Impact of Forest Fertilization on Health of the Hood Canal Watershed Cindy Flint Advisor: Rob Harrison, UW April, 2007 Funded by: • Green Diamond Resource Company • Puget Sound Regional Synthesis Model (PRISM) (with support from the Stand Management Cooperative)
Transcript
Slide 1
Impact of Forest Fertilization on Health of the Hood Canal
Watershed Cindy Flint Advisor: Rob Harrison, UW April, 2007 Funded
by: Green Diamond Resource Company Puget Sound Regional Synthesis
Model (PRISM) (with support from the Stand Management
Cooperative)
Slide 2
Objectives Does forest fertilization with urea result in N
leaching out of rooting zone? Could this negatively impact Hood
Canal.
Slide 3
Background Sill restricts flow in and out of the canal
Historically had periods of low DO Anthropogenic N loading to canal
is worsening this problem
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Eutrophication in Hood Canal Additions of limiting nutrients
Algal blooms Blooms die off Decomposition consumes 0 2 Low DO in
water Fish kills
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Potential Causes of N Loading Erosion? Fertilization? Forests
Agriculture Lawns Septic systems?
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Past Research NO 3 - -N peaks in streams 0.25 mg L -1 to 9.3 mg
L -1 Peaks due to runoff and direct application Steep slopes 15 % N
in streams Buffers 0.45 % N in streams NO 3 - -N additions lasted
longer (up to 1 year) (Meehan et al., 1975; Malueg et al., 1972;
Perrin et al., 1984; Hetherington, 1984; Cline, 1973; Bisson et
al., 1992; McCall, 1970)
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Purpose Does forest fertilization with urea result in N
leaching out of rooting zone?
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Methods 6 Sites Age: 20-40 yrs Site Index: 70-90
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Soil map Shelton Soil series Glacial till
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Site Layout.2 acre Lysimeter nest Control Treatment Fertilized
with 224 kg N ha -1 as urea, March 20th, 2006
Quantified: Overstory N pools (biomass equations and % N)
Understory N pools (calculated biomass and % N) Soil N pools
Methods (cont.)
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Precipitation
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Total N Concentration
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NO 3 -N Concentration
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NH 4 -N Concentration
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DON Concentration
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Leaching
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Total N Leaching
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NO 3 -N Leaching
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NH 4 -N Leaching
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DON Leaching
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Total N Leaching year following fertilization 2 % of applied
N
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Overstory Soil N Pools 26 % of applied N
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Understory Soil N Pools 0 % of applied N
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O Horizon Soil N Pools 27 % of applied N 18 % of applied N
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B Horizon Soil N Pools 0 % of applied N 300 % of applied N
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Implications for Hood Canal 215 ha yr -1 fertilized * 4.2 kg N
ha -1 yr -1 = 903 kg N yr -1 total N load (Green Diamond) Total
surface water TN load (Avg. 05 &06) (Steinberg) = Total
groundwater DIN load (Paulsen, 06) = 536,000 kg yr-1 138,000 kg
yr-1 + 674,000 kg yr -1 Fertilizer leaching = 0.13% total
terrestrial N load to Hood Canal (Leaching)
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Take home message If urea is allowed to infiltrate the soil,
minimal leaching should occur. (in N limited forests) How to
promote infiltration: Buffers!!! (unfertilized, vegetated) No
application on steep slopes No application to streams
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Thank You! Randall Greggs, Green Diamond Resource Company Puget
Sound Regional Synthesis Model (PRISM) Stand Management Cooperative
Rob Harrison, Advisor, College of Forest Resources, UW Brian
Strahm, College of Forest Resources, UW
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Soil pH
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N limitation evidence Overstory % N Soil C/N Ratios