fertilization of tree plantations
TRANSCRIPT
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Optimum Fertilization forTree Plantations
Dr. Randy S. Senock
Assistant Professor of Tropical Forestry
University of Hawaii at Hilo
College of Agriculture, Forestry and
Natural Resource Management
Dr. J. B. FridayExtension Forester
UH CTAHR Cooperative Extension Service
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Optimum Fertilization
Biological
Economical
Environmental
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Basic Tree Crop Nutrition
Rapid Growth =High Demand
Nutrient Depletion =
Low Yields
Depends on
Stage of Stand
Development
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Three General Nutritional Stages
Establishment Rapid Growth Maintenance
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Two Growth Phases
Before Canopy Closure After Canopy Closure
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General Pattern of Tree
Growth
0
1
2
3
4
5
6
7
Ste
mm
ass(kgCm-2
)
0 2 4 6 8 10Plantation age (years)
0
0.2
0.4
0.6
0.8
1.0
1.2St
emincre
ment(gCm-2
yr-2
)
Increment
Stem mass
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Key is Canopy Closure
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Before Canopy Closure
Establishment Stage
little nutrient
accumulation
split applications
N,P,K 4 oz or
100g\tree planting
repeat w/in 6
months
Little effect on long term fertility
Good root zone development
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Before Canopy Closure
Eucalyptus N demand during
Rapid Growth Stage in Hawaii
0.60%
570 kg\ha 350 kg\ha 260kg\ha
Soil Nitrogen Content
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High Nitrogen = High
Photosynthesis
P
hotosyntheticCapacity
F
oliageN(mmolm-2)
0
40
80
120
Control Fertilized
P
hotosyntheticCapacity
F
oliageN(mmolm-2)
P
hotosyntheticCapacity
F
oliageN(mmolm-2)
0
40
80
120
Control Fertilized
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High Photosynthesis = High
Production
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Control Fertilized
High Leaf Area = High Production
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Poor nutrition =Low leaf area
= low production
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After Canopy Closure Nutrient
accumulation
greatest in stem
Leaf biomassreaches equilibrium
Large proportion of
nutrient requirementmet by recycling
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Nutrients in a Eucalyptus saligna Plantation
% of Total
N P K Ca MgTrunk
Bark
Branches
Leaves
Total
12
08
17
63
100
49
09
14
28
100
24
15
26
35
100
08
27
34
31
100
14
30
17
39
100
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Choice of Fertilization
Mineral Applications
correction of
known deficiencies
establishment onpoor soil
conditions
stimulating growth timing
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Choice of Fertilization
Intercropping with
Nitrogen Fixing
Trees
N availability limitsgrowth
N fixation rates
substantial little competition to
crop tree
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Crop Tree Height EffectsPure stands Mixed stands
0
5
10
15
20
25
30
Treeheight(m
)
0 2 4 6 8 10
Age (yr)
Albizia
Eucalyptus
0
5
10
15
20
25
30
Treeheight(m
)
0 2 4 6 8 10
Age (yr)
Albizia
Eucalyptus
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0
50
100
150
200
250
300
350
400
Treebioma
ss(Mg/ha
)
0 25 34 50 66 100
%Albizia in stand
Eucalyptus Albizia
Crop Tree Biomass Effects
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GreenhouseSoil Bioassay
Trails
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Biological Nitrogen Fixation
Atmospheric Nitrogen N2
toAmmonia NH3
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N Fixation vs Mineral N Continuous
moderation Organic
Long term effects
Single large pulse
Inorganic
Short term effects
Problem: Trees that fix N(for example Acacia, Albizia, or Casuarina)
are very often invasive weeds
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Take home lessons Fast-growing trees demand nutrients.
There are stages in a trees growth, and fertilizingwhile the canopy develops is critical.
Leaves demand more nutrients to develop than wood
does. Low fertility can lead to sparse crowns and lowproduction.
Look into organic sources that may be available.
Integrating N-fixers into the system can have long-term benefits.
Reference: Optimum fertilization for tree plantations in
Hawaii. Randy Senock. In: Growing Working Forest forHawaiis Future.