Soil, the Key to Life

As you probably know, I am an Elected Directory of the Prince William County Soil and Water Conservation District. Our mission is to protect the soil and water resources of the county and region. Though I usually focus on water, soil is just as important and always underappreciated. Soil is an ecological system a living ecosystem that sustains all life on earth. Maintaining soil health is essential not just for farming but also for maintaining the health of ourselves and our planet.

As Sir Albert Howard, the father of the organic movement said, Soil is an ecological system where the microbes and organisms in the soil provide a living connection between the soil humus and plants. The microbial decomposition of organic matter forms the humus, a spongy substance rich in nutrients and essential to soil fertility. A teaspoon of soil can contain millions upon millions of bacteria and fungi. These bacteria and fungi produce enzymes and acids necessary to break down inorganic minerals and to convert them into forms that can be absorbed by plants.

The fungi in the soil are microscopic plant-like cells that grow in long threadlike structures called hyphae. These hyphae push their way between soil particles, plant roots and rocks. The hyphae make a mass called mycelium. The mycelium absorbs nutrients from the roots, surface organic matter or the soil. The fungal hyphae and a protein that the fungi create called glomalin bind the soil particles together with a coating of the protein to create water-stable aggregates which in turn create the pore spaces in the soil that enhance water retention and drainage and give soil its structure. Good structure from healthy soil with thriving microorganisms can allow soil to retain water during a drought and reduce the need to irrigate.

The bacteria in soil also help decompose organic material and improve soil structure. Bacteria perform biological nitrogen fixation, the process that changes inert N2 to biologically useful NH3. All living things need nitrogen and though about 80% of the atmosphere is nitrogen gas (N2) in this form N2 is unusable by most living organisms. All organisms use the ammonia (NH3) form of nitrogen to manufacture amino acids, proteins, nucleic acids, and other nitrogen-containing components necessary for life.

Bacteria supply the nitrogen useful to plants either directly from the bacteria when they die and release usable nitrogen to their soil environment, or when the bacteria live in close association with the plant. In legumes and a few other plants, the bacteria live in small growths on the roots called nodules. Within these nodules, nitrogen fixation is done by the bacteria, and the NH3 produced is absorbed by the plant. The amount of nitrogen returned to the soil depends on how much of the plant is left in the field. Almost all of the nitrogen fixed goes directly into the plant so nitrogen only returns to the soil for a neighboring plant when vegetation (roots, leaves, fruits) of the legume die and decompose.

We know so little about how the ecology of soil impacts food, animals and our own human gut microbiota. Yet the profound fact is that all life is dependent on the life of the soil. The two things which have the most impact on the health of the soil are tillage and chemicals. Tillage causes erosion of the top soil where most of the micro-organisms live. Initially tillage frees up all the food for microorganism to consume, but over time the microorganisms begin to starve as all the organic material is consumed and not replaced. In unsustainable agriculture the next step is to add chemicals and synthetic (or organic) nutrients.

By Elaine Ingram author of Soil Biology Primer

Chemicals can be toxic to organisms in the soil. The full impact of the hundreds of chemicals present in pesticide, herbicide and nutrient formulations is little understood. Sustainable agriculture requires sustainable soil. The soil must have a balanced diversity of organisms working in harmony to continually produce plants that are the food for the rest of the planet. What changes within our microbiota might be caused by poor management of soil health?