Fertilization of Tree Plantations

8/13/2019 Fertilization of Tree Plantations

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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


F

oliageN(mmolm-2)

P


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.

Fertilization of Tree Plantations

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