I find that people are often confused by the terms Compost and amendments.
Compost is basically any product applied over the area of the dirt, to either cool down or to warm the dirt and at the same time preserve water. It may be more proper to contact Compost, area Compost. Compost is commonly used to keep the dirt cool and to preserve water by preventing the water from evaporating out of the dirt. Mulches can be organic components like decorative bark, compost or even straw. Mulches can also be inorganic like decorative rock, gravel or sand. Amendments are components added into the dirt to improve the physical or chemical make-up of the dirt.
Cooling mulches are extremely good for vegetable gardens and flowerbeds during hot weather. Compost helps keeps the dirt cool and evenly moist, which benefits both flowers and vegetables. Cooling mulches include compost, decorative bark (all sizes and types) and even newspaper. Newspaper can be a problem because it blows real easy, and the colored papers can release ink, which can become a problem.
In your vegetable garden, straw can also be a good Compost. Straw can be spread out during the summer and then removed and composted at the end of summer allowing the dirt to heat up in the fall. Straw or sawdust can become a problem if left on the dirt too long. Even on top of the dirt, straw or sawdust will deplete the nitrogen out of the dirt.
Besides conserving water, mulches have other benefits. Mulches can either cool down or heat up the dirt. In late spring or early summer we can place clear or dark plastic material over our garden beds. Just cut holes in the plastic material to plant your summer vegetables. The plastic material will heat up the dirt and allow vegetable seeds to germinate faster and the plants to improve faster.
As the summer heats up, cover the plastic material with straw or compost or other organic material about three inches deep. This will cool down the dirt during the hot months. When the summer fades into fall remove the organic Compost and expose the plastic material, so the dirt will stay warm and your vegetables continue to improve.
That is an example of how to use mulches in your garden and how to extend your growing season. Even if you do not use the plastic material layer, a cooling Compost in the summer is very important and can benefit your garden.
Mulches can also prevent weeds by suffocating weed seeds. With three inches of Compost, very few weeds will improve and those that do improve can easily be pulled out.