What is heavy or light soil? ASK THE HORT AGENT
Question What is heavy or light soil?
Answer Gardeners and farmers surely know there is a difference from one patch of ground to another. Believe it or not, one cubic foot (ft3) of heavy soil weighs more than the same volume of a light soil. The weight difference is primarily caused by air. Light soils have more air space between the soil particles than heavy soils.
The size of the soil particles is known as the texture. Soil texture is determined by the proportions of clay, silt and sand found in any given sample, and has nothing to do with the amount of organic matter present in the soil. A single grain of sand can be seen with the naked eye; however, a person would have to use a microscope to see a silt particle. An electron microscope would have to be used to see a clay particle. Relatively speaking, the size difference would be like comparing a whiskey barrel (sand), a dinner plate (silt) and a dime (clay).
Soils are basically mixtures of these different particles. Heavy soils contain more clay and light soils contain more sand. The clay particles pack together more tightly and have less air space. Sand particles have the opposite effect.
The perfect gardening soil is called a loamy soil. This type of soil has nearly equal amounts of sand, silt and clay.
Soil texture can have a major impact on many gardening choices. Plant selection, fertilization, irrigation and timing are all affected by soil texture. For example, heavy soils require less water and fertilizer. Light soils hold less water, but may have fewer disease problems and soak up water faster.
Soil texture often makes a difference in sneaky little ways that are never suspected. Issues like winter survivability, germination date (weeds and planted seeds), and even the proper size of your garden tiller are all affected by soil texture. For a farmer, soil texture also determines crop productivity potential, compaction potential and workability.
As opposite as heavy is from light, both ends of the spectrum have one thing in common. Sandy and clay soils can be improved by the generous addition of organic matter such as compost.
If you want more info about soils, then visit this website http://edis.ifas.ufl.edu/SS169
If you do not have internet access, feel free to call me at 910-893-7533, write me at PO Box 1089, Lillington, NC 27546 or email me at gary_pierce@ncsu.edu
There are 12 names of soil textures that cover the combinations of sand, silt and clay. They have names like sandy loam, silty clay, sandy clay, etc… If you want to learn how to classify soil textures, visit this website http://www.ext.colostate.edu/pubs/garden/07723.html Farmers have their own names for these 12 soil textures. These names include heavy, light, kindly light, kindly heavy, good, poor, etc...
Gary L. Pierce
Horticulture Extension Agent
Harnett County | 
