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ARS Home » Research » Publications at this Location » Publication #180154
Title: HEALTHY SUBSTRATES NEED PHYSICALS TOO!

Author
item BILDERBACK, TED - NCSU
item WARREN, STUART - NCSU
item OWEN, JAMES - NCSU
item Albano, Joseph

Submitted to: HortTechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2005
Publication Date: 10/1/2005
Citation: Bilderback, T.E., Warren, S.L., Owen, J.S., Albano, J.P. 2005. Healthy substrates need physicals too!. 2005. HortTechnology. v.15:747-751.

Interpretive Summary: Growing media used in nursery container production is typically a blend of organic and inorganic constiuents. The organic components in such growing media are vulnerable to decomposition, and as this occurs, changes in the media's air porosity and water retention takes place. In the commercial nursery industry, crops frequently remain in containers for longer periods than one growing season (18 to 24 months) therfore such changes in growing media overtime due to the decomposition of organic components is a concern. Decomposition of organic components can create an overabundance of small particles that hold excessive amounts of water, thus creating limited air porosity. Mineral aggregates such as perlite, pumice, coarse sand, and calcined clays do not decompose, or breakdown slowly, when used in potting substrates. Blending aggregates with organic components can decrease changes in physical properties over time by dilution of organic components and preserving large pore spaces, thus helping to maintain structural integrity of the growing media.

Technical Abstract: Many research studies have evaluated potential organic and mineral container substrate components for use in commercial potting substrates. Most studies report results of plant growth over a single production season and only a few include physical properties of the substrates tested. Furthermore, substrates containing predominantly organic components decompose during crop production cycles producing changes in air and water ratios. In the commercial nursery industry, crops frequently remain in containers for longer periods than one growing season (18 to 24 months). Changes in air and water retention characteristics over extended periods can have significant effect on the health and vigor of crops held in containers for a year or more. Decomposition of organic components can create an overabundance of small particles that hold excessive amounts of water, thus creating limited air porosity. Mineral aggregates such as perlite, pumice, coarse sand, and calcined clays do not decompose, or breakdown slowly, when used in potting substrates. Blending aggregates with organic components can decrease changes in physical properties over time by dilution of organic components and preserving large pore spaces, thus helping to maintain structural integrity. Research is needed to evaluate changes in container substrates from initial physical properties to changes in air and water characteristics after a production cycle.