Status of Soil Organic Carbon Stocks in the Small Island Developing States (SIDS).

A Snapshot

Siosiua HalavatauPacific CommunityFiji

A distinct group – 38 UN members, 20 Non-UN members - Pacific, Caribbean, and AIMS

High Vulnerability• CC & sea level rise• Biodiversity• Natural disasters• Dependent on fossil

fuel• Isolation• Smallness• Waste disposal• Poor quality H20• Competition between

land use options

Low Adaptive Capacity

• Weak Technical• Limited Financial• Limited

Institutional capacity

• Data issue

Meeting Commitments• Implementing the SAMOA

Pathway • Milan declaration• Implementation of the

Barbados Programme of Action and the Mauritius Strategy of Implementation

Agriculture and soils rarely mentioned

What are SIDS?

COP 21 and 22• Although agriculture is not explicitly mentioned in the original text of the Paris

Agreement, agriculture, forestry and land use changes are collectively responsible for one-fifth of all global greenhouse gas emissions.

• Food and agricultural “policy frameworks need to be drastically modified” to address climate change and food security at the same time (FAO).

• Voluntary soil initiative 4 per 1000 – Intended Nationally Determined Contribution (INDC)

• One aspect of climate change receiving major attention at COP 22 meeting for the first time was its effects on agriculture

• The key question is- how can we keep producing food and yet maintain Soil Organic Carbon??

- will it alleviate some of the secondary cascade of problems associated with decreasing organic carbon?

Atoll – natively poor

Biodiversity

Use of plant residues Mechanization

Cultivation Soil erosionOver-stock

Soil Organic C Status - Pacific

1. Total and labile C decline with changes in vegetation and intensity of mechanical tillage.2. Contribution of C4 plants to soil C increases with mechanical tillage3. MWD decreased significantly with increased intensity of tillage and a lesser extent with intensity and

length of cropping

Tc (ton/ha) Lc(ton/ha) %SC /C4 MWD(mm)0

10

20

30

40

50

60

70

Tc, Lc, %SC from C$ plants and MDM under different land use systems

Primary forest Permanent cropGuinea grass fallow Mechanically cropped and grass fallowRepeatedly mechanically cropped

Tc, Lc, SC from C4 plants and MDW

Tc (t

/ha)

, Lc

(t/h

a) %

Sc,

and

MD

M (m

m)

Manu et al, 2014

Tc (ton/ha) Lc (ton/ha) %SC /C4 MWD(mm)0

10

20

30

40

50

60

70

80

9080

16

72.65

47

8

55

2.48

41

7

38

2.65

34

6

64

1.77

28

5

73

0.77

Tc, Lc, %SC from C4 plants and MWD under different land use systems

Primary forest Permanent cropGuinea grass fallow Mechanically cropped and grass fallowRepeatedly mechanically cropped

Tc, Lc, SC from C4 plants and MWD

Tc (

%),

LC (t

/ha)

% C

4 pl

ant,

an

d M

DW

(mm

)

Soil Organic C Status – Sugarcane Systems - MauritiusSimilar results were seen in Fiji (Morrison and Gawander, 2016), and Caribbean for sugarcane (Sierra et al, 2015)

• Soil C reduced in the top 15cm cf to NV• Increased subsoil C indicating redistribution to deep

horizon.• Native C decreased significantly and compensated by

C inputs from sugarcane residues

Umrit et al, 2014

Soil Organic C Status – Atolls

Deenik and Yost 2006

Donato et al, 2012

Sites pHUnits

ECµSiemen

Nutrients (mg/l)N P K Fe Cu Mn

KiribatiTanaea (tomato)

7.8 870 54 60 150 1.4 1.0 0.2

Takaman 7.9 676 54 40 55 0.2 1.0 0.2RMILaura Station 8.0 176 26.4 38 35 2.2 1.6 0.2Wacner’s farm 8.1 162 22.8 21 40 1.0 2.1 0.3

Soil Analyses of some atoll soils (Current work)

Multiple Nutrient Deficiencies on Atolls

Soil Organic C Status – Atolls

Results reinforce need to improve limiting nutrients in compost

Deenik and Yost 2006

Can we improve SOC Stock?

Land Use Total C (t C/ha) 0.4% requirement (ton C/ha)

Primary Forest 80 0.32Guinea grass fallow 41 0.16Repeatedly mechanically cropped

28 0.11

Sugarcane monocrop 104 0.42Atoll 26 0.10

Join 4 per 1000

Farm smart to increase SOCBabai pit in Kiribati

Organic Agr in Maldives Alley Cropping in Caribbean

Traditional Bush Fallow in Tonga

Mucuna Cover Crop widely used in the Pacific

Soil Health

Results

a b c d0

5

10

15

20

25

30

35

Yield of taro as affected by treatment treatments in Mua Village

Treatment

Taro

Yie

ld (k

g/pl

ot)

Kavatotoe Lofeagai0

200

400

600

800

1000

1200

1400

1600

Effect of compost on yields of sweet potato at 2 sites in Funafuti, Tuvalu

No Compost Compost

Experimental Sites

Yiel

d (g

/pla

nt)

a- Lime + Mucuna + Fertilizer (soil test) + Lime (soil test)b- Lime + Mucuna + Fish manure + Rock Pc- Mucuna + NPK 13:13:21 + Urea (Conventional)d- Mucuna + (Farmer’s Choice)

Showing improving soil C can increase food production as well improve soil properties and resilience

TN(%) Tc (%) Lc (mg/g)0123456789

10

Effects of different mulches on TN, Tc, and Lc

Control Plastic Coconut frondsCoconut sawdust Guinea grass

Total N, Total C and Labile C

TN a

nd T

c (%

) and

Lc

(mg/

g)

Wuddivira & Stone, 2006

Conclusion • Though SIDS may be vulnerable but the future looks bright• Maintenance of adequate levels of SOC is crucial for biological,

chemical, and physical functioning of soils• Long term data show that we have done well in agriculture and

managing SOC!!! • But easier for clay soils than sandy soils (atolls)• We need to engage in the 4 per 1000 initiative• We need policy support – regional and national• We need to generate scientific evidences for the policy

development

Acknowledge the followings with their works in SIDS

PacificJohn Morrison – University of New England Viliami Manu – CEO MAFF TongaACIAR Soil Health projects in the Pacific Islands

MaldivesMr. Mark Garret - Permaculturist

MauritiusGunshiam Umrit and team – Mauritius Sugarcane Research

CaribbeanKaren Montiel - Inter-American Institute for Cooperation on AgricultureAinsworth Riley - Inter-American Institute for Cooperation on Agriculture Adrien Spence – University of West Indies