How do soils work?
Soils are much more than an inert mass of sand, silt, and clay. They are an interconnected community of living or dead organisms, physical and chemical factors, and processes that create
an ecosystem. Recognizing soil as an ecosystem helps us understand how a healthy soil functions as well as how limits on any part of the system can cause it to function poorly or fail. Knowing the roles of various players in the soil food web helps us foster healthy, highly functioning soil that is productive and resistant to drought, erosion and other external factors.
What is the habitat for soil microbes?
The pore spaces in the soil formed by the creation of aggregates are the vital habitat for the diverse community of microbes.
Plants provide the primary food
source for the soil ecosystem.
Living plants or decomposing
dead plant tissues feed hosts of
soil microbes. Living plant roots
actively exude sugars, amino acids and other compounds into the soil. This happens in the rhizosphere – a narrow region of soil surrounding the root. Dead plant tissues include residues on the soil surface or roots in the soil.
the soil food web can be broken down into numerous trophic (feeding) levels. Starting with plants converting the sun’s energy into sugars, the web includes a diversity of predatory, decomposing, and grazing microbes. Disrupting any of these levels can cause the soil food web to break down, resulting in unhealthy, unproductive soil.
How is habitat for soil microbes created?
Mycorrhizal fungi, bacteria, protozoa, nematodes, enchytraeids, and earthworms exude polysaccharides, glomalin, organic acids, and amino acids. These combine with exudates released by plant roots to work as glues to bind soil particles (sand, silt, and clay) into larger and larger aggregates. This forms the soil’s granular structure. Aggregated soil also provides pore spaces for larger organisms like protozoa, nematodes, enchytraeids, earthworms, insects, and mites to thrive.
When soil habitat is undisturbed soil organisms burrow, shred residue, and create larger pore spaces. The result is a vast network of channels, nooks, and crannies that improve root growth as well as water and oxygen infiltration, allowing a diverse community of soil microbes to flourish.
How do plants and soil microbes help each other?
Plants feed soil organisms that in return provide nutrients to the plants. Microbes break down existing organic matter or mineral soil, making nutrients more available to the plant.
What are the results of healthy soils?
Managing for soil health gradually improves compacted or disrupted soil. Healthy soils have greater pore space enabling increased water infiltration, resulting in less ponding and runoff. Better porosity also allows for a deeper and more extensive root mass. A diverse community of soil organisms living in a favorable habitat can provide more beneficial services to the plants.
Improved nutrient cycling
Increased water infiltration and availability
Improved physical support and structure
Enhanced soil habitat for increased biodiversity
Filtering and buffering to protect water quality
What is our role in soil health?
The loss or reduction of any of the key processes in soil function can be detrimental to the entire soil ecosystem. Understanding the interconnection in the soil ecosystem helps us manage our soils differently to improve soil health.
Tillage and other mechanical disturbance destroys soil structure (the aggregates) and results in the habitat loss for the majority of the organisms required for healthy soil. The absence of living plants (fallow periods) interrupts the food web – no plants present to create the sugars that feed the soil microbes. Loss of soil cover leaves the soil unprotected against the elements causing extreme swings in temperatures and excessive evaporation of soil water. The result of this type of management is a desert landscape, both above and below the soil surface.
What can you do?
Though the soil food web is a complex system with a diverse range of components and processes, you can promote healthy soils following four principles:
Keep the soil covered as much as possible
Minimize soil disturbance
Keep plants growing throughout the year to feed the soil microbes
Diversify plants grown in the soil as much as possibleusing crop rotation and cover crops
Applying these basic principles can significantly improve the function and productivity of the soil. A properly functioning soil cycles nutrients, has good water infiltration, and stores water in its pore spaces. Resilient soils provide physical stability and support as soil structure is improved.
Soil supports the growth of a variety of plants, animals, and soil microorganisms. Providing a diverse physical, chemical, and biological habitat will ultimately be more profitable for the producer.
What is soil made of? As a dynamic natural system, soils are made up of the following components: inorganic mineral particles (sand, silt and clay, gravel, stones and rock), organic matter, air, water and living organisms. The specific contribution of these different components to the soil system has a prominent effect on soil functions and depends on soil type, and its related forming factors. Man-made materials may also form part of the soil.
How do soils make plants grow? Soils support plant growth by providing anchorage, sufficient oxygen, moisture and nutrients. Additionally, soil protects roots from drastic fluctuations in temperature by buffering temperature modification.
How are soils formed? There are many different factors that come together to create soils, and the process can take thousands of years to reach an equilibrium. The main soil forming factors are: climate, topography, parent material, time and biological factors (plants, animals, micro-organisms and humans). Different combinations and intensities of soil forming factors lead to different soil types.