If it hadn't been for the chemical revolution in the first half of the twentieth century, gardeners would have concentrated their efforts on improving the biological component of the soil instead. Indeed, the emphasis on chemicals, often synthetic chemicals, was the accepted practice to greatly increase harvests rather than improving organic content and stimulating specific microbial life to match the crop. Today, however, more and more attention is paid to this biological side. For healthy plants, the soil must be alive with soil life and it must contain food for the soil organisms. Gardening practised in this manner promotes increasing long term health and benefits instead of short term gain where soil vitality decreases each year.