- Author: Ben Faber
Why is soil texture important?
Soil texture is one of the most important properties to know how to measure, as it affects many other chemical, physical, and biological soil processes and properties such as the available water-holding capacity, water movement though the soil, soil strength, how easily pollutants can leach into groundwater, and the natural soil fertility. Follow the Soil Texture Pathway to figure out a given soil's texture: Estimating Soil Texture by Feel
By knowing the texture of the soil and the depth of topsoil, a producer can estimate the amount of water available to produce a crop. If the soil texture is sand, then it can hold between 0.5 and 1.0 inch of water per foot of soil depth. If a producer had four foot of topsoil, there is 2 to 4 inches of water available for the crops use. If the soil texture is sandy loam, there is 1.0 to 1.5 inches of available water per foot of topsoil. If the soil texture is silt or a clay loam, there is 1.5 to 2.0 inches of available water per foot of topsoil. If the soil texture is clay, there is 2.0 to 2.5 inches of available water per foot of topsoil.
Degree of Soil Moisture | Percent Useful Soil Moisture Remaining | Feel or Appearance of Soils | |||
---|---|---|---|---|---|
Coarse (Sand) | Light (Sandy Loams) | Medium (Silt and Clay Loams) | Heavy (Clay) | ||
Dry |
0 |
Dry, loose, single-grained, flows through fingers. |
Dry, loose, flows through fingers. |
Powdery, dry, sometimes slightly crusted but easily breaks down into powdery condition. |
Hard, baked, cracked; sometimes has loose crumbs on surface. |
Low |
50% or less |
Still appears to be dry; will not form a ball with pressure.* |
Still appears to be dry; will not form a ball.* |
Somewhat crumbly, but will hold together from pressure.* |
Somewhat pliable; will ball under pressure.* |
Fair |
50 to 75% |
Still appears to be dry; will not form a ball with pressure.* |
Tends to ball under pressure but seldom will hold together. |
Forms a ball, somewhat plastic; will sometimes slick slightly with pressure. |
Forms a ball; will ribbon out between thumb and forefinger. |
Excellent |
75% to
|
Tends to stick together slightly; sometimes forms a very weak ball under pressure. |
Forms weak ball, breaks easily, will not slick. |
Forms a ball and is very pliable; slicks readily if relatively high in clay. |
Easily ribbons out between fingers, has a slick feeling. |
Ideal |
At field
|
Upon squeezing, no free water appears on soil but wet outline of ball is left on hand. |
Upon squeezing, no free water appears on soil but wet outline of ball is left on hand. |
Upon squeezing, no free water appears on soil but wet outline of ball is left on hand. |
Upon squeezing, no free water appears on soil but wet outline of ball is left on hand. |
Too Wet |
Above field
|
Free water appears when soil is bounced in hand. |
Free water will be released with kneading. |
Can squeeze out free water. |
Puddles and free water forms on surface. |
Now figure out the soil moisture holding capacity of your soil by feeling it again with the USDA Picture Guidelines
https://www.wcc.nrcs.usda.gov/ftpref/wntsc/waterMgt/irrigation/EstimatingSoilMoisture.pdf
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- Author: Dr. Anthony Fulford
What is subsoil?
There are several layers (also known as “horizons” to soil scientists) that can be found when we dig deeper and deeper down into the soil. We can imagine all the individual layers of a soil stacked one on top of the other like a layer cake, this is called the soil profile. The surface soil is the uppermost layer of the soil profile, and the one we are most familiar with, because this is where most of the action takes place. Soil mixing with tillage, compost and fertilizer application, irrigation, plant root growth, and animal activity (including microbes) are mainly concentrated within the soil's surface layer. Additionally, decomposition of plant and leaf litter occurs most rapidly in the surface soil, this eventually leads to the formation of new soil organic matter. In comparison, the subsurface soil, or subsoil, is composed of one or more soil layers that lie below the influence of surface soil activities. There is not a consistent depth at which every surface soil layer changes into the subsoil layer(s), rather the subsoil occurs at a different depth from place to place depending on numerous factors, including some of the factors mentioned previously. This is the reason why it is difficult to determine where the subsoil layer begins in the soil profile.
What does subsoil contain?
What does subsoil look like?
What is subsoil used for?
In general, the subsoil is a less suitable medium for plant growth compared to surface soil because of some of the factors mentioned previously. There are properties of subsoil however that make it suitable for other uses such as a source of “fill soil” for “cut-and-fill” construction operations, as a source of clay for building materials, and as an absorption layer for on-site wastewater disposal.
What can home gardeners do to keep their subsoil in great shape year after year?
What is the substratum layer of soil? Does that layer affect gardening at all, and if so how?
What is the bedrock layer? Does that layer affect gardening at all, and if so how?
Bedrock is the bottom layer of the soil profile layer cake. The bedrock layer consists of solid rock that has not yet been exposed to the chemical, physical, and biological processes of the surface soil and subsoil. In some places, bedrock is the foundation from which the overlying soil layers developed, while in other places, the bedrock layer may have become “buried” by windblown sand or sediment. Bedrock does not directly influence plant growth, but it can determine the type of clay minerals found in different layers of the soil profile.
Dr. Anthony Fulford is the Area Nutrient Management and Soil Quality Advisor for Stanislaus, Merced, and San Joaquin Counties.
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