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Keywords: fertilization
soil properties
111
Abstract: Soil concn of C, N, P, Ca, Mg, K, pH, and CEC were compared at two forest
sites of contrasting mineralogy and management in Washington, U.S.A., after the application of
municipal biosolids. The soil on the Pack forest site was an extremely coarse-textured outwash
soil whilst that of the Mt. Pilchuck Tree Farm was a sandy outwash soil. The Pack forest was
characterized by 80-yr-old second growth Douglas fir (Pseudotsuga menziesii) with an understory
of salal (Gaultheria shallon). The Mt. Pilchuck Tree Farm site was characterized by 60-yr-old
second growth Douglas fir with an understory of salal. Both sites were harvested and cleared
prior to the initiation of the studies. The forest floors were different in the biosolids-amended
soils compared with the unamended soils, with more highly humified material and fewer fine
roots. Large increases in C, N, and P concn in the amended plots were restricted to the top 27 cm
of soil. Ca and Mg increases were observed at the Pack Forest amended site but not at the Mt.
Pilchuck Tree Farm site. At both sites the pH was lower in the amended plots. The differences
between the sites are discussed with reference to soil type and management practices.
Implications for long-term nutrient retention are considered.
249. Harrison, R.B., C.L. Henry and D.S. Xue. 1994b. Magnesium deficiency in Douglas-fir and grand
fir growing on a sandy outwash soil amended with sewage sludge. Water,-Air,-and-Soil-Pollution
75(1/2): 37-50.
Keywords: fertilization
tree/stand health
tree physiology
soil properties
Abstract: Soil and plant samples were collected from chlorotic plantations of grand fir
(Abies grandis) and Douglas fir (Pseudotsuga menziesii) near Seattle, Washington state, USA, in
winter 1989. The soils had been amended in 1981 with an average of 300 dry t/ha of municipal
sewage sludge. The sludge amendment resulted in an N application rate of approximately 8000
kg/ha. Foliage analysis indicated that a severe Mg deficiency (0.25 g/kg in sludge-treated vs. 0.93
g/kg in untreated areas) might be the cause of chlorosis. No other nutrient showed concentrations
in the deficient or toxic ranges. Trace metal levels in foliage were increased significantly for Ni,
Cd and Cr at sludge-treated sites, but were not at toxic levels. Soil samples taken to a depth of 1.4
m indicated the potential for soil acidification (up to 0.9 pH unit) in soil surface horizons. In
addition, exchangeable Ca, Mg and K may have been depleted in surface horizons. Exchangeable
Al and Fe were greater in the surface of sludge-treated sites. These observations, and the loss of
much of the nitrogen added during the sludge amendment, indicated that nitrification and cation
leaching were the most likely mechanism for acidification and depletion of exchangeable cations.
Fertilizing the plantation with MgSO4 or dolomitic limestone was carried out in spring 1990.
New foliage collected in June 1990 was non-chlorotic and significantly higher in Mg
concentration than unfertilized foliage (1.1. vs. 0.7 g/kg, respectively). The results of this study
indicate that it is important to assess the potential for initiating a nutrient deficiency due to
secondary effects of sludge application in forest systems.
250. Harrison, R.B., E.C. Turnblom, C.L. Henry, P. Leonard, R. King and R. Gonyea. 2002. Response
of three young Douglas-fir plantations to forest with low rates of municipal biosolids. Journal-of-
Sustainable-Forestry 14(2/3): 21-30.
Keywords: fertilization