Soil needs plants in the same way plants need soil

Soil has evolved to support plants and not to be without plants. If left for any length of time without plants it soon becomes de-structured poorly draining and a hostile environment for all the soil organism that work in the soil to breakdown organic matter etc
If you find yourself with a bare patch of soil that is going to be bare for more than 6 weeks you should consider growing a green manure such as clover in the case of a vegetable garden or in other areas of bare soil mulching with mulches such as spent mushroom compost will protect the soil . Both these method will improve the soil an enrich its fertility and organic matter content. Although it should be noted that mushroom compost contains lots of lime and so will raise the soil pH if you have a chalky soil or need to lower the soil pH using well rotted manure will achieve this.
Another method to protect your soil in the short term is to cover the soil with a weed sheeting which as well as smothering the weed seedlings protects the soil the soil structure from the devastating effects of rain and rain drops which smash the surface destroying the crumb structure and de-structuring the soil making it difficult for plant roots to growth into the soil.