The most precious commodity in the garden is its soil. You're composting (right?) to build up the soil.
When you grows veggies, they take the good stuff out of the soil and grow into whatever veggies their seeds indicates they should become. The nutrients in the soil that the plant took need to be replaced.
Two ways to replace and you should do both regardless.
One is to rotates crops. There are several sound strategies for this, such as switching carrots and tomatoes' locations in the garden each year. Two, amend the soil with your compost. Not anyone's compost and most certainly not from the compost your can buy unless you know for sure that it's genuine compost.
Compost is unregulated. There are no standards for it. Bagged compost often contains wood chips that are better used for mulch; plus bagged compost - in my experience - tens to not retain moisture. Moisture retention is one of the majorly major benefits of compost. I've used bagged compost and boy does that stuff dry out in a hurry. You wind up wasting water.
Anyhow, if you're going to grow a garden, you need to consider yourself, really, as a soil apprentice and learn just what kind of dirt the plants you want to grow are going to grow best in. If that's too complicated, then simplify - compost!
