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Media: Rooted in Success
Understanding the general characteristics of growing media, as well as the specific attributes of the media you are using, will enable you to get the most out of your nursery. This set of pages describes the attributes of media and how to manage media for success.
Media is composed of solid, liquid, and gaseous components.
- Solid materials usually constitute 33-50% of the media volume. Spaces, or pores , between the solid particles are filled with air or water. As water moves through container media, it is retained by smaller pores, but drains through larger pores.
- The second fraction of the media, the liquid portion, consists of nutrients, organic materials, dissolved gases, and water.
- The third media phase consists of gaseous materials including oxygen and carbon dioxide. Although media oxygen levels vary from 0-21%, a concentration of at least 12% oxygen is necessary for root initiation to occur. Roots of most plants fail to grow in a media atmosphere containing less than 3% oxygen. The carbon dioxide content of the media may range from 0.03% to 21%; however, very high carbon dioxide contents may be detrimental to plant health (Bilderback, 1982).
Understanding the attributes of each of these media components, as well as the interactions between these components, is essential for the successful operation of a nursery. The following pages describe concepts and provide illustrations of how to effectively manage your media and keep your crops rooted in success.
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