Is it the field or the farmer that is responsible for removing thistles and rocks so the crops can grow?

As a child, I d hear teachers talking about the parable of the sower. They d get to the bit about the thorns and weeds choking the plants, and the rocky soil killing the plants. The implication always seemed to be, try not to be a weed-covered stony field . But is it the job of the field [ ]