Compost provides a balanced source of plant nutrients. Even if you are lucky enough to have great soil, you can t expect that soil to remain rich and productive without replenishing the nutrients that are consumed each growing season. No commercial fertilizer, even one that is totally organic, provides the full spectrum of nutrients that you get with compost. The nutrients are available gradually, as your plants need them, over a period of months or years. The microorganisms in the compost will also help your plants absorb nutrients from fertilizers more efficiently.
Compost stimulates beneficial organisms.
Compost is teeming with all kinds of microorganisms and soil fauna that help convert soil nutrients into a form that can be readily absorbed by your plants. The microorganisms, enzymes, vitamins and natural antibiotics that are present in compost actually help prevent many soil pathogens from harming your plants. Earthworms, millipedes, and other macro-organisms tunnel through your soil, opening up passageways for air and water to reach your plants roots. Compost is garden insurance. Even very experienced gardeners often have soil that is less than perfect.