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Urea fertilizer increases growth of 20-year-old, thinned Douglas-fir on poor quality siteAuthor(s): Richard E. Miller; Donald L. Reukema
Source: Res. Note PNW-RN-291. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station. 8 p
Publication Series: Research Note (RN)
Station: Pacific Northwest Research Station
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DescriptionIn 20-year-old, site V Douglas-fir in southwest Washington, fertilizing with nitrogen increased average 5-year diameter and height growth of concurrently released dominant trees by about 85 percent. There was no additional response when phosphorus, potassium, and sulfur were added with the nitrogen fertilizer. Thinning with no other treatment in this moderately stocked plantation did not increase 5-year diameter growth, and it reduced height growth by about 25 percent. Although this reduced height growth will probably be offset by increased growth in the future, managers of nitrogen deficient sites should consider fertilizing shortly before or after thinning to accelerate response to release.
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CitationMiller, Richard E.; Reukema, Donald L. 1977. Urea fertilizer increases growth of 20-year-old, thinned Douglas-fir on poor quality site. Res. Note PNW-RN-291. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station. 8 p.
KeywordsFertilizer response, height, diameter, nitrogen fertilizer response, urea, site class, thinning
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