A variety of levels, called horizons, lurks below the garden topsoil.
Gardeners match the plant to the soil's pH and texture. The term pH refers to the level of acidity in the soil. Many gardeners do not analyze how the soil itself contributes to its pH. That may be because pH is a function of chemistry rather than compost. Does this Spark an idea?
All Soil Is Not the Same
All soil descends from rock, erosion, dead plants and animals.
The soil in the garden is the result of eons worth of rock erosion, chance collisions with space debris and millions of years of living organism growth and death without people raking up or burying the debris. Beginning as gravel and sand, soil becomes silt and then clay, as its components become ever smaller. Areas rich in organic matter develop quick-draining loam; deserts remain sandy with patches of marginally fertile soil; and riverbeds fill with silt, creating layers of different major types of soil, called series. Soil tests classify soil series and subgroup as well as nutrient content and acidity or alkalinity.
Soil Differences
Water gets minerals, hydrogen and hydroxides from soil.
The geologic and climatological events that shaped soil differed across the shifting continents, leaving differing mixtures of minerals, organic matter, liquid and gases in each eon's layer of soil. The soil created was not a compound but a mixture of compounds, some with unsecured hydrogen ions and others with excess hydroxides. Weather patterns and agricultural chemicals further altered soil types.
Determining pH
Indicators react with acids or alkali suspended in water.
Tests for the level of acidity in the soil begin with a solution of soil in distilled water. Chemicals, called indicators turn colors when added to the solution as they encounter hydrogen ions and hydroxides. The color created by the indicators corresponds to a scale from 0 to 14 representing degree of acidity or alkalinity of the water. This is the test that homeowners rely upon to decide whether to add lime or sulfur to change the soil's pH.
Soil and Water
Adjacent soils contribute to water's pH.
Bodies of water are not insulated from the soils around them, and water travels downward through aquifers, layers of soil and rock. Calcium, sulfur, potassium and other chemicals leach from the soil and aquifer into the water body affecting the water's pH. Smaller bodies of water may acquire more alkalinity or acidity, but larger bodies draw from a larger soil sample. Bodies of water are part of a water cycle. Water evaporates and forms clouds that condense and fall to earth as precipitation. On its way through the evaporation and condensation phases, gases such as sulfur dioxide contribute to water's pH. As the water passes through watersheds and rivers, soil contributes the chemicals that determine the pH of earth's waters.
Tags: acidity alkalinity, acidity soil, contribute water, from soil, hydrogen ions
