Hurrah, we come to the end of the module! We started the module by asking why farmers don't always plant the same crop. For example, lakhs of farmers grow rice (paddy) once, and then grow wheat next. They do not grow only wheat or only paddy.
As we saw, this is called Crop Rotation. Paddy and wheat require different temperatures and different nutrients. So, by growing them one after another, the farmer is increasing the total output of his/her crop.
If the same crop is grown multiple times, there won't be enough nutrients in the soil to produce a good output.