Humus Humus is the basis for soil life. Without humus, plants get no naturally formed nitrogen. Without naturally formed nitrogen, plants become weak and more susceptible to disease, drought and insect attack. Humus mechanically loosens the soil and creates a texture called good tilth. Tilth Good tilth means soil is soft, porous, easy to work and crumbles easily into fine pieces.
Water penetrates the soil better and the soil also holds more water.
Tilth prevents the formation of hard crusts on the soil's surface. It allows plants to put out larger root systems easily. When there is lots of air in the soil, microorganisms flourish and speed mineral release. Good tilth allows delicate seedlings to get a good start. With poor tilth, on the other hand, the soil compacts and will not absorb or release water well, seeds do not germinate, root systems decrease and plants suffer more from drought, disease and lack of nutrients.