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Hands-on Soil Infrared Spectroscopy Training Course
Getting the best out of light11 – 14 November 2013
Applications of soil spectroscopy on Land Health Surveillance
Ermias BetemariamErick Towett
Context (i)• Soil comes to the global agenda:
– Sustainable intensification took soil as a x-cutting
– Global Environmental Benefits - land degradation and soils are among the priority global benefits (GEF/UNCCD)
• SOC as useful indicator of soil health
• Importance of soil carbon in global carbon cycle and climate mitigation
• carbon trading purposes requires high levels of measurement precision
• Increasing demand for soil data at fine spatial resolution
2Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
Context There is a lack of coherent and rigorous sampling and assessment
frameworks that enable comparison of data (i.e. meta-studies) across a wide range of environmental conditions and scales
Soil monitoring is expensive to maintain Soil degradation and loss is a challenge High spatial variability in soil properties- large data sets reduce uncertainty
Context (iI)
High spatial variability of SOC can rise sevenfold when scaling up from point sample to landscape scales, resulting in high uncertainties in calculations of SOC stocks. This hinders the ability to accurately measure changes in stocks at scales relevant to emissions trading schemes (Hobley and Willgoose, 2010)
Soil spectroscopy key for Land Health Surveillance
Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 | 3
Land Health (SD4)Land Health - the capacity of land to sustain delivery of essential ecosystem services
Land health surveillance aims to provide statisticallyvalid estimates of land health problems, quantify keyrisk factors associated with land degradation, andtarget cost-effective interventions to reduce or reversethese risks.
4Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
Land Health Projects
No. Name of project
1Africa Soil Information Service (AfSIS)/Africa Soils (SSA)
2Strengthening capacity for diagnosis and management of soil micronutrient deficiencies (SSA)
3Soil monitoring protocol for the World Bank Living Standards Measurement Study (Ethiopia & ..)
4Carbon sequestration options in pastoral & agro-pastoral systems in Africa (Burkina Faso & Ethiopia)5Land health surveillance for high value biocarbon development (Kenya, Burkina Faso & Sierra
Leone)6Land health surveillance system for smallholder cocoa in Ivory Coast
7Trees for food security in Eastern Africa (Rwanda, Ethiopia, Burundi & Uganda)
8Land health surveillance for mitigation of climate change in agriculture (Kenya & Tanzania)
9Land health surveillance system in support of Malawi food security project (Malawi)
10Land health surveillance system for targeting agroforestry based interventions for sustainable land productivity in the western highlands of Cameroon
11A Protocol for Measurement and Monitoring Soil Carbon Stocks in Agricultural Landscapes
Land Health Projects (i)
5Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
6
Land Health Projects (ii)
Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
Land Health out-scaling projects (iii)
Tibetan Plateau/ Mekong
Parklands Malawi
National surveillance systemsRegional Information Systems
Project baselines
Rangelands E/W AfricaSLM Cameroon MICCA E. Africa
Global-Continental Monitoring Systems
Evergreen Ag / Horn of Africa
CRP5 pan-tropical basins AfSIS
EthioSIS- Ethiopia
7
Cocoa - CDI
Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
AfSIS ✓60 primary sentinel sites
➡ 9,600 sampling plots➡ 19,200 “standard” soil samples➡ ~ 38,000 soil spectra
AfSIS: Soil functional properties (1)
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EthioSIS 97 Sentinel sites
Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
AfSIS: Soil functional propertiesSpectral diagnostics tools can be used to produce soil maps
Prediction map for soil organic carbon for sub-Saharan Africa. (Source: Africa Soil Information Service)
9Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
AfSIS: Soil functional propertiesFrom polygon-based to probabilistic mapping
+
Probability of observingcultivation
Current lime requirement ? ~ min [prob(pH < 5.5), prob(cult)]
Probability topsoil pH < 5.5 ... very acid soils
Grid-based probabilistic maps increases the reliability of the map and its power to be combined with other data sources (remote sensing & terrain data)
(Walsh, 2013)
=
Taxonomic soil classification systems provide little information on soil functionality in particular the productivity function (Mueller et al 2010)
10
Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
Living Standards Measurement Study-LSMS-IMS (3)Improve measurements of agricultural productivity through methodological validation and research
Mobile phones for quick soil screening- being tested
11
Low cost MIR soil testing for smallholder farmers
Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
Carbon sequestration in pastoral & agro-pastoral systems (4)
Effects of range management on soil organic carbon stocks in savanna ecosystems of Burkina Faso & Ethiopia
Fire (controlled burning -19 years) – Burkina Faso
Grazing (Exclosures 12- 36 years) – Ethiopia
Fire influence:• Carbon allocation - SOC gain• Decrease input - SOC loss
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Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
ResultsNo Sig difference in SOC between burned and unburned plots
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Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
ResultsNo Sig difference in SOC between burned and unburned plots
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Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
ResultsNo sig. difference in SOC between closed and open plots for all age categories
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Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
Challenges in cocoa productionBiocarbon development in East and West Africa (5)• Develop effective and cost efficient carbon monitoring, reporting and
verification systems that can enable smallholders to access carbon markets• Soil spectroscopy will be key component
Estimating biocarbon using LiDAR data- Taita, Kenya(a) indigenous forest, (b) mixed stand of local and exotic species (Eucalyptus sp.) and (c) cropland with scattered trees
Janne et al., 2013
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Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
Smallholder cocoa in Ivory Coast-V4C (6)
Disease + pest?
Soil fertility?
Major challenges
LDSF and soil spectroscopy to identify constraints & target interventions in cocoa production
17
Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
Trees for food security –ACIAR
Rwanda
Ethiopia
Characterize land health constraints and assessing Agroforestry intervention outcomes
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Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
Mitigating Climate Change in Agriculture-MICCA (8)
East African Dairy Development (EADD- Kenya)
Conservation agriculture (CARE- Tanzania)
Characterize (baseline) and assess impacts of climate smart agriculture practices
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Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
Measurement and Monitoring Soil Carbon Stock (11)Can we measure soil carbon cost effectively?
20
Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
Land Health Surveillance
Consistent field protocol
Soil spectroscopyCoupling with remote sensingPrevalence, Risk factors, Digital
mapping
Sentinel sites Randomized sampling schemes
21
Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
Measurement and Monitoring Soil Carbon Stock (11)
Why measure carbon?
1
What will the protocol deliver?
2
3How much will it
cost?
4 Sampling
5 Field work
6 Lab work
7 Data analysis
8 Presenting results
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Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
Sample size determination
Sample allocation Moisture content
Soil Carbon stock Error
Measurement and Monitoring Soil Carbon Stock (11)
Web and excel based tool
…. and reporting
DATA INFORMATION KNOWLEDGE WISDOM
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Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
A management that leads to a DECREASE in bulk density will UNDER ESTIMATES SOC stocks & vice versa
C conc.(%) Depth(cm)Bulk density (g/cm) SOC stock (Mg/ha) Error
1.5 150 1.2 270 1.5 150 1 225 -16.67%
Monitoring SOC stocks
(Ellert and Bettany, 1995)
Bulk density as confounding variable in comparing SOC stocks
Think mass not depth
Why cumulative soil mass?
24
Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
10 50 100 150 200 2500
2000
4000
6000 NIR spectroscopyThermal oxidationSample preparationSoil sampling
Number of samples
Co
st (
US
D)
Personnel Others0
3
6
9
12
15NIR spectroscopy Thermal oxidationSample preparation Soil sampling
Co
st p
er
sam
ple
(U
SD
)
Cost –error analysis
0 500 1000 15000
2000
4000
6000
8000 Thermal oxidationNIR spectroscopy
Number of samples
Cost
(USD
)
Comparisons of costs of measuring SOC using a commercial lab and NIR
CostIR is cheaper (~ 56%) than dry combustion method for large number of samples
ThroughputCombustion ~ 30-60 samples/dayNIR ~ 350 samples/dayMIR ~ 1000/day
Cost –error analysis
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Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
Cost –error analysis
0 200 400 600 800 10000.00
2.00
4.00
6.00
8.00
10.00
Number of samples
Hal
f 95%
con
fiden
ce in
terv
al (t
C h
a-1)
0 5000 10000 15000 200000.00
2.00
4.00
6.00
8.00
10.00
Cost of carbon measurement (USD)
Hal
f 95%
con
fiden
ce in
terv
al (t
C h
a-1)
Cost –error analysisCosts of measurement often exceed the benefits – soil spectroscopy address this challenge
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Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
Activity Sources of uncertainty
Sampling Sampling design (random, stratified random)
Sample size
SOC measurement
Natural variability (spatial)
Sample preparation (e.g. contamination, subsampling)
Lab method used (instrument resolution)
Human error
Field data collection (e.g. soil mass, volume)
SOC prediction using IR
Imported uncertainties (from reference data)
Model (assumption) Instrument and human errors
Mapping SOC
Covariates used
Image pre -processing (geometric and radiometric corrections)
Scale/resolution (e.g. farm vs landscape)
Model (assumption, strength)
Sources of uncertainty
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Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
Common causes of measurement uncertainty• the instruments used, • the item being measured,• the environment, • the operator, • other sources
28
CASE 1 High precision (repeatable) High accuracy Random error (less biased)
CASE 2 High precision (repeatable) Low accuracy Systematic error (biased)
CASE 3 Low precision (not repeatable) High accuracy Random error (less biased)
CASE 4 Low precision (not repeatable) Low accuracy Systematic error (biased)
Accuracy versus precision
Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
Things to be careful!
Proper labelingAvoid contamination
Lets do it right
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Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
Data archiving/publishingDatasaving – dataverse: http://thedata.harvard.edu/dvn/
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Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
• More research on cost-effective measurement tools• Web services are needed that allow optimised soil information to be
automatically exchanged via the internet• Proximal soil sensing
• Reduce uncertainties in measurements- error propagates• Develop national capacities, networking and partnership • Baselines are established for important soil properties across Africa• Soil spectroscopy filling the data gaps- at National, Regional & Global
levels• Enable decision makers have clear understanding of soil status and trends• Spectroscopy is proved good- adoption and application
• Cross sentinel/regional sites analysis
Finally…
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Ermias Betemariam, Erick Towett | Hands-on soil infrared spectroscopy training course | Nairobi | May 2014 |
Thank you