What is a dispersive soil?
In a dispersive soil, the soil aggregates (small clods) collapse when the soil gets wet by fresh water, because the individual clay particles disperse into solution. This collapse of structure causes the soil to slump, lose porosity and become denser, thus restricting root growth of most plants.
How do you treat dispersive soil?
Managing dispersive (sodic) soils
- Avoid disturbing already productive sodic soils.
- Apply lime or gypsum.
- Increase organic matter.
- Use deep-ripping.
- Use raised beds or deepened seedbeds.
- Use alternative plant and land-use options.
What makes soil dispersive?
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.
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 slaking?
Slaking is the breakdown of a lump of soil into smaller fragments on wetting. It is caused when clay swells and the trapped air bursts out. Organic matter reduces slaking by binding mineral particles and by slowing the rate of wetting.
What is the meaning of dispersive?
tending to disperse
1 : of or relating to dispersion a dispersive medium the dispersive power of a lens. 2 : tending to disperse. Other Words from dispersive. dispersiveness noun.
What causes soil Sodicity?
Sodicity is caused by the presence of sodium attached to clay in soil. A soil is considered sodic when the sodium reaches a concentration where it starts to affect soil structure. The sodium weakens the bonds between soil particles when wetted resulting in the clay swelling and often becoming detached.
Are sandy soils dispersive?
Dispersive soils in Western Australia The agricultural soil types most commonly affected by sodicity in Western Australia are the clays both cracking and non-cracking, calcareous loamy earths and sandy and loamy duplex soils. In duplex soils the fine-textured clay B horizon (subsoil) is often sodic.
Are all clays dispersive?
To explain dispersion, it is easiest to begin with a simple animation of two dry aggregates of soil dispersing when placed in water. Clays particles are small in size (less than 0.002 mm) but have a very large surface area. The surface area of all clays is negatively charged.
What causes slaking in soil?
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 a dispersive material?
When the speed of light in a material is a function of frequency, the material is said to be dispersive. When the permittivity or permeability of a material are functions of frequency, the material is dispersive.
What are dispersive soils?
Dispersive soils are common in the agricultural areas of Western Australia, where they occur mainly as duplex or gradational profiles. Soils with more than about 18% sodic clay are susceptible to dispersion when wet.
What type of soil does Western Australia have?
Dispersive (sodic) soils in Western Australia. Dispersive soils are common in the agricultural area of Western Australia, where they occur mainly as duplex or gradational profiles. Soils with more than about 18% clay, and that clay being sodic, are susceptible to dispersion when wet.
What is meant by soil dispersion after remoulding?
Dispersion of soil slows down the intake of water to the root zone following rainfall or irrigation. This condition will result in poor water storage at each irrigation. Dispersion after remoulding means that, under wet conditions, the soil is likely to disperse after cultivation.
What influences clay dispersion?
Chorom M, Rengasamay P and Murray RS (1994). Clay Dispersion as Influenced by pH and Net Particle Charge of Sodic Soils. Australian Journal of Soil Research.