guideline for soil sampling and processing
TRANSCRIPT
Guideline for soil sampling &Processing
Ermias Betemariam ([email protected]) Keith Shepherd
13 April 2015Kampala
ContextOutline
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• Context
• Sampling
• Field work
• Lab work
Context• 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)
• Increasing demand for soil data at fine spatial resolution
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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)
• Land productivity is key to feed the world• Land degradation remains a global challenge and reducing/reversing land
degradation is a development/research priority• Soil comes to the global agenda: sustainable intensification • Global Environmental Benefits - land degradation and soils are among the priority
global benefits (GEF/UNCCD)
Context
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Soil nutrient balance• Inputs
– Litter, roots, branches
• Outputs
• Autotrophic respiration: roots
• Heterotrophic respiration: CO2
respiration of soil organisms that use dead plant matter as a food source
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Guidelines
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Remote sensing for carbon monitoring
Consistent field protocol
Soil spectroscopyCoupling with remote sensingPrevalence, Risk factors, Digital
mapping
Sentinel sites Randomized sampling schemes
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No. District No of EAs No. of Farms No of soil samples
1 Serere 15 180 360
2 Sironko 15 180 360
3Iganga and Mayuge 45 540 1080
Total 75 900 1800
How many samples
Field navigation
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Plot layout
Plots are laid out with four subplots (Y- frame)
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Field workPreparation for field work• Proper preparation before going to the field • Collate existing information (e.g. soil map)• Train staff and pilot all procedures• Prepare logistics in terms of transport, etc.
Collecting field samples• Locate the predetermined sample location• Take composite soil samples from 4 points using
auger• Collect any associated data required (e.g. land
management)
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Field work- composite samples
Field work- Texture analysis
Soil sampling
Field soil data collection Soil sample to be send to the lab for processing
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Sample processing
• Drying• Crashing• Sieving
– 50 gm for spectral analysis= all samples– 750 gm soil for reference analysis = 10% of of the total samples
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Soil Infrared Spectroscopy
Rapid Low cost Reproducible Predicts many soil functional properties
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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
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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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Things to be careful [2]
Proper labeling
Avoid contamination
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Properly locate your plots/sites
Ermias Betemariam | Hands-on soil infrared spectroscopy training course | Nairobi | Nov. 12, 2013 | 19
Preliminary results from Ethiopia
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Preliminary results from Ethiopia
• More research on cost-effective measurement tools• Reduce uncertainties in measurements- error propagates• Develop national capacities, networking and partnership • Enable decision makers have clear understanding of soil status and trends
Finally…
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