Sulfur Requirements of Nitrogen Fertilized Douglas-fir

Authors: Turner, John; Lambert, Marcia J.; Gessel, Stanley P.

Source: Forest Science, Volume 25, Number 3, 1 September 1979 , pp. 461-467(7)

Publisher: Society of American Foresters

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Abstract:

In a series of Pacific Northwest Douglas-fir nitrogen fertilizer trials, foliage SO₄-S was found to be a correct predictive index of response in 17 of the 19 stands studied, whereas using foliage nitrogen concentrations the correct prediction was obtained in only 12 stands. To obtain a tree growth response to an application of 220 kg/ha N, resulting in an increase of 0.4 percent foliage N, approximately 0.04 percent foliage SO₄-S is required. As SO₄-S concentrations are not routinely determined in the fertilizer project laboratories, other parameters providing potential indirect estimates of SO₄-S status have been assessed. Using a combination of soil parent material and the separately measured soil nitrogen content (kg/ha), predictions of fertilizer response comparable to those using foliage SO₄-S concentrations have been obtained. Trees located on soils derived from sedimentary and glacial parent materials responded to N fertilization when the soils contained less than 8,000 kg/ha N in the rooting zone whereas no trees were found to respond on soils derived from pumice (less than 2,400 kg/ha N) and basalt parent materials. In these latter cases foliar SO₄-S levels were less than 0.005 percent. Forest Sci. 25:461-467.

Keywords: Pseudotsuga menziesii; fertilizer application

Document Type: Journal article

Affiliations: 1: College of Forest Resources, University of Washington, Seattle 98195 U.S.A.

Publication date: 1979-09-01

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