Comparing Growth of Ponderosa Pine in Two Growing Media
Dumroese, R. K. USDA Forest Service, Rocky Mountain Research Station, Proceedings RMRSP-58. p.32-34. National Proceedings: Forest and Conservation Nursery Association - 2008. 2009.
Traditionally, container forest nurseries in the Pacific Northwest grew small conifer seedlings for reforestation in a 1:1 (v:v) Sphagnum peat moss:vermiculite growing medium. Sphagnum peat moss served as the principal water holding matrix while still providing high porosity, and the light-weight vermiculite added water holding capacity as well as high cation exchange capacity (Landis and others 1990). Sawdust is now being offered as replacement for vermiculite, with the standard Sphagnum peat moss:vermiculite mix being modified to a 7:3 (v:v) Sphagnum peat moss:Douglas-fir sawdust mix. Potential advantages of sawdust-amended medium include a more stable supply than vermiculite and reduced costs. Nursery managers in the northern Rocky Mountains were concerned that using a 100% organic medium may result in lower porosity (poorer aeration) that could cause increased root disease expression (Landis and others 1989), particularly of root rot caused by Cylindrocarpon spp. and Phytopthora spp. (Dumroese and James 2005), and that high carbon (C):nitrogen (N) in the non-composted sawdust might lead to nutrient deficiencies and reduced growth (Landis and others 1990).
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Author(s): R. Kasten Dumroese
Publication: National Nursery Proceedings - 2008
Event:
Western Forest and Conservation Nursery Association
2008 - Missoula, Montana
