Soul of Soil

humus in the soil profile

The soil should be viewed as a living breathing organism in and of itself.  It carries out multiple functions in plant-life.  Some are obvious.  Some are not so obvious.

Supporting The Plant and Root System

The soil functions as a physical medium to hold the plant upright and provide a home for the plants roots.  For this reason, for most taller plants, the soil has to have a certain degree of “structure”.  The structure defines how the soil holds together.  The soil is held together through attraction of the particulate matter of the soil.  A soil made up of very tiny particles is usually classified as a clay, and a much larger granular structure would be sand or gravel. In general, the smaller the particles of soil, the denser the packing of the particles and the less room for water infiltration and gas exchange.  Both of these are critical for the health of the plant and the plant’s root system.

Supplying Mineral Nutrition

The soil carries out a second function, and that is of supplying the mineral nutrition to the plant.  Absent some form of fertilization, the minerals inherently in the soil will be due to the parent material that the soil derived from.  Soils are often the result of countless eons of weathering, water-flow and/or volcanic activity which deposit layers of sediment, ash, or minerals on an area over time.

Organic Material

As plants start to take hold and then die off, organic material is deposited into the soil. Critically important to developing a healthy, robust, soil for plant development is the development of humus.  Humus refers to the fraction of organic matter in the soil that is amorphous and cannot be distinguished as a plant or animal organism.

Humus refers to the fraction of organic matter in the soil that is amorphous and cannot be distinguished as a plant or animal organism.

Humus is thought to be made up of decayed plant or animal material that has undergone such a transformation that the elements that make it up are indistinguishable from each other.  What is known is that humus is critically important to the nutrient and water holding capacity of a soil and soils with large humus deposits and generally thought of as healthy soils and are grow plants and crops more resilient to drought, disease and pest stress.

Biology In The Soil

What’s less well known is that soil is not a sterile medium – regardless of what the hydroponic growers would have you think.  It is a living web of interactions taking place on an often times microscopic level.  Literally billions of microbes live, work, and replicate in every shovelful of soil.  They carry out many of the unseen tasks that provide a healthy environment for your plants and it’s all provided by nature.  While it’s very possible to damage the microbial population in your soil by overuse of chemicals and fertilizers, it’s inadvisable to do so.  Those that do find themselves trying to replicate the tasks of watering, feeding, and protecting the plants they are trying to grow from pests that the microbes would ordinarily be providing for them.

Caring for Our Soils

Your soils are more than meets the eye.  They carry out a multitude of functions and provide your plants with all they need to thrive, survive and reproduce.  The bounty the plants provide in turn provide all the sustenance the animal kingdom — including us — requires.  Caring for the earth, means we must care for our soils.