How Can I Improve My Soils? Nutrient
Deficiencies and Fertilization
Rob Harrison,
PNW Stand Management Cooperative
http://www.forestsoils.org/
Covered today
1) Tree nutrition
2) Nutrient limitiations
3) Risk-rating soils for biomass/nutrient removal
4) Fertilization to maintain/enhance fertility
5) Identifying nutrient deficiency
6) BMP for maintaining or enhancing soil fertility
Table 1 US Timber trends. Data from: Howard, James L. 2003. U.S. timber production, trade, consumption, and price statistics 1965 to 2002. Res. Pap. FPL-RP-615. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 90 p.
Tree Nutrition
Nutrition of DF forests as compared to annual plants
Diagnoses of nutritional needs of DF trees
Sources of nutrients in DF forest ecosystems
Mechanisms by which the nutritional needs of DF trees are met
Nutrient conservation retention processes by forest ecosystems
Advantages of Forests as a
Perennial Plant System• Uptake can take place year around
• Internal translocation of nutrients takes place
• Growth of a tree builds on an existing structure
• Nutrient loss from harvesting is significantly less
Nutrient Content of DF tissue
Tree component Nutrient content (%) N P K Ca Mg
Foliage 1.40 0.21 0.85 0.45 0.11Bark 0.29 0.07 0.31 0.42 0.13Cones 0.65 0.13 1.26 0.06 0.10Branches 0.36 0.07 0.21 0.51 0.05Bole 0.08 0.01 0.05 0.10 0.05
Sources of Nutrients
• Weathering
• Nitrogen fixation
• Atmospheric additions
• Mineralization
• Fertilization
SOILSOILSUPPLYSUPPLY
POTENTIAL USEPOTENTIAL USE
ACTUAL USEACTUAL USE
REMOBILIZEDREMOBILIZED
UPTAKE FROM SOILUPTAKE FROM SOIL
Nutrient Supply and Use
Source: Forest Nutrition Cooperatie
Essential Elements
Slide
foliar nutrient concentration
visual deficiency
hidden hunger
critical point (90% of max)
maximum growth "luxury" consumption
toxicity
deathRobHarrison:growth vs. nutrient conc
Rel
ativ
e gr
owth
Covered today
1) Tree nutrition
2) Nutrient limitiations
3) Risk-rating soils for biomass/nutrient removal
4) Fertilization to maintain/enhance fertility
5) Identifying nutrient deficiency
6) BMP for maintaining or enhancing soil fertility
Regional Long-term Site Productivity StudiesMineral Soil Carbon and Nitrogen to 0.6 m depth:
13
Boistfort Grove
Sustainable Soil Productivity Removals effects on Nitrogen statusPotential Growth Reduction
• Bole-only harvesting removes ~ 5% of N pool
• Total-tree harvesting removes ~ 10% of N pool
(after Johnson et al. 1982)
14
Nitrogen Risk Ratings - Generalized Concept
15
Increasing risk of nitrogen (N) limitations as A / T proportion increases…
A = Aboveground Total N Pool (kg/ha):
forest floor + understory vegetation + standing crop
S = Soil Total N pool (kg/ha) - rooting depth
T = A + S
= T
A =
S =
Evans, J.1999. Sustainability of forest plantations—the evidence. A review of evidence concerning the narrow-sense sustainability of planted forests. Report for the Department for International Development, London, UK. 64 p.
Nitrogen Risk Ratings - Generalized Concept
16
Proportion of site N pool removed:
Increasing risk (after Evans, 1999)
Low Serious Imminent decline
0.1 0.3 0.5
Example 1: Fall River LTSP, Boistfort soil
A / T = 1300 kg N /ha / 14500 kg N/ha = 0.09
= T
A =
S =
Nitrogen Risk Ratings - Generalized Concept
17
Proportion of site N pool removed:
Increasing risk (after Evans, 1999)
Low Serious Imminent decline
0.1 0.3 0.5
Example 1: Fall River LTSP, Boistfort soil
A / T = 1300 kg N /ha / 14500 kg N/ha = 0.09
= T
A =
S =
Nitrogen Risk Ratings - Generalized Concept
18
Proportion of N pool removed:
Increasing risk (after Evans, 1999)
Low Serious Imminent decline
0.1 0.3 0.5
Example 2: Matlock LTSP, Grove series
A / T = 605 kg N /ha / 3705 kg N /ha = 0.16
= T
A =
S =
Nitrogen Risk Ratings - Generalized Concept
19
Proportion of N pool removed:
Increasing risk (after Evans, 1999)
Low Serious Imminent decline
0.1 0.3 0.5
Example 2: Matlock LTSP, Grove series
A / T = 605 kg N /ha / 3705 kg N /ha = 0.16
= T
A =
S =
Covered today
1) Tree nutrition
2) Nutrient limitiations
3) Risk-rating soils for biomass/nutrient removal
4) Fertilization to maintain/enhance fertility
5) Identifying nutrient deficiency
6) BMP for maintaining or enhancing soil fertility
Diagnoses of Nutritional Requirements
Daignostic indicators of deficency symptoms Foliage deficiency symptoms Foliage and soil analysis
Nutrient uptake rates
Covered today
1) Tree nutrition
2) Nutrient limitiations
3) Risk-rating soils for biomass/nutrient removal
4) Fertilization to maintain/enhance fertility
5) Identifying nutrient deficiency
6) BMP for maintaining or enhancing soil fertility
Percent volume response
N rate (lb N/acre)
N200 N300
N200-P88-S154
N200-P88-S168+
N100
N52-P12-K220
Percent volume response
N rate (lb N/acre)
N100
N52-P12-K220
N300N100
N200-P88-S154N200-P88-S168+
N200
N52-P12-K220
N+P
Installations of the PNW Stand Management Cooperative
SILVICULTUREWOOD QUALITY
NUTRITION
MODELING
College of Forest ResourcesUniversity of WashingtonBox 352100Seattle Washington 98195-2100
206-543-5355 phone206-685-3091 fax
RFNRP Installations
RFNRP Installations
Forest floor C/N ratio
Percent Difference in Volume Increment vs Total Nitrogen Fertilizer Applied
0
10
20
30
40
50
60
70
200 400 600 800 1000
Total N Fertilizer Applied (lb/ac)
II
III
IV
V
Site Class:
II : 120-140 ft
III : 100-120 ft
IV: 80-100 ft
V : < 80 ft
Overall results of SMC studies Response vs. N rate. Sidell thesis.
(1)
Results of RFNRP studies
1) N response averaging 20% (unthinned) -30% (thinned) with 400 kg N, highly site dependent.
2) Clearly, both response to N and other nutrients is site controlled. Indicates need for larger scale studies on a wide variety of sites to pin response to site variables.
3) Effects of N fertilization appear to be very long-lived.
Covered today
1) Tree nutrition
2) Nutrient limitiations
3) Risk-rating soils for biomass/nutrient removal
4) Fertilization to maintain/enhance fertility
5) Identifying nutrient deficiency
6) BMP for maintaining or enhancing soil fertility
Nutrient Deficiency Levelssolution cultures (Walker and Gessel 1991)
Element Douglas-fir Hemlock WR Cedar Sitka Spruce Abies
1.8
0.25
1.1
0.18
Nitrogen
Phosphorus
Potassium
Calcium
Magnesium
Sulfur
1.25
0.16
0.6
0.25
0.17
0.35
1.5
0.13
0.6
0.20
0.12
0.4
1.8
0.09
0.4
0.06
0.06
0.15
1.15
0.15
0.50
0.12
0.07
Estimating forest productivity and potential for response to
fertilization: SMC/CIPS paired-tree fertilization project
Hypotheses• Soil and other will predict Douglas-fir
response to N fertilization- Soil bulk density, porosity and texture
- Soil organic matter and nutrient pools
- Climate and soil temperature
- Precipitation and soil moisture
- Site index
- LAI
- Elevation, slope and slope position
- Aspect
- Stand stocking, type and development
Current Paired Tree Trials
• 6 sites installed winter 2007
• 28 sites installed summer 2008
• 2 sites ready spring 2009
• Scouting more to fit into matrix
sedimentary
glacial
igneous
Soil Nitrogen
Covered today
1) Tree nutrition
2) Nutrient limitiations
3) Risk-rating soils for biomass/nutrient removal
4) Fertilization to maintain/enhance fertility
5) Identifying nutrient deficiency
6) BMP for maintaining or enhancing soil fertility
Nitrogen Risk Ratings - Generalized Concept
50
Proportion of site N pool removed:
Increasing risk (after Evans, 1999)
Low Serious Imminent decline
0.1 0.3 0.5
Example 1: Fall River LTSP, Boistfort soil
A / T = 1300 kg N /ha / 14500 kg N/ha = 0.09
= T
A =
S =
Conclusions
- Nitrogen commonly limits forest productivity in PNW
- N-fertilization of forestlands of the Pacific Northwest is an important treatment resulting in higher productivity
- Low sites show the highest % response, high sites the lowest. Higher rates result in higher response.
- Interestingly, N fertilization seems to have long-term effects on new stands, but we have limited data on this.
- Our ability to predict response stand-by-stand is quite limited.