What is dispersive clay soil?

What is dispersive clay soil?

Dispersive clay soils are those with unique properties which under certain conditions deflocculate and are rapidly eroded and carried away by waterflow. For dispersive clay soils to erode, a concentrated leakage channel such as a crack (even a very small crack) must exist through an earth embankment.

What causes dispersive soils?

Dispersive soils occur when soil aggregates collapse as individual clay particles disperse into solution when the soil gets wet by fresh water. This collapse of the soil structure causes the soil to slump and lose porosity. Soil dispersion in the surface soil leads to crusting and surface sealing.

How can you tell if soil is dispersive?

There are 3 ways to identify dispersive soils:

1. measure the exchangeable sodium percentage (ESP) as part of a standard soil test (measures sodicity)
2. use a simple soil dispersion test.
3. observe visual indicators of moderate or severely dispersive topsoils.

How is dispersive soil treated?

Managing dispersive (sodic) soils

1. Avoid disturbing already productive sodic soils.
2. Apply lime or gypsum.
3. Increase organic matter.
4. Use deep-ripping.
5. Use raised beds or deepened seedbeds.
6. Use alternative plant and land-use options.

What is dispersion test?

The Poisson dispersion test is one of the most common tests to determine if a univariate data set follows a Poisson distribution. The Poisson dispersion test statistic is defined as: D = \sum_{i=1}^{N}{\frac{(X_{i} – \bar{X})^2} {\bar{X}}} with \bar{X} and N denoting the sample mean and the sample size, respectively.

Which element leads to dispersion of clay particles in soils?

Dispersion is a process that occurs in soils that are particularly vulnerable to erosion by water. In soil layers where clays are saturated with sodium ions (“sodic soils”), soil can break down very easily into fine particles and wash away.

What is the meaning of dispersive?

1 : of or relating to dispersion a dispersive medium the dispersive power of a lens. 2 : tending to disperse. Other Words from dispersive More Example Sentences Learn More About dispersive.

What causes slaking?

Slaking is the breakdown of large, air-dry soil aggregates (>2-5 mm) into smaller sized microaggregates (<0.25 mm) when they are suddenly immersed in water. Slaking occurs when aggregates are not strong enough to withstand internal stresses caused by rapid water uptake.

What is Flocculated clay?

flocculation A process in which clay and other soil particles adhere to form larger groupings or aggregates, thereby coarsening the soil texture and making heavier soils easier to cultivate. The reverse of this process is known as dispersion.

What causes Sodicity?

Sodicity is caused by the presence of sodium attached to clay in soil. The sodium weakens the bonds between soil particles when wetted resulting in the clay swelling and often becoming detached. When this happens the clay particles spread out or disperse making the soil water cloudy.

What is sodic clay?

Sodicity in soil is the presence of a high proportion of sodium ions relative to other cations. As sodium salts are leached through the soil, some sodium remains bound to clay particles—displacing other cations. Soils are often considered sodic when the amount of sodium impacts soil structure.

What do you mean of dispersion?

Dispersion is the state of getting dispersed or spread. Statistical dispersion means the extent to which a numerical data is likely to vary about an average value. In other words, dispersion helps to understand the distribution of the data.

What is dispersive clay and how does it react?

Dispersive clays have an imbalance in the electrochemical forces between particles. This imbalance causes the minute soil particles in a dispersive clay to be repulsed rather than attracted to one another. Consequently, dispersive clay particles tend to react as single-grained particles and not as an aggregated mass of particles.

Is dispersive clay an impervious material in embankments?

Use of dispersive clays as an impervious material in embankments and dams can cause serious problems of internal erosion (piping) and failure induced by these problems. In this paper, impervious material areas

What are the engineering problems associated with dispersive clay soil?

4-WI-54 ENGINEERING PROBLEMS ASSOCIATED WITH DISPERSIVE SOILS Dispersive clay soils have contributed to the failure of many conservation practices. These problems range from the complete breaching of embankment, to severe erosion of earth fills and excavations. The problems may be placed into two broad categories.

What type of water erodes dispersive clay most easily?

Dispersive clays are most easily eroded by water that is low in ion concentration, such as rain water. Runoff water has the opportunity to attain ions from land surface contact making it more in ionic balance with the dispersive clays and less erosive.