It is always important to recognize soil odor to tell if the ground or compost will contribute to your plantâ€™s overall growth. Use good judgment to decide whether the soil has an odor that will either be detrimental or help plants grow productively. Soil should always have a fresh earthy smell that is natural. If natural soil has a bad smell, a chemical balance may likely be off, or you may have harmful microbes in the soil. If your soil bed has a bad smell, you can test soil quality through the mail-in testers or add the necessary compost as a support mechanism. Compost should not have a foul smell and should be as natural as possible. If you make your compost, be sure the items you use to make compost are not infected with any diseased plants, harmful microbes, and fungus. People often confuse compost with manure which is known for its foul smell. The only type of supportive soil that should smell bad is manure unless you choose to mix manure in the compost. If your compost smells, there are some things to consider, such as your balance of brown and green plants. If there is any off-balance, then too many green plants will give off a sewage odor or may also emit an ammonia-like scent. That is no way to garden, and it will make for an unpleasant experience while gardening and may attract complaints from neighbors. Try adding more brown items like straw, leaves, and newspaper to bring your compost back to proper balance. You may also have problems layering the mixture of materials instead of adding them together. Make sure the compost pile is mixed correctly and is not too compacted. Compost needs oxygen and aeration to rot effectively to produce healthy microbes that will benefit your garden. Too little oxygen will make any compost pile stink. The same applies to moisture. Excessive moisture will filter out the aeration process and further compact your compost. If you live in an area that rains frequently, try adding compost in an area protected from the outside elements, like under an outside deck or someplace that has shading yet gets plenty of oxygen. Any compost pile that has a putrid sewage odor or a lingering smell of rotting eggs is a pile that needs to be reapplied and added with the right ingredients that will make it fresh once more, or you may need to discard an entire pile.