5.2 - Soil Orders | Soil Genesis and Development, Lesson 5 (2024)

FAQs

How to memorize soil orders? ›

Here's the mnemonic device for soil orders: "Give Him A Very Moldy Soap Or U Are An Incompetent Entity" for Gelisols, Histosols, Aridisols, Vertisols, Mollisols, Spodosols, Oxisols, Ultisols, Alfisols, Andisols, Inceptisols, Entisols.

Alfisols are more common under forests in cooler, drier climates and younger landscapes where weathering, leaching, and removal of bases is not as extensive. Ultisols occur in warmer, wetter, and more stable landscapes of the region where soils have weathered more and base saturations are consequently lower.

Alfisols are in semiarid to moist areas. The central concept of Alfisols is that of soils that have an argillic, a kandic, or a natric horizon and a base saturation of 35% or greater. They typically have an ochric epipedon, but may have an umbric epipedon.

List the six soil horizons in order from top to bottom. (mnemonic: Orange Apes Eat Boston Creme Donuts.

Soil scientists use the capital letters O, A, B, C, and E to identify the master horizons, and lowercase letters for distinctions of these horizons. Most soils have three major horizons -- the surface horizon (A), the subsoil (B), and the substratum (C).

Ultisols vary in color from purplish-red, to a bright reddish-orange, to pale yellowish-orange and (in cooler areas such as Pennsylvania) even some subdued yellowish-brown or grayish-brown tones. They are typically quite acidic, often having a pH of less than 5.

The "red clay" soils of the southeastern United States are examples of Ultisols. They are divided into five suborders: Aquults, Humults, Udults, Ustults and Xerults. Because of the favorable climate regimes in which they are typically found, Ultisols often support productive forests.

GENESIS/FORMATION OF ALFISOLS

Alfisols form in loamy parent materials that are not too sandy or too clayey under semiarid tohumid areas, typically under hardwood forest cover vegetation. These soils are well developed and contain a subsurface horizon in which clays have accumulated.

The principal agricultural crops grown on Alfisols are corn (maize), wheat, and wine grapes. Alfisols typically exhibit well-developed, contrasting soil horizons (layers) depleted in calcium carbonate but enriched in aluminum- and iron-bearing minerals.

What is Ultisols soil good for? ›

Ultisols an ochric epipedon and an argillic or kandic horizon that has few bases and commonly is calcium deficient. Most of these soils supported mixed coniferous and hardwood forest vegetation at the time of settlement. Some are now used as cropland or pasture.

Ultisols are intensely weathered soils of warm and humid climates. They are typically formed on older geologic locations in parent material that is already extensively weathered. The B horizon is typically a mineral subsurface horizon.

Alfisols, Ultisols and Spodosols are associated mainly with forested landscapes and Mollisols mainly with grasslands.

Alfisols are moderately leached soils that have relatively high native fertility. These soils have mainly formed under forest and have a subsurface horizon in which clays have accumulated. Alfisols are primarily found in temperate humid and subhumid regions of the world.

Called the A horizon, the topsoil is usually the darkest layer of the soil because it has the highest proportion of organic material. The topsoil is the region of most intense biological activity: insects, worms, and other animals burrow through it and plants stretch their roots down into it.

Biology. To remember the order of taxa in biology (Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species, [Variety]): "Dear King Philip Came Over For Good Soup" is often cited as a non-vulgar method for teaching students to memorize the taxonomic classification of system.

Hence, the sequence represents a correct order of soil particles arranged in terms of particle size from smaller to largest is Clay < Silt < Sand < Gravel.

The correct sequence of soil layers from top to bottom is typically topsoil (A-horizon), subsoil (B-horizon), and C-horizon.

Pedology, the study of soils in their natural environment, is important to understanding topics such as evolutionary pathways of ecosystems and how humans have historically interacted with soils. We study and inventory soil landscapes by survey and other methods.