Edaphology is the science of how soil impacts living things. It also looks at the ways we use soil and how that use alters a soil’s ability to support life.
There’s no denying that a lot is going on under our feet. Within the soil, one might find worms, spiders, tiny beetle eggs, or a colony of ground-dwelling bees or ants. You might also find billions of bacteria and trillions of fungi and other microorganisms. But it is the condition of the soil that makes life possible for all those living things.
Edaphology is the study of how soil is used in agriculture (agrology) and how soil impacts the local environment (environmental soil science). As gardeners, we are all amateur edaphologists, to one degree or another.
By studying soil biology, physics, and chemistry, edaphologists have learned a lot about how soil can be used and improved for growing food and other plants. Soil chemistry refers to the mineral nutrients found in the soil that are used by plants as food. Levels of these nutrients, and their availability, often dictate which plants can be grown and how they will perform, as well as what needs to be added or reduced. It also refers to the presence of toxins, such as lead. Only a lab-based soil test can give you that information.
Drainage and irrigation
Agricultural edaphology also looks at irrigation and drainage. Different soils hold and release different amounts of water at different rates. While sand holds very little water, drainage is excellent. Clay holds tightly to a significant amount of water, but drainage tends to be poor. For plants to really thrive, a middle ground is ideal.
Edaphology studies ways to reduce erosion and soil degradation. Bare earth is vulnerable to erosion. Ask anyone who lived through the Dust Bowl of the 1930s. Wind, water, animals, tools and equipment can all degrade or erode soil, one way or another. Soil degradation also refers to the depletion of water-soluble nutrients used by plants. Climate and vegetation play major roles in soil degradation. As temperatures rise (or fall), different sets of plants, microorganisms, and other life forms thrive or suffer, impacting your soil.
Edaphology has found ways to improve soil fertility and structure, along with its cation exchange capacity and its water holding capacity by adding soil amendments. Soil amendments include fertilizers and soil conditioners. Soil conditioners are used to improve or rebuild damaged soil. Bone meal, blood meal, coffee grounds, compost, manure, and vermiculite are just a few of the soil amendments used to improve soil quality. These materials help reduce soil compaction and improve nutrient levels and accessibility. Adding organic materials, such as aged compost, can significantly improve water retention and drainage.
Edaphologists have researched the various properties of soil in relation to plant production. Their research has taught us better soil husbandry methods. Soil husbandry is the art and science of caring for soil so that it can continue to be used to grow the plants we want. Soil husbandry includes protecting soil from erosion and degradation with mulch and cover crops, improving soil with soil amendments, and employing green manures and crop rotation to keep soil healthy. Whatever is growing on top of a soil has a profound impact on the health, structure, and fertility of that soil.
The bottom line for gardeners is that edaphology teaches us how healthy soil creates healthy plants and healthy plants help maintain healthy soil.
Now we know.
You can grow a surprising amount of food in your own yard. Ask me how!
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