Why is the life in your soil so important?

The entire food production system depends for its viability on healthy soil. Healthy soil produces the healthy crops that give nourishment to people. Organic farming is intimately related to the concept of soil health because its advocates have always believed that a healthy soil is the key to the sustained production of healthy, nutritious food.

The main indicators of soil health are the amount of fresh organic matter and the level of biological activity. Soil is a living ecosystem, and healthy soil is filled with different organisms, microscopic and larger ones, responsible for converting minerals and decomposing matter into nutrients plants can use. The microscopic organisms include bacteria, viruses, protozoa, fungi and algae. The larger fauna include earthworms, insects, and mammals such as moles, mice and rabbits (which live in the soil at certain stages of their life cycle). Biological activity is dependent on organic matter content.

The organic matter in soil comes mostly from dead plant tissue. Plant residue consists principally of moisture (60-90%), but the dry matter in it has many elements including carbon, oxygen, hydrogen, some sulphur, calcium, magnesium, as well as nitrogen, phosphorous, and potassium. It has an active component that includes microbes (10-40%) and a stable component often called humus (40-60%). These components (or fractions) are not end products but are involved in a dynamic process. The decomposition rate of soil organic matter depends on soil properties such as texture, temperature, moisture, pH, aeration, mineralogy and soil biology, for example. In turn, the soil organic matter influences the said soil properties.

Organic matter is rich in nutrients, which are returned to the soil in a form readily available to plants. This nutrient cycling loop should be maintained if soil is to remain healthy. This means that organic matter should be added (from crop residues, manure, and other sources) at a rate equal to or greater than the rate of consumption or decomposition, taking into account the rate of usage by plants and losses by erosion and leaching. If the rate of addition is less than decomposition, soil organic matter declines along with soil health.

Both the active and stable components of soil organic matter, in combination with microbes particularly earthworms and fungi, play significant roles in the formation of bigger aggregates from fine particles of organic matter and mineral material. Aggregates are crucial for good soil structure, aeration, water infiltration and holding capacity, and ability to withstand erosion.

A healthy soil system, then, involves not only soil fertility but also soil structure, acid build-up and erosion. Its functions include the conversion of decaying organic matter into stable humus, the retention of various nutrients including nitrogen and delivery of nutrients in a form plants can readily assimilate, the formation of aggregates, the protection of root systems from parasites and diseases, the production of plant hormones to promote growth, and the retention of water.

Farmers need to have healthy soil in order to sustain their food production activities. Exploitative farming systems draw nutrients from the soil without fully replenishing them and restoring soil quality. Organic farmers can do many things to maintain, enhance and rebuild the soils in their farms. They have many options available to them.