Horticultural Growing Mediums and Soil Amendments

 

Soil: A mixture of inorganic and organic materials that are in solid, gaseous and aqueous states. It not only provides water and nutrients, but provides a base for plant anchorage.

Characteristics:

Inorganic Components:

Sand: Is heavy, has low water-holding capacity so is good for drainage, and has low cation exchange capacity.
Perlite: Non- buffering or nutrient holding medium. It is a light popped volcanic rock with no cation exchange capacity. Good for aeration and drainage. It is the Styrofoam type substance found in most potting soils.
Vermiculite: An expanded mica mineral. A high buffering aggregate with high water-holding and cation exchange capacity.
Pumice: Crushed volcanic rock with low cation exchange and water-holding capacity; good for drainage.

 

Organic Components:

 

 

Peatmoss: Many different kinds but most common and best to use is sphagnum. It is decomposed organic matter that has a low pH and has high water-holding and cation exchange capacity.

Coconut Coir: Shredded coconut fibers. Has high water-holding capacity, some cation exchange capacity, and is often used in hydroponics.
Cottonseed Meal: good organic source of the three major macro-nutrients (Nitrogen, Phosphorous, and Potassium). Is slow release and lowers the pH of the soil.
Mulch: often composed of chopped/shredded trees or crop residue such as rice hull or dry foliage. Has high Carbon content and is great for prevention of water loss and weed growth.

 

 

*Soil in every region varies greatly and will need different amending and possible fertilization. The commercial fertilizers offered by most nurseries contain the most necessary of macro-nutrients; Nitrogen, Phosphorous (as numerous phosphate compounds), and Potassium (as Potash). If your soil type and quality is unknown you should, at the very least, get an at home test for pH and macro-nutrient levels. For troublesome soils and a more comprehensive test; send a soil sample into your local soil testing lab.
*It is important to not overuse fertilizer, especially when it contains Phosphorous. Large amounts are damaging to the environment and unless it is needed you should get a phosphate free fertilizer. When possible ALWAYS use organic fertilizers.

For more information on fertilizers click here: http://www.tfi.org/

*Note: Many different companies offer soilless growing mediums for horticultural and greenhouse use. This is a list of the major soil media and not completely comprehensive. For more information on other soil amendments and possible growing media click here: http://www.americansoil.org/index.html

This webpage was designed by Alex Hill, for Dr. Chiwon Lee, PLSC 211.

References:

http://www.ext.colostate.edu/Pubs/Garden/07235.html
http://www.botanicaldomain.com/images/produits/perlite.jpg
http://www.rosewoodpackaging.co.uk/images/uploads/vermiculite(1).jpg
http://www.dermaxime.com/images/pumice.jpg
http://www.ndsu.nodak.edu/instruct/chlee/plsc210/
http://4.bp.blogspot.com/_9QOR3_5fwIs/Sd_HvxVL_GI/AAAAAAAAAm8/A-xV7vIDP88/s400/peat_moss.jpg
http://www.brew-dudes.com/wordpress/wp-content/uploads/2009/06/rice-hulls.gif
http://imgs.tootoo.com/44/61/4461ccb0feb05f32e385b9c58b93cf71.jpg
http://www.planetnatural.com/site/cottonseed-meal.html
http://sllawnservice.com/yahoo_site_admin/assets/images/CypressMulchhttp:.//www.dullmensclub.com
http://www.americansoil.org/----link
http://www.tfi.org/