Understanding Soil Texture and Structure. What is soil texture and why is it important? Soil texture...
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Transcript of Understanding Soil Texture and Structure. What is soil texture and why is it important? Soil texture...
![Page 1: Understanding Soil Texture and Structure. What is soil texture and why is it important? Soil texture is the fineness or coarseness of a soil. It describes.](https://reader035.fdocuments.in/reader035/viewer/2022062217/56649eef5503460f94bff443/html5/thumbnails/1.jpg)
Understanding Soil Texture and Structure
![Page 2: Understanding Soil Texture and Structure. What is soil texture and why is it important? Soil texture is the fineness or coarseness of a soil. It describes.](https://reader035.fdocuments.in/reader035/viewer/2022062217/56649eef5503460f94bff443/html5/thumbnails/2.jpg)
What is soil texture and why is it important?
• Soil texture is the fineness or coarseness of a soil.
• It describes the proportion of three sizes of soil particles. These are:–Sand - large particle
–Silt - medium sized particle
–Clay - small particle
![Page 3: Understanding Soil Texture and Structure. What is soil texture and why is it important? Soil texture is the fineness or coarseness of a soil. It describes.](https://reader035.fdocuments.in/reader035/viewer/2022062217/56649eef5503460f94bff443/html5/thumbnails/3.jpg)
![Page 4: Understanding Soil Texture and Structure. What is soil texture and why is it important? Soil texture is the fineness or coarseness of a soil. It describes.](https://reader035.fdocuments.in/reader035/viewer/2022062217/56649eef5503460f94bff443/html5/thumbnails/4.jpg)
Texture is important because it affects:
i. Water-holding capacity the ability of a soil to retain water for use by plants
ii. Permeability the ease with which air and water may pass through the soil.
![Page 5: Understanding Soil Texture and Structure. What is soil texture and why is it important? Soil texture is the fineness or coarseness of a soil. It describes.](https://reader035.fdocuments.in/reader035/viewer/2022062217/56649eef5503460f94bff443/html5/thumbnails/5.jpg)
Texture is important because it affects:
iii. Soil workability the ease with which soil may be tilled
iv. Ability of plants to grow some root crops like carrots and onions
• Root crops will have difficulty growing in a fine-textured soil
![Page 6: Understanding Soil Texture and Structure. What is soil texture and why is it important? Soil texture is the fineness or coarseness of a soil. It describes.](https://reader035.fdocuments.in/reader035/viewer/2022062217/56649eef5503460f94bff443/html5/thumbnails/6.jpg)
How is the texture of soil determined?
• Soil texture may be determined in one of two ways:–The percentages of sand, silt, and
clay may be tested in the lab. • Once tested, you may determine the
textural class of the soil by referring to the textural triangle.
![Page 7: Understanding Soil Texture and Structure. What is soil texture and why is it important? Soil texture is the fineness or coarseness of a soil. It describes.](https://reader035.fdocuments.in/reader035/viewer/2022062217/56649eef5503460f94bff443/html5/thumbnails/7.jpg)
![Page 8: Understanding Soil Texture and Structure. What is soil texture and why is it important? Soil texture is the fineness or coarseness of a soil. It describes.](https://reader035.fdocuments.in/reader035/viewer/2022062217/56649eef5503460f94bff443/html5/thumbnails/8.jpg)
Textural Triangle – 12 basic textural classes
• Silt
• Silt loam
• Silty clay loam
• Loam
• Sandy clay loam
• Loamy sand
• Sand
• Sandy loam
• Sandy clay
• Clay loam
• Silty clay
• Clay
![Page 9: Understanding Soil Texture and Structure. What is soil texture and why is it important? Soil texture is the fineness or coarseness of a soil. It describes.](https://reader035.fdocuments.in/reader035/viewer/2022062217/56649eef5503460f94bff443/html5/thumbnails/9.jpg)
Example 1:
10% clay
20% silt
70% sand
This soil would be called
sandy loam
![Page 10: Understanding Soil Texture and Structure. What is soil texture and why is it important? Soil texture is the fineness or coarseness of a soil. It describes.](https://reader035.fdocuments.in/reader035/viewer/2022062217/56649eef5503460f94bff443/html5/thumbnails/10.jpg)
Example 2:
30% clay
20% silt
50% sand
This soil would be called
sandy clay loam
![Page 11: Understanding Soil Texture and Structure. What is soil texture and why is it important? Soil texture is the fineness or coarseness of a soil. It describes.](https://reader035.fdocuments.in/reader035/viewer/2022062217/56649eef5503460f94bff443/html5/thumbnails/11.jpg)
Example 3:
50% clay
45% silt
5% sand
This soil would be called Silty Clay
![Page 12: Understanding Soil Texture and Structure. What is soil texture and why is it important? Soil texture is the fineness or coarseness of a soil. It describes.](https://reader035.fdocuments.in/reader035/viewer/2022062217/56649eef5503460f94bff443/html5/thumbnails/12.jpg)
Example A:
50% clay
30% silt
20% sand
This soil would be called
![Page 13: Understanding Soil Texture and Structure. What is soil texture and why is it important? Soil texture is the fineness or coarseness of a soil. It describes.](https://reader035.fdocuments.in/reader035/viewer/2022062217/56649eef5503460f94bff443/html5/thumbnails/13.jpg)
The Ribbon Method.
• The relative amounts of sand, silt and clay may also be determined in the field using the ribbon method.
• Fine- textured a ribbon forms easily and remains long and flexible.
• Moderately fine- textured a ribbon forms but breaks into pieces ¾ to 1 inch long.
• Medium- textured no ribbon forms. – The sample breaks into pieces less than ¾ inch
long. The soil feels smooth and talc-like.
![Page 14: Understanding Soil Texture and Structure. What is soil texture and why is it important? Soil texture is the fineness or coarseness of a soil. It describes.](https://reader035.fdocuments.in/reader035/viewer/2022062217/56649eef5503460f94bff443/html5/thumbnails/14.jpg)
The Ribbon Method.
• Moderately coarse- textured no ribbon forms. –The sample feels gritty and lacks
smoothness.
• Coarse- textured no ribbon forms. –The sample is composed almost
entirely of gritty material.
![Page 15: Understanding Soil Texture and Structure. What is soil texture and why is it important? Soil texture is the fineness or coarseness of a soil. It describes.](https://reader035.fdocuments.in/reader035/viewer/2022062217/56649eef5503460f94bff443/html5/thumbnails/15.jpg)
What is soil structure, how does it form, and why is it important?
• Soil structure is the arrangement of the soil particles into clusters or aggregates of various sizes and shapes.
• Aggregates that occur naturally in the soil are referred to as peds, while clumps of soil caused by tillage are called clods.
![Page 16: Understanding Soil Texture and Structure. What is soil texture and why is it important? Soil texture is the fineness or coarseness of a soil. It describes.](https://reader035.fdocuments.in/reader035/viewer/2022062217/56649eef5503460f94bff443/html5/thumbnails/16.jpg)
What is soil structure, how does it form, and why is it important
• Structure is formed in two steps.• A clump of soil particles sticks loosely
together. These are created through:– Plant roots surrounding the soil and separating
clumps– Freezing and thawing of soil– Soil becomes wet and then dries– The soil is tilled– Fungal activity
![Page 17: Understanding Soil Texture and Structure. What is soil texture and why is it important? Soil texture is the fineness or coarseness of a soil. It describes.](https://reader035.fdocuments.in/reader035/viewer/2022062217/56649eef5503460f94bff443/html5/thumbnails/17.jpg)
What is soil structure, how does it form, and why is it important
• Weak aggregates are cemented to make them distinct and strong.
• Clay, iron oxides, and organic matter may act as cements.
• When soil microorganisms break down plant residues, they produce gums that also glue peds together.
![Page 18: Understanding Soil Texture and Structure. What is soil texture and why is it important? Soil texture is the fineness or coarseness of a soil. It describes.](https://reader035.fdocuments.in/reader035/viewer/2022062217/56649eef5503460f94bff443/html5/thumbnails/18.jpg)
What is soil structure, how does it form, and why is it important
• Soil structure is important for several reasons:–It improves soil tilth.
–It improves permeability.
–It resists the beating action of raindrops, minimizing the formation of crusts that reduce crop stands.
![Page 19: Understanding Soil Texture and Structure. What is soil texture and why is it important? Soil texture is the fineness or coarseness of a soil. It describes.](https://reader035.fdocuments.in/reader035/viewer/2022062217/56649eef5503460f94bff443/html5/thumbnails/19.jpg)
What are the various soil structures and what do they look like?
There are eight primary types of structure. They are:
• Granular— aggregates are small, non-porous, and strongly held together.
• Crumb— aggregates are small, porous, and weakly held together.
• Platy— aggregates are flat or plate-like. Plates overlap, usually causing slow permeability.
![Page 20: Understanding Soil Texture and Structure. What is soil texture and why is it important? Soil texture is the fineness or coarseness of a soil. It describes.](https://reader035.fdocuments.in/reader035/viewer/2022062217/56649eef5503460f94bff443/html5/thumbnails/20.jpg)
What are the various soil structures and what do they look like?
• Prismatic or Columnar— aggregates are prism-like. Prismatic has flat caps while columnar has rounded caps.
• Blocky— aggregates are block-like, with six or more sides. All three dimensions are about the same.
• Structureless— there is no apparent structure. It may be found in one of two forms:
– Single grain—soil particles exist as individuals and do not form aggregates.
– Massive—soil particles cling together in large uniform masses.
![Page 21: Understanding Soil Texture and Structure. What is soil texture and why is it important? Soil texture is the fineness or coarseness of a soil. It describes.](https://reader035.fdocuments.in/reader035/viewer/2022062217/56649eef5503460f94bff443/html5/thumbnails/21.jpg)