What Determines the Texture of Soil?

The GardenSpring |

Soil texture is a common factor in determining your soil’s water-absorbing abilities. There are many different types of soil textures, but one of the most prominent ones that we can use to tell how good of a water absorber your soil is: those with sand, silt, and clay content are known as loams.

What Is Soil Texture?

Soil texture determines the percentage of components of the mineral part of the soil, namely sand, silt, and clay, which is determined according to the percentage of each component, soil texture class.

In fact, soil texture is an indicator to determine the relative content of mineral particles that make up the soil

Therefore, by measuring the three main components of soil (sand-silt and clay), the type of soil texture can be understood.

What Determines the Texture of Soil?
Photo by Rachel Claire from Pexels

Components of Soil Texture

1- Sand: Sand is the largest mineral component of soil with a diameter of between 2 mm and 50 microns. Water holding capacity in the sand is very low and its permeability is high.

Sand has low adhesion and formability and has high roughness and abrasion properties. Sandy soils have large coarse pores and small pores and their specific gravity is high.

Sandy soils dry and heat faster than other soils and are easier to plow. The roots also move more easily in the sand. They have good air conditioning but are poor in food.

2- Silt: In terms of particle diameter, silt is the interface between sand and clay and their diameter is between 2 microns to 50 microns.

Silt is malleable but does not form as a strip or wick like clay, so silt is less malleable than clay and cracks form when we wick it.

In terms of permeability, water retention, adhesion, and slip are intermediate between sand and clay. Silt is not inflammable and soils whose texture is silt do not crack after irrigation and have good leveling properties.

It can also be said that silt texture has more water retention capacity than sand texture but is poor in nutrients compared to clay texture.

3- Clay: Clay is the smallest component of soil. its particle diameter is less than 2 microns. In clay soils, after irrigation and drying, sometimes deep and wide cracks are formed in these soils.

which are very unsuitable for growing the plant and cause the seed germ to break. The clays also have high adhesion properties and do not crack or break even when we turn them into wicks or strips after wetting them.

They have high water-holding power and their permeability is zero or very low. Also, compared to other soils, they dry late and are difficult to plow, but are rich in nutrients.

Clay is structurally divided into two categories: 1: 1 and 2: 1, which are completely different in terms of makeup system and characteristics.

Soil Texture Measurement Methods

 Determining the Texture Based on Its Touch (Qualitative Method)

In this method, water is added to the soil sample to form a paste, then the paste is rubbed in the palm of the hand to form a wire. The wire is moved forward between the index finger and thumb to create a fracture at one point on the wire.

Measure the length of the broken tape.

If the length of the broken strip is less than 3 cm, the texture of the soil is sandy.

If the length of the broken strip is between 3-5 cm, the soil texture is silt.

If the length of the broken strip is more than 5 cm, the texture of the soil is Russian.

This method is usually used in the field to estimate the soil texture and where there are no laboratory facilities, and if it is necessary to accurately identify the soil, after selecting the sample and transfer to the laboratory, more accurate methods are used to determine the soil texture.

 Screening Method

In this method, sieves are used which are stacked in order of coarseness and small diameter of their holes, and at the end of the sieves, a container is placed in which particles smaller than the diameter of the last sieve hole are placed in that container.

The sieve is poured and the sieves, which sometimes number up to ten, are connected to the shaker (shaker). With the shocks that the shaker gives to the sieve, different soil components are placed in different sieves according to their diameter. Percentage of them find out.

Particles smaller than the last sieve, which is about 80 microns, accumulate inside the last container and the percentage of fine particles is determined. This method is mostly used to determine the percentage of sand components.

In this method, determining the texture of the soil is not accurate because the soil organic matter is not removed and a small part of the soil gets stuck in the diagonal holes of the sieve holes, and eventually, a decrease in soil weight occurs. And most importantly, the fine components (clay and silt) can not be separated.

Photo by Lisa Fotios from Pexels

Soil Texture Triangle

In this method, an equilateral triangle is drawn, each side of which corresponds to the three main elements of each soil, namely sand, silt, and clay.

After determining the number of particles on the sides of the triangle, draw lines parallel to the sides, so that they intersect at one point. The point of intersection is in the range where the soil type can be distinguished from the soil texture triangle.

This method is also known as deposition or mechanical decomposition.

Determination of Soil Texture by Hydrometer Method (Quantitative)

The concentration of particles in liquids can be determined by a densitometer or hydrometer. In soil science, a 152H-62 hydrometer is used to determine soil texture.

The hydrometric method is similar to the pipette method. It is based on measuring the density of soil and water suspension, which gradually decreases due to sedimentation of the material and the hydrometer sinks deeper into the liquid.

Determine Soil Texture With Software

Free texture Autolookup or TAl is used to determine soil texture, which is a good alternative to soil triangle.

Features of this application can be

It’s free

Low volume and easy installation

Quick and very accurate detection of soil texture

Easy performance

Cited.

Types of Soil Texture

With each of the above methods, the best and most accurate of which is the software method, the type of soil texture can be determined.

Dry Soil Texture
Photo by Francesco Ungaro from Pexels

The name of the soil texture depends on the amount and effect of each group of “sand”, “silt” and “clay” particles.

1- Sand: The minimum amount of sand is 85% and the total and 1.5 times the clay particles is less than 15%.

2- Loamy sand: sand between 70 to 90% and the total silt and 1.5 times the clay particles is more than 15% and the amount of clay is less than 30%.

3- Sandy loam: Clay is less than 20% or total% silt and twice the amount of clay is more than 30%. Soils with a sand content of 24 to 52%, clay content of less than 7%, and silt content of less than 50% are called loamy and sandy soils.

4- Loam The amount of clay is between 7 to 27%, silt is 28 to 50% and sand is less than 52%.

5- Silt loam: The amount of silt is more than 50% and the amount of clay is between 12 to 27% or the amount of silt fluctuates between 50 to 80% and the amount of clay is less than 12%.

6- Silt The amount of silt is less than 80% and the amount of clay is less than 12%.

7- sandy clay loam: It has 20 to 35% clay and its silt content is 28% less and its sand is more than 45%.

8- Clay loam The amount of clay fluctuates up to 27 to 40% and the amount of loam is less than 20% to 45%.

9- Silty clay loam The amount of clay is 27 to 40% and the amount of sand is less than 20%.

10 – Clay and sand (sandy clay) The amount of clay and sand is more than 35 to 45%.

11- Clay and silty clay The amount of each clay and silt is more than 40%, respectively.

12- Clay The amount of clay is more than 40% and the amount of sand and silt is less than 45 to 40%, respectively.

Is It Possible to Change the Soil Texture?

In answer to this question, it should be said that although it is almost impossible to change the soil texture on a large scale, in a certain range, when the soil texture is very heavy and clayey, soil texture can be changed by adding livestock and straw manure and green manures.

Conclusion

Identifying the type of soil texture of gardens, orchards, and fields, as well as modifying its texture if necessary; It will play an important role in increasing the production of quality products, reducing irrigation and production costs, increasing productivity and profitability. 

Therefore, it is necessary to determine the type of soil in your farm before choosing the method of pressurized irrigation (sprinkler or drip). With the full advertisement of the best irrigation method, suitable for your farms to be selected.

Citation

Queensland;, C. O. S. O. (2013, September 24). Soil texture. Environment, Land and Water | Queensland Government. https://www.qld.gov.au/environment/land/management/soil/soil-properties/texture#:%7E:text=Soil%20texture%20(such%20as%20loam,made%20up%20largely%20of%20clay.

Leave a Comment