Soil Types

by Stephanie Suesan Smith on October 21, 2010

Sometimes gardeners forget that not everyone speaks our language.  We talk about sandy loam soil, clay soil, sand, and silt as if everyone knew exactly what those were.  Well, not all gardeners know, and nongardeners, or beginners, certainly do not know all the terms for soil.  I can help with that.  First, the terms:

soil texture triangle

soil texture triangle

About ninty percent of soil is made up of rock of different sizes.  These sizes are sand, silt, and clay.  About ten percent of soil is made up of organic matter.  This is what supports life.  The rock determines how the soil drains water, how much air is in the soil, and how easy it is to dig.

Clay contains the smallest particles.  They hug each other close and do not easily let water or air through.  On the plus side, clay holds in nutrients and water.  Plants can drown, though, because the water pools and air cannot get in to the roots.  In hot climates, the clay may bake and become cement, killing the plants.

Silt is a particle between sand and clay.  It drains well but holds nutrients better than sand.  Pure silt is very rare, but is also very fertile.  Rivers deposit silt when they flood the bottom lands, which is one of the reasons those lands are so fertile.

Sand is the largest particle in soil.  It drains well and has lots of spaces between it for air.  The down side is that it drains too well and nutrients and water just run through, leaving plants thirst and starved for nutrients.

The ideal soil is a balance of sand, silt, and clay.  It is called sandy loam and is the Holy Grail of soil.  This drains properly, but not too well.  It holds nutrients and allows air to circulate.  It is usually found near rivers, or where rivers used to be.  Not too many people are blessed to have this type of soil.

Fret not, however.  Soil can be improved by the addition of organic matter.  This is why compost is added — to make clay soils drain better and to help sand hold moisture.  Compost adds nutrients and helps add air pockets in clay soils.  You may not be blessed with sandy loam, but you can improve your soil and grow wonderful vegetables with a little work.

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{ 3 comments… read them below or add one }

ipad Accessories October 22, 2010 at 5:10 am

Yes, very ture. Since ten year of gardening at my farm house, but frankly this such information on soil I never know. I just love it ….. well I don’t have any doubt about your articles… your posts are awesome… Honestly you are simply the best. Thanks for sharing this in your post with us.


louis vuitton wallets October 22, 2010 at 8:03 am

Mostly peoples are not know that seventy percent of soil is made up of rock of different sizes. The type of soil varies from place to place on our planet and can even vary from one place to another in your own backyard.


Perfect Grass October 22, 2010 at 1:04 pm

This is a really great explanation. I run a landscaping business in San Diego and customers are always asking me about how to enhance their soil, if they should use gypsum, sand, etc. This is a perfect place to send them for the basics of soil. Thanks very much for sharing.
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