What are diagnostic horizons in soil science?

✅Explanation:
Diagnostic horizons in soil science are layers within a soil profile that have distinct characteristics and properties. These horizons are formed as a result of soil-forming processes, also known as pedogenesis, and they serve as key indicators for classifying and identifying different soil types. These characteristics can include texture, mineral content, color, or other features that help in soil classification.
a. Layers formed as a result of soil-forming processes (pedogenesis): Diagnostic horizons are formed through soil-forming processes, such as weathering, leaching, and organic matter decomposition.
b. Horizons with distinct characteristics and properties: Diagnostic horizons have distinct features that help in soil identification and classification.

🛑 Additional Information::
Soil Profile: 
-It is the vertical section of soil from all its horizons. 
-There are different types of soil, each with its own set of characteristics.
-It is made of layers, or horizons (O, A, E, B, C, R). 
-Put the horizons together, and they form a soil profile.
-Most soil profiles cover the earth as 2 main layers Topsoil and Subsoil.
-Most soils have three major horizons (A, B, C) and some have an organic horizon (O).
A. Horizon or Surface soil
-It is the part of topsoil.
-In this layer, organic matter is mixed with mineral matter.
-It is the layer of mineral soil with the most organic matter accumulation and soil life.
-Nutrients like iron, aluminum, clay, and organic matter are sometimes dissolved and carried out in this layer.
-This layer is depleted of (eluviated of) iron, clay, aluminum, organic compounds, and other soluble constituents.
-When depletion is pronounced, a lighter colored “E” subsurface soil horizon is apparent at the base of the “A” horizon.
B. Horizon or Subsoil
-It is a subsurface layer reflecting chemical or physical alteration of the parent material.
-This layer accumulates all the leached minerals from the A and E horizon.
-Thus iron, clay, aluminum, and organic compounds accumulate in this horizon (illuviation)
C. Horizon or Parent rock
-Weathered parent material accumulates in this layer, i.e. the parent material in sedimentary deposits.
-It is a layer of large unbroken rocks.
-This layer may accumulate more soluble compounds (inorganic material).
R. Horizon or Bedrock
-This layer denotes the layer of partially weathered bedrock at the base of the soil profile.
-Unlike the above layers, R horizons largely comprise continuous masses of hard rock.
-Soils formed in situ will exhibit strong similarities to this bedrock layer.
-These areas of bedrock are under 50 feet of the other profiles.
-It is also known as D horizon in some cases.

• O. Horizon:
-Layers dominated by organic material.
-Some O layers consist of undecomposed or partially decomposed litter (such as leaves, needles, twigs, moss, and lichens).
-They may be on top of either mineral or organic soils.

• E. horizon:
-“E” stands for eluviated layer.
-It is a light-colored eluviated layer, that is eroded by its nutrients.
-It is the horizon that has been significantly leached of clay, iron, and aluminum oxides, which leaves a concentration of resistant minerals, such as quartz, in the sand and silt sizes.
-These are present only in older, well-developed soils, and generally occur between the A and B horizons.