What's in your Douglas-fir bark?

Abstract

Douglas-fir bark is a common waste product of forest industry, and has potential use as a substrate in container nurseries. Douglas-fir bark (DFB) is strongly acidic and contains amounts of phosphorus, potassium, iron, copper and manganese within or above the levels recommended for growing container crops. As the pH of DFB decreases, electrical conductivity and amounts of extractable phosphorus, calcium, magnesium, boron, and iron increase. Although liming unfertilized DFB with calcium carbonate up to 3 kg/m3 (5 lb/yd3) is effective at raising pH, the resulting pH is higher than desired for container plants after 6 incubation weeks. Native phosphorus in aged DFB leaches quickly under typical nursery conditions, but it may still be a reliable phosphorus source for plant growth for at least a month, providing pH is kept low.Bark screen size seems to have a stronger effect on the uniformity of DFB chemical properties throughout the year than does bark age. Non-amended fresh and aged DFB provided sufficient micronutrients for the growth of annual vinca for up to 2 months when pH was kept low (< 5.7).

Parent Publication

• National Proceedings: Forest and Conservation Nursery Associations-2007

Citation

Buamscha, M. Gabriela; Altland, James E. 2008. What''s in your Douglas-fir bark?. In: Dumroese, R. K.; Riley, L. E., tech. coords. National Proceedings: Forest and Conservation Nursery Associations-2007. Proc. RMRS-P-57. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. p. 89-103