What was the effect of the three-field system?

The purpose of 3 field crop rotation was to allow fields a chance to regain minerals in between periods of growing crops. Every time a crop is planted and harvested, minerals are lost from the soil. This is due to the plants taking them from the soil to aid their growth. To prevent the fields becoming infertile a 3 field crop rotation system can be used to help with this problem. By not using one field, or planting crops (such as clover) which return nutrients to the soil, it could maintain a good amount of crop produced each year without making the fields infertile.