Two important aspects of a healthy soil are ample organic matter and humus and soil microorganisms. Building soil humus improves its physical and chemical properties as well as its biological health. Humus is one form of organic matter that has undergone some degree of decomposition. Humus is dark brown, porous, spongy and somewhat gummy and has an earthy aroma. Finished compost is an excellent source of humus.
Soil microbes are the essential link between mineral reserves and plant growth.