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.
Compaction destroys soil structure and causes significant plant growth problems in Utah landscapes. It is normally caused by repeated foot or vehicle traffic over the same soil area. The traffic may be associated with construction activities, or foot or vehicle traffic in established landscapes.
Soil compaction can impact the efficiency and economics of production in a number of ways, resulting in: Poor rooting and reduced crop yield and quality. Less crop uniformity. Poor drainage.
(1986) found that compacted soils resulted in: (a) restricted root growth; (b) poor root zone aeration; and (c) poor drainage that results in less soil aeration, less oxygen in the root zone, and more losses of nitrogen from denitrification. Subsoil tillage has been used to alleviate compaction problems.
Compacted soils impede root development which can reduce yields. Along with reduced plant growth, poor aeration induces the loss of soil nitrogen and produces greenhouse gases through denitrification in anaerobic sites (European Commission, 2014).
Soil compaction occurs when soil particles are pressed together, reducing pore space between them (Figure 1). Heavily compacted soils contain few large pores, less total pore volume and, consequently, a greater density. A compacted soil has a reduced rate of both water infiltration and drainage.
If the soils are not adequately compacted at the time they are placed, they will slowly settle over time due to water, gravity and overriding forces.
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.
Loss of large pores between aggregates is particularly harmful for fine- and medium-textured soils that depend on those pores for good infiltration and percolation of water, as well as air exchange with the atmosphere. Although compaction can also damage coarse-textured soils, the impact is less severe.
Soil Density
The most direct effect of soil compaction is an increase in the bulk density of soil. Bulk density is the mass of oven-dry soil in a standard volume of soil, often given as grams per cubic centimeter (g/cm3). Optimum bulk densities for soils depend on the soil texture (Table 1).
Use large root crops to break up compacted soil. Consider alfalfa, sunflowers, beets, or daikon radishes. Adding crops with bigger roots can increase water 10-100x with improved water infiltration. Plant cover crops to help retain and manage moisture.
Inadequate compaction results in a pavement with decreased stiffness, reduced fatigue life, accelerated aging/decreased durability, rutting, raveling, and moisture susceptibility (Hughes, 1984; Hughes, 1989).
Alter the Tillage Depth
If you till the soil, vary tillage depth to minimize the development of a “tillage pan” or compacted zone where the tillage implement shears the soil. Till deeper in dry years when soil fracturing is greatest. Keep tillage shallow in wet years to avoid formation of a deep tillage pan.
Explanation: When soil becomes compacted by human use, the most likely result is decreased permeability.
Mechanical compaction: The most reliable method, it uses tools like vibratory rollers, rammers, and compactors to press the soil down and remove air pockets.
Soil compaction can lead to: poor root growth—which reduces crop yield through poor water and nutrient uptake. difficulties with soil cultivation and seedbed preparation. a decrease in water entering the soil either as rain or irrigation.
Overwatering causes severe compaction of the soil, reducing its ability to retain nutrients and support healthy grass growth.
Most yield- limiting compaction is caused by wheel traffic from heavy equipment, often when operations are conducted on wet soils (the photo above shows a prime example of the destructive damage caused by heavy equipment on wet soils). Significant com- paction can also be caused by tillage and livestock.
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.
The force of raindrops mechanically compacts surface dirt, creating a soil crust that is up to ½-inch deep. This layer impedes drainage and makes it hard for seedlings to emerge from soil. By applying low-pressure water near the ground's surface, the soil compacts evenly.
Adding compost to your soil is one of the best ways to combat compaction. As organic materials decompose, they attract soil organisms that naturally aerate the soil through creation of pore space.
Compaction is the process during which the volcanic clast pore volume or volcanic rocks decreases, the density increases, the grain deformation and rupture, or even local dissolution occurs, under the action of the overburden formation pressure.
In simple terms, when we say a soil sample has achieved 95% compaction, it means that the compacted soil has reached 95% of its maximum possible dry density as determined by a Proctor test. Proctor testing is a test performed in the laboratory that compares the density of a soil sample to various moisture contents.