8 Characteristics of Soil

Soil is the superficial layer of the Earth’s crust, basically formed by mineral agglomerates and organic matter from the decomposition of animals and plants.

This natural element is of fundamental importance for the life of several species. The soil serves as a source of nutrients for plants, and its composition directly interferes with agricultural production.

Characteristics

These are characteristics present and observable in soils that allow us to distinguish a certain type of soil from others. Some characteristics that are commonly observed in the morphological description of soils are:

Color

It is easy to identify and makes it possible to make inferences regarding the content of organic matter, types of iron oxides, formation processes, among others.

In order to have a soil color identification pattern, the Munsell Color Charts are used , which considers color variations on three-component scales: hue, value and chroma.

Texture

Texture has great influence on the physical-water and chemical behavior of the soil, and therefore, its evaluation is of great importance for the use and management of soils used for agriculture. It is expressed by the proportion of the granulometric components of the mineral phase of the soil, sand, silt or verdigris and clay.

It must be observed in the soil, in the morphological description, but its definitive value is given by the granulometric analysis, carried out in the laboratory.

Structure

It is the arrangement established by the union of primary soil particles together by various substances found in the soil, such as organic matter, iron and aluminum oxides , carbonates, silica, etc.

This arrangement gives rise to aggregates, which are structural units separated from each other by surfaces. The structure has a great influence on the development of plants in the soil, such as the root system, storage and availability of water and nutrients, and resistance to erosion.

The structure is characterized according to three aspects:

  • Type: lamellar, prismatic, columnar, angular blocks, subangular blocks, granular.
  • Size: very small, small, medium, large, very large.
  • Degree of development: weak, moderate, strong.

Consistency

Consistency differentiates the adhesion and cohesion of soil particles, which can vary depending on texture, organic matter and mineralogy and must be observed in the soil under three humidity conditions:

Dry consistency: evaluates the degree of resistance to breakage or detachment of the clod. It is classified as loose, soft, slightly hard, hard, very hard, extremely hard.

Wet consistency: it is given by the friability of slightly moist soil. It is classified as loose, friable, very friable, firm, very firm, extremely firm.

Wet consistency: observed in wet, kneaded and homogenized samples in hands. Plasticity (ability of the material to be molded) is evaluated in three types: non-plastic, slightly plastic and very plastic; tackiness (adhesion capacity), in three types: non-sticky, slightly sticky and very sticky.

Porosity

Porosity is displayed on the soil profile and should be described by the number and size of the pores.

  • Quantity: few, many.
  • Size: small, medium, large or very large.

Waxiness

Waxyness can be seen in the soil with the naked eye or with the help of a magnifying glass on the surface of the aggregates or in the laboratory, through micromorphological analysis. It occurs on the surfaces of the aggregates or in the pores. It has a shiny or smooth appearance, resulting from the deposition of inorganic material or clay. The classification is done according to two aspects:

  • Degree of development: weak, moderate or strong.
  • Quantity: little or abundant.

Mineral nodules and concretions

They are cemented bodies that are different from the soil matrix and can stand out from it. Nodules have no internal organization. The concretions develop around a point, concentrically. In the description of the soil, various aspects of the nodules or concretions must be considered, such as quantity, size, hardness, shape, color and nature.

Magnetic minerals: soil is evaluated by the degree of magnetic attraction to a pocket magnet.

Carbonates: it is detected in the soil by the degree of effervescence of the surface of the material when it comes into contact with a small volume of 10% hydrochloric acid.

Manganese: It is detected in the soil by the degree of effervescence of the surface of the material when it comes into contact with a small volume of 20 volume hydrogen peroxide.

mangrove areas or areas with drainage restriction. In the soil, sulfide compounds have a golden-yellow color and characteristic odor.

Efflorescence

They are observed in the soil as salt crusts on the surfaces of structures. They are the result of the accumulation of salts after evaporation, which is why they are found in dry soil conditions.

Cohesion

It is a characteristic related to the hardness (hard, very hard or extremely hard) of subsurface horizons when dry and friability (friable to firm) when wet. Two degrees of cohesion in the field can be described:

Moderately cohesive: material resistant to penetration by knife, geological hammer and shovel. Hard consistency when dry and friable to firm when wet.

Strongly Cohesive: The material strongly resists penetration by knife, geologist’s hammer and shovel. Its consistency is very hard to extremely hard when dry and friable to firm when wet.

Types of soils

Among the factors that contribute to the characterization of the soil are climate, solar incidence, the rock that originated the soil, organic matter, plant cover, etc. The soil can be classified as sandy, clayey, smokey and calcareous.

Sandy ground

It has a large amount of sand. This type of soil is very permeable, since water easily filters through the spaces formed between the grains of sand. It is usually poor in nutrients.

Clay floor

It is made up of small and compact grains, being waterproof and presenting a large amount of nutrients, an essential characteristic for the practice of agricultural activity.

smoky ground

Called in some places black earth, this type of soil is quite fertile, as it contains a high concentration of decomposing organic material. The humid soil is very suitable for carrying out agricultural activity.

calcareous soil

With little nutrients and a large amount of rock particles in its composition, calcareous soil is unsuitable for growing plants. It is typical of desert regions .

Related Posts