypass the skill check by asking about crop rotation (typing anything appears to work; however there is no reputation bonus for completing the quest this way).
However, if the Vault Dweller's Science skill is less than 40%, the special dialogue option will not appear. If he does not meet the skill requirement the first time, he cannot complete this quest, as he gets only one opportunity to ask Curtis about farming.