Presentation by Klaus Butterbach-Bahl, Björn Ole Sander, David Pelster, and Eugenio Díaz-Pinés. Presentation of the key elements of the the Quantifying Greenhouse Gas Emissions from Managed and Natural Soils chapter in the recently published book Methods for Measuring Greenhouse Gas Balances and Evaluating Mitigation Options in Smallholder Agriculture

1. INSTITUTE OF METEOROLOGY AND CLIMATE RESEARCH, ATMOSPHERIC ENVIRONMENTAL RESEARCH, IMK-IFU
DIVISION/Working Group… (change in master view)
Quantifying Greenhouse Gas Emissions
from Managed and Natural Soils
Klaus Butterbach-Bahl1,2, Björn Ole Sander3, David Pelster2, Eugenio Díaz-Pinés1
1: Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU)
2: International Livestock Research Institute (ILRI) , Nairobi , Kenya
3: International Rice Research Institute (IRRI) , Los Baños, Philippines

2. 2
Motivation
Worldwide, agriculture is responsible for 47 and 84 % of anthropogenic
CH4 and N2O emissions, respectively (Smith et al 2007, IPCC WG III)
Smallholder farms are crucial in e.g. Sub-Saharan Africa
75 % of both agricultural and job production (Africa Development Bank 2010)
80 % of farms in SSA are smaller than 2 ha (FAO 2010)
Yields are low (ca. 1 Mg ha-1)
Evidence-based data of GHG emissions in smallholder farms is scarce
Source: Rosenstock et al. 2016. D.O.I. 10.1007/978-3-319-29794-1_1

3. 3
Chamber methods for measuring GHG fluxes
in terrestrial ecosystems
Pros
+ Simple, no in-situ analyzers needed
+ Allow for treatment-plots experiments
+ Existence of protocols
Cons
- Change in the soil environmental conditions
- Spatial and temporal variability of fluxes
- Accuracy and reliability of measurements

4. 4
Chamber
Placement
Terrain
Soil
Vegetation
Management
Logistics
•Depressions/ ridges/ slope
(deposition/ erosion, depth to
groundwater) / aspect
•Paths (bulk density)
•Stones/ terraces (management)
•Color (SOC/ flooding)
•Texture (water/ nutrient availab.)
•Compaction/Plough pan (bulk
density)
•Natural (vegetation layers/ patchiness,
species, coarse woody
materialnutrient/ water availability)
•Row crops (row/ interrownutrient/
water availability)
•Intercropping (nutrient/ water
availability)
•Irrigation/ flood water inlet/outlet
(soil processes)
•Fertilization (water/ nutrient
availab.)
•Compaction/Plough pan (bulk
density)
•Accessibility
•Change of soil properties along
access paths
•Interference with management

5. 5
Gas
sampling
Monitor
Timing
& interval
Vials
Sampling
Storage
•Crop performance in/ outside
chamber
• Animal activity (e.g. ants, termites,
earthworms)
•Chamber seals/ maintainance
•Approx. at average daily soil-T (e.g.
morning 9-11)
•Minimize closure time (determine
minimum detectable flux) to
minimize chamber effects on soil
environmental conditions
•Flushing (min. 2x volume) or use
pre-evacuated vials
•Overpressurize
•Logical numbering
•Minimize disturbance at the plot
(plant cover/ soil compaction)
•Flush syringe
•Ensure headspace mixing
•Check seal tightness
•Determine max. storage time
•Use standards for comparison
•Store vials in boxes

6. 6
Gas analysis
and data
processing
Responsibility
Measurement
instrument
Flux
calculation
Maintenance
Reporting
•Hierarchy of responsibility
(instrument maintenance/ analysis/
data storage/ reporting)
•Understand principles
•Optimize sensitivity in terms of
accuracy & precision
•Coefficient of variation for repeated
concentration measurements (e.g. N
=5) <1%
•Check relationship between
instrument signal and concentration
•Linear or non-linear (understand
advantages and disadvantages of
both)
•Calculate detection limits
•If slope of regression = 0 (check p-
value of slope)  flux = 0
•Stock spare parts
•Check & service instrument
regularly
•Clean environment
•Do flux calculations immediately
•Report back problems to sampling
team (e.g. numbering/ unusual
noise in concentration changes
across sampling interval
•Check logic of fluxes with
observations of auxilliary
measurements

7. 7
Auxilliary
Measurements
& Reporting
Socio-
economy
Meteorology
Soil
properties
Soil hydrology
Crop/ plant
performance
•Precipitation
•Air temperature
•Photosynthetic active radiation
•Wind speed/ direction
•Relative humidity
•Evapotranspiration rates
•Soil-temperature/ moisture
(different layers down to 1m if
possible)
Multi-layer (0-10, 10-20, 20-50, 50-
100 cm)
•Texture/ SOC/ total N / inorganic
N/ bulk density/ pH
•Water saturated conductivity
•Microbial biomass C and N
•Litter type / depth / C and N
content (if applicable)
•Water infiltration / hydraulic
conductivity / water holding capacity
•Distance to groundwater
•Floodwater depth (e.g. rice paddies)
•Depth of drainage tiles
•Biomass development (monthly)
•Pests/ diseases/ weeds
•Development stages (e.g. tillering/
flowering)
•LAI
•Harvest index
•Yield / N content
Management
•Field operations (e.g. ploughing,
seeding, weeding, fertilization,
irrigation, harvesting, pesticide
applic.)
•Fertilizer types & amounts
•Crop type / rotation, variety and
planting density
•Residue management

8. 8
Spatial and temporal variability of soil GHG fluxes
Source: Barton et al. 2015,
Scientific Reports,
D.O.I. 10.1038/srep15912
Source: Cowan et al. 2015,
Biogeosciences,
D.O.I. 10.5194/bg-12-1585-2015

9. 9
Chamber 1
The gas pooling technique
Arias-Navarro et al. 2013, Soil Biol Biochem, D.O.I. 10.1016/j.soilbio.2013.08.011
Close
Mixing of the gas sample
Pressurize/ Expand
T0
Inject, flush &
overpressurize
glass vial
T0
T0
T1T2T3
T2 T1T3
Gas Chromatograph

10. 10
Chamber-based methods are recommended in complex
landscapes such as smallholder agriculture.
Spatial and temporal variability remains a huge challenge
 adequate design and sampling frequency are crucial.
QA/QC is essential at all steps.
Chamber design and positioning
Gas sampling and analysis
Calculations and reporting
Conclusions
Voice: David Pelster, Klaus Butterbach-Bahl & Allison Kolar