One of the most important characteristics to know about your soil, texture is simply the relative amounts of different-size mineral particles present. Soils contain a mix of different particle sizes and are described Dy the particle size that dominates their particular mix. While some people call sandy silty, or clayey their soil type, they're really describing its texture.
Texture has a major effect on the physical properties of soil. As particle sizes get larger, the spaces between particles get larger, too. This explains why sandy soils drain more quickly than other soils. The smaller the particles, the more surface area they provide for holding water and nutrients. This is why soils containing more clay have a greater ability to hold nutrients and moisture.
As you might guess, there's a trade-off in the advantages offered by different textures. Too much clay results in a soil with plenty of nutrients but problems from poor aeration and slow drainage. Such soils are described as heavy. Too much silt can also cause drainage problems. Too much sand means there's never a drainage problem, but you have to keep adding fertilizer, as most washes away. Such soils are described as light.
The best soil texture isn't made up of all medium-size particles but of a balanced mix of sizes. Loam is the technical word used to describe this ideal texture; such soils are the best ones for gardening and farming.
Loams are usually subdivided into sandy loams, clay loams, silt loams, and even silty clay loams.
DID YOU KNOW?
The surface of soil par tic., where much of the water nutrient reserves are held. It-where many important chemical reactions take place. Think of tide surfaces as tiny magnet* More surface area means a gn ability to hold water and nutrient where plants can get them.
Fine clay can provide 10,01 times more surface area than same weight of medium-size grains; 1,(0) times more surj area than silt. A pound of pure clay provides up to 90 acres of face area!
The finest soil particles, those smaller than 0001 inch and too small to see, are the day particles Nex largest are silt particles, larger than clay but smaller than .002 inch and still tea small Ze ore cay or silt feels mastly smooth between yOUr angers Son, particles range in size from 002 o •08 .nc . They re usually large enough to see ond feel gritty between your fingers An 1 larger than sand is considered gravel^ ^
Common Characteristics of Soils with Different Textures
High Silt Content
Harder to cultivate when moist or wet
()ften very dusty when dry
Rarely forms clods
Somewhat slow to warm up in spring
Moderate to high levels of organic matter
Organic matter breaks down somewhat quickly
Hard to correct soil acidity or alkalinity
High risk of erosion in windy areas
High risk of erosion by water
Feels silky between fingers (any grittiness is very fine)
High Clay Content
I >o not cultivate when w»-t and sticky (high risk of compaction)
1 lard or cementlike when dry
Slow to warm up in spring
High to moderate levels of organic matter
Organic matter breaks down slowly
Hard to correct soil acidity or alkalinity (but once corrected, effects last)
Low risk of erosion in windy areas
There's a simple fix for soils with less-than-ideal textures: Add organic matter. Lots of organic matter makes soils of any texture behave more like an ideal loam. While adding pure clay to sand will improve its texture, in practice that's hard to do. It's easier to buy coarse sand to add to clay, but it's really hard to add enough to improve drainage. Organic matter is much easier to add — and more effective. Abundant amounts of organic matter increase the ability of sandy soils to stay moist and retain nutrients. Magically, they also improve the aeration and drainage of clay soils. Chapters 4 and 5 explain many ways to increase your soil's organic matter.
Extreme textures may need more than organic matter. Clay soils must be handled carefully and often benefit from double-digging. Building a raised bed may be required where drainage problems are severe. Careful plant choice will help you in very sandy soils — or any other extreme soil. Chapter 7 explains techniques and plants for soils with problem textures.
How Texture Affects Soil Properties
Ease of Water Infiltration medium poor medium good
Ability to Hold Nutrients medium excellent medium very poor
Water-Holding Capacity medium good medium very poor
Ease of Working medium poor medium good
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