Soil compaction causes a decrease in large pores (called macropores), resulting in a much lower water infiltration rate into soil, as well as a decrease in saturated hydraulic conductivity.
Explanation: When soil becomes compacted by human use, the most likely result is decreased permeability.
A compacted soil has a reduced rate of both water infiltration and drainage. This happens because large pores more effectively move water downward through the soil than smaller pores. In addition, the exchange of gases slows down in compacted soils, causing an increase in the likelihood of aeration-related problems.
While a number of factors contribute to compaction, such as farm machinery weight and traffic, rain, and tillage, it is fundamentally a biological problem caused by a lack of actively growing plants and active roots in the soil.
Compaction is a major problem that inhibits the growth of plant roots which affects the health of crops, pastures, and landscape vegetation. Plant roots are unable to penetrate the soil as it becomes denser and little root growth occurs, except if there are cracks in the soil that can be followed by plant roots.
Soil compaction increases soil density, reduces porosity (especially macroporosity), and leads to increased penetration resistance and a degradation of soil structure. This degradation is enforced when tillage is used to break up compacted soils.
Compaction increases the shear strength of soils by adding friction from the interlocking of particles. Future settlement of soils is reduced by increasing the stiffness and eliminating voids creating a densified soil.
Half of the topsoil on the planet has been lost in the last 150 years. In addition to erosion, soil quality is affected by other aspects of agriculture. These impacts include compaction, loss of soil structure, nutrient degradation, and soil salinity. These are very real and at times severe issues.
The shaping of the human embryo begins with compaction, during which cells come into close contact and form a tighter structure1,2. Assisted reproductive technology (ART) studies suggest that human embryos fail compaction primarily because of defective adhesion3,4.
Factors affecting compaction
A number of factors will affect the degree of compaction that can be achieved: Nature and type of soil, i.e. sand or clay, grading, plasticity. Water content at the time of compaction. Site conditions, e.g. weather, type of site, layer thickness.
In geotechnical engineering, soil compaction is the process in which stress applied to a soil causes densification as air is displaced from the pores between the soil grains.
What Causes Soil Salinization? Soil salinization occurs when soluble salts are retained in the earth. It happens either naturally or because of improper anthropogenic activities, particularly farming practices. Besides, some earths are initially saline due to low salt dissolution and removal.
There are not enough pores or spaces in compacted soil to allow unrestricted root movement, infiltration, drainage or air circulation. The restricted roots are often unable to take up sufficient water or nutrients from the soil. The result is less plant growth and lower yields, particularly during periods of drought.
Compaction occurs when pore spaces are reduced to the point that air and water cannot move freely and plant roots cannot grow easily into the surrounding soil. The soil could remain overly wet longer than is healthy for the plants growing there.
Soil erosion is more likely where the ground has been disturbed by agriculture, grazing animals, logging, mining, construction, and recreational activities.
Wheel traffic or pressure (weight per unit area) exerted on the soil surface by large animals, vehicles, and people can cause soil compaction.
It is often caused by the removal, storage and reinstatement of soil materials during mineral extraction or mining activities, but may also exist on former industrial areas where areas of hard standing have been removed, or where the ground has been subjected to heavy machinery traffic.
The initiation of compaction primarily occurs at the third mitotic division or later in human embryos. Embryos that initiate compaction before the 8-cell stage are usually associated with aberrant embryonic development (i.e., cytokinetic failure accompanied by karyokinesis).
Compaction restricts root growth and reduces infiltration of water into soil. It can increase runoff, which may lead to greater flooding, increased erosion, and the transfer of potential pollutants (including nutrients and pesticides) to surface waters.
Aside from desertification, there is no doubt that human activities are a major cause of soil erosion in general. Construction of roads and buildings, logging, mining, and agricultural production have resulted in large amounts of soil erosion in the U.S. and around the world.
Certain agricultural land use practices, such as overgrazing, land conversion, fertilization, and the use of agricultural chemicals, can enhance the growth of invasive plants. These plants can alter fish and wildlife habitat, contribute to decreases in biodiversity, and create health risks to livestock and humans.
What causes erosion? Soil erosion occurs primarily when dirt is left exposed to strong winds, hard rains, and flowing water. In some cases, human activities, especially farming and land clearing, leave soil vulnerable to erosion.
The degree of compaction is quantified by measuring the change of the soil's dry unit weight, γd. Within the framework of engineering applications, compaction is particularly useful as it results in: An increase in strength of soils. A decrease in compressibility of soils.
Soil compaction increases soil strength and decreases soil physical fertility through decreasing storage and supply of water and nutrients, which leads to additional fertiliser requirement and increasing production cost.