The third and final main principle in CA is a healthy crop rotation. A monoculture-based crop rotation increases the risk of weeds, diseases and pests multiplying. This can to some extent be remedied by tillage, but as tillage is not used in CA, it is important to switch between crops so that the same crop is never grown two years in a row unless it is a perennial crop.
In the CA system, you have a larger frequency of spring crops than in a traditionally tilled system, partly because there must be room for the cultivation of cover crops in the crop rotation.
Spring crops provide better opportunities to control weeds and at the same time provide the opportunity to grow cover crops, which are also an important element in CA.