1J. Macedo, 2M. Souvanhnachit, 3S. Rattanavong, 4B. Maokhamphiou, 4T. Sotoukee, 4P. Pavelic, 1M. Sarkis, 1T. Downs   1 Department of International Development, Community, and Environment, Clark University, Worcester, MA. U.S.A. 2 Department of Water Resources Engineering, National University of Laos, Vientiane, Lao PDR 3Independent Consultant, Washington DC, U.S.A. 4 International Water Management Institute Vientiane, Lao PDR.   Climate change risks pose significant challenge to smallholder irrigators who rely on rainfed agriculture for their livelihoods. Increased mean surface temperatures, varying rainfall, increasing evaporation and declining soil moistures all serve to impact productivity. Groundwater irrigation poses promising potential for agricultural productivity and the livelihoods of smallholders. Groundwater irrigation for agriculture use requires constant water quality monitoring. This excerpt is part of a field research, which assessed the impacts of biochar and fertilizer treatments on soil nutrients status, soil moisture, irrigation groundwater quality for agricultural use on the growth and yield of water spinach (Ipomoea aquatica). Groundwater quality was monitored to determine the levels of electric conductivity (EC) and total dissolved solids (TDS) determinants of salinity and sodium, calcium, and magnesium to calculate the sodium absorption ratio (SAR) to estimate sodicity. The methods involved daily field tests to measure EC, TDS, pH, temperature, and detailed chemical analysis. The results indicate that the mean EC (0.021 dS/m; SD = 0.010) is significantly less than the salinity tolerance threshold for water spinach (< 1.3 dS/m) and the mean TDS (12 ppm; SD = 4.5) with soil pH of 6.6. The results suggest that the irrigation groundwater quality was suitable for agriculture and the chance of salinity was significantly low. The computed SAR 0.174 was significantly lower than the normal level (<10) above which soil water permeability could result from sodic soil condition. The results demonstrate that groundwater use for agriculture could assist smallholders adapt to climate change risks, but judicious use requires constant monitoring of groundwater quality and resources to increase crop yield and improve soil health.   Key Words: Salinity, Sodicity, Groundwater Quality, Electric Conductivity, Total Dissolved Solids, Sodium Absorption Ratio This PowerPoint only focuses on assessing irrigation groundwater quality in objective 4 and not the water use efficiency aspect/soil water savings. Here, we are only interested in the ability for biochar to reduce soil water salinity and sodicity.

1. Irrigation Groundwater Quality for Agricultural Usability
in Biochar and Fertilizer Amendments among Smallholders
Irrigators in Ekxang Village, Vientiane Province, Lao PDR
Jenkins Macedo, Mixay Souvanhnachit, Sengsamay Rattanavong,
Bounmee Maokhamphiou, Touleelor Sotoukee,
Dr. Paul Pavelic, Dr. Marianne Sarkis, Dr. Timothy J. Downs
Presented at:
Hydrology Research Conference
Department of Geography
Clark University
Worcester, MA. U.S.A.
December 2, 2014

2. Abstract
Irrigation Groundwater Quality for Agricultural Usability in Biochar and Fertilizer Amendments
among Smallholders Irrigators in Ekxang Village, Vientiane Province, Lao PDR
1
J. Macedo, 2
M. Souvanhnachit, 3
S. Rattanavong, 4
B. Maokhamphiou, 4
T. Sotoukee, 4
P. Pavelic, 1
M. Sarkis, 1
T. Downs
1
Department of International Development, Community, and Environment, Clark University, Worcester, MA. U.S.A.
2
Department of Water Resources Engineering, National University of Laos, Vientiane, Lao PDR
3
Independent Consultant, Washington DC, U.S.A.
4
International Water Management Institute Vientiane, Lao PDR.
Climate change risks pose significant challenge to smallholder irrigators who rely on rainfed agriculture for their livelihoods. Increased mean surface temperatures,
varying rainfall, increasing evaporation and declining soil moistures all serve to impact productivity. Groundwater irrigation poses promising potential for agricultural
productivity and the livelihoods of smallholders. Groundwater irrigation for agriculture use requires constant water quality monitoring. This excerpt is part of a field
research, which assessed the impacts of biochar and fertilizer treatments on soil nutrients status, soil moisture, irrigation groundwater quality for agricultural use on the
growth and yield of water spinach (Ipomoea aquatica). Groundwater quality was monitored to determine the levels of electric conductivity (EC) and total dissolved solids
(TDS) determinants of salinity and sodium, calcium, and magnesium to calculate the sodium absorption ratio (SAR) to estimate sodicity. The methods involved daily
field tests to measure EC, TDS, pH, temperature, and detailed chemical analysis. The results indicate that the mean EC (0.021 dS/m; SD = 0.010) is significantly less
than the salinity tolerance threshold for water spinach (< 1.3 dS/m) and the mean TDS (12 ppm; SD = 4.5) with soil pH of 6.6. The results suggest that the irrigation
groundwater quality was suitable for agriculture and the chance of salinity was significantly low. The computed SAR 0.174 was significantly lower than the normal level
(<10) above which soil water permeability could result from sodic soil condition. The results demonstrate that groundwater use for agriculture could assist smallholders
adapt to climate change risks, but judicious use requires constant monitoring of groundwater quality and resources to increase crop yield and improve soil health.
Key Words: Salinity, Sodicity, Groundwater Quality, Electric Conductivity, Total Dissolved Solids, Sodium Absorption Ratio
09/10/15
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3. Research Objectives
o To evaluate whether or not rice husk
biochar inoculated with cow manure,
manure tea, and NPK amended in soil
increase soil nutrient status and improve
crop yields relative to the traditional
farming practice.
o To assessed the potential of biochar to
improve soil water availability.
o To evaluate the costs and benefits of
treatments relative to productivity.
o *To assess irrigation groundwater
quality and crop water use efficiency
for agricultural productivity.
Note: *This excerpt is focus on a section of objective 4: “Irrigation groundwater quality for agricultural use.” 09/10/15
3

4. Scientific Background & Context
o Scientific consensus of anthropogenic-induced
greenhouse gases emissions (IPCC, 2013).
o Climate change variability increased mean surface
temperature, inconsistent precipitation event, persist
drought, reduced soil moisture and decreases in
productivity (Brown & Funk, 2008; Lal, 2009b;
Gregory et al., 2005).
o Sustainable groundwater irrigation for agricultural use
pose a promising potential in drought-induced
ecosystems (Pavelic et al.,2010).
o Judicious use of groundwater resources for agriculture
requires constant monitoring of water quality for
salinity and sodicity (Ayers & Westcot, 1976; Fipps,
2003; Hanson et al., 2006).
o Monitoring irrigation groundwater quality is essential
to reduce soil salinity and sodicity to enhance crop
growth, relative potential yield, soil water availability,
and soil health (Ayers & Westcot, 1976; Hanson et al.,
2006; Fipps, 2003). 09/10/15
4

5. Source: T. Sotoukee/GIS-IWMI Groundwater Project, 2014
Ekxang Village Land Use Map
09/10/15
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6. Ekxang village Water Resources
Source: T. Sotoukee/GIS-IWMI Groundwater Project, 2014 09/10/15
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7. Soil Physical Characteristics
Source: T. Sotoukee/GIS-IWMI Groundwater Project, 2014 09/10/15
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8. Soil Texture Classification
Empirically determined using the Visual Soil Assessment approach (Shepherd et al., 2008) and the USDA Soil Texture
Calculator http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/survey/?cid=nrcs142p2_054167 09/10/15
8
Silty Clay (10%
sand, 50 clay &
40% silt

9. Topography
Source: T. Sotoukee/GIS-IWMI Groundwater Project, 2014 09/10/15
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10. Salinity & Sodicity Problems in Agricultural
Water Quality
Source: Fipps, 2003. “Irrigation Water Quality Standards and Salinity Management
Strategies.” Agricultural Communications at the Texas A&M University System, Houston, TX.
U.S.A.
09/10/15
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11. Irrigation Water Salinity Tolerance Levels of Some
Major Vegetables
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12. Sodium Hazard Recommended Levels
Source: Fipps, 2003. “Irrigation Water Quality Standards and Salinity Management
Strategies.” Agricultural Communications at the Texas A&M University System, Houston, TX.
U.S.A.
09/10/15
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13. Materials & Methods
A. Salinity
a. Daily water quality field-based tests (70 days)
o Electric Conductivity (dS/m)
o Total Dissolved Solids (ppm)
o pH
o Temperature (°F)
b. Soil salinity determination
o 0-15cm (5 grams each (15) soil solution)*
o 15-30cm (5 grams each (15) soil solution)*
B. Sodicity
a. Detailed Chemical Analyses (Lab)
o Sodium (Na meq/L)
o Calcium (Ca meq/L)
o Magnesium (Mg meq/L)
09/10/15
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*Each soil sample was thoroughly mixed in distilled water and the solution used to
measure EC, TDS, and pH with the HI 98 129 multi-parametric tester.

14. 09/10/15
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15. Crop Water Use Efficiency & Monitoring
Note: Data sample 09/10/15
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16. Irrigation Groundwater Quality Testing
Note: Data sample 09/10/15
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17. Laboratory Analysis of Groundwater
Sample (1500ml)
09/10/15
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18. Analysis & Results
Parameters
Chemical
Symbols
Lab
Results
(mq/L)
Atomic
Weights
(AW)
Valences
(V)
Converted
to (meq/L) ppm
Sum of
Cation
(meq/L
) pH SAR
EC
(dS/m)
TDS
(ppm)
Calcium Ca 12.40 40.01 2 0.620 12.40 0.515 6.6 0.174ns
0.021ns
12
Magnesium Mg 2.95 24.31 2 0.243 2.95 <10 <1.3
Sodium Na 7.41 22.99 1 0.322 7.41 RTh Values
Potassium K 4.10 39.10 1 0.105 4.10
Bicarbonate HCO3
2-
7.40 61.02 1 0.121 7.40
Sulphate SO4 45.70 96.06 2 0.951 45.70
Chloride Cl 1.77 35.45 1 0.050 1.77
Nitrate Nitrogen NO3-N 0.18 76.01 24 0.058 0.18
Ammonium Nitrogen NH4-N 0.21 32.00 8 0.054 0.21
Ortho-Phosphate PO4-P 0.24 126.00 3 0.006 0.24
ns = impact not significant
RTh = Recommended Thresholds Values
09/10/15
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19. Soil Salinity Measurement from Bulk Density Soil Samples
09/10/15
Soil Sample
Depth (cm)
ECe
(dS/m)
TDS
(ppm)
TDS
(dS/m)
0-15 0.025 10.000 0.016
15-30 0.018 8.000 0.013
0-15 0.024 15.000 0.023
15-30 0.020 10.000 0.016
0-15 0.030 10.000 0.016
15-30 0.022 7.000 0.011
0-15 0.030 20.000 0.031
15-30 0.025 15.000 0.023
0-15 0.032 21.000 0.033
15-30 0.023 20.000 0.031
Sum 0.249 136.000 0.213
Mean (0-15) 0.028 15.200 0.024
Mean (15-30) 0.022 12.000 0.019
STDEV 0.005 5.317 0.008
Grand Mean 0.025 13.600 0.021
0-15 0.030 15.000 0.023
15-30 0.020 12.000 0.019
0-15 0.028 19.000 0.030
15-30 0.020 16.000 0.025
0-15 0.030 20.000 0.031
15-30 0.023 16.000 0.025
0-15 0.040 24.000 0.038
15-30 0.018 13.000 0.020
0-15 0.025 18.000 0.028
15-30 0.019 10.000 0.016
Sum 0.253 163.000 0.255
Mean (0-15) 0.031 19.200 0.030
Mean (15-30) 0.020 13.833 0.022
STDEV 0.007 4.138 0.006
Grand Mean 0.025 16.300 0.025
0-15 0.017 20.000 0.031
15-30 0.013 15.000 0.023
0-15 0.015 22.000 0.034
15-30 0.019 18.000 0.028
0-15 0.011 17.000 0.027
15-30 0.015 12.000 0.019
0-15 0.016 14.000 0.022
15-30 0.018 12.000 0.019
0-15 0.018 20.000 0.031
15-30 0.016 15.000 0.023
Sum 0.158 165.000 0.258
Mean (0-15) 0.015 18.600 0.029
Mean (15-30) 0.016 14.400 0.023
STDEV 0.002 3.472 0.005
Grand Mean 0.016 16.500 0.026
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Pre-Treatment Treatment Post - Treatment
Pre-TreatmentTreatmentPost-Treatment

20. The Experimental Units
09/10/15
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21. Discussions & Conclusions
o The levels of salinity (0.021 dS/m < 1.3 dS/m) and sodicity
(SAR 0.174 < 10) were relatively lower than their respective
recommended thresholds suitable for agricultural use.
o Significant reduction in soil salinity by depth can be attributed
to biochar addition.
o The levels of EC, TDS and pH increased due to precipitation
and surface runoff and decreased due to irrigation and
groundwater recharge.
o Groundwater quality changes over time and space, but is
subject to precipitation, irrigation systems, surface runoff, and
temperature.
o Field test should be holistic and include daily measurements of
other potential pollutants.
o Sustainable groundwater irrigation poses a promising
potential to enhance agricultural productivity in hot and dry
terrestrial ecosystems.
o Agricultural water use efficiency and water quality need to be
constantly monitored locally through participatory
engagement of smallholders in the monitoring process.
09/10/15
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22. Agricultural Groundwater Policy
Implications
o Groundwater quality assessment for agricultural use should be
integrative and locally accessible to smallholders.
o Irrigation infrastructures should resonate with the needs and resources
of smallholders’ irrigators to foster maintenance and sustainability.
o Local, regional or provincial, state and non-state actors should invest in
smallholder irrigation infrastructures to enhance sustainable
groundwater usability and efficiency.
o Sustainable groundwater irrigation for agricultural use should be
equipped with monitoring stations to determine water quality for early
detection of potential pollutants and their sources.
o Smallholders should be engaged in policy formulations for sustainable
groundwater irrigation to promote ownership and systems
sustainability.
o Agricultural extension services should be sensitive to local irrigation
regimes, education, training, and the provision of resources to
smallholders.
o Smallholders are willing to adapt to new irrigation infrastructures, but
fear of failure due to financial insecurity should they attempt to change
their current agricultural irrigation systems to more efficient
alternatives.
09/10/15
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23. Bibliography
Ayers, R. S. and D. W. Westcot. 1976. Water Quality for Agriculture. FAO, Rome, Italy.
Brown, M. E. & C. C. Funk. 2008. Food Security Under Climate Change. Science 319:580-581.
Charcoal Remedies. The Biochar Revolution,http://www.charcoalremedies.com/charcoaltimes/0512/biochar_revolution. Accessed:
11/20/2013
Fipps, G. 2003. Irrigation Water Quality Standards and Salinity Management Strategies. Agricultural Communications at the Texas
A&M University System, Houston, TX. U.S.A.
Gregory, P. J., J. S. Ingram, and M. Brklacich. 2005. Climate Change and Food Security. Philosophical transactions of the Royal Society
of London. Series B, Biological sciences 360:2139-2148.
Hanson, B. R., S. R. Grattan, and A. Fulton. 2006. Agricultural Salinity and Drainage. Water Management Series Publication:1-180.
IPCC. 2013. Summary for Policymakers. Intergovernmental Panel on Climate Change, New York City, NY.
Lal, R. 2009b. Soil Degradation as a Reason for Inadequate Human Nutrition. Food Security 1:45-57.
Pavelic, P., C. T. Hoanh, M. McCartney, G. Lacombe, D. Suhardiman, K. Srisuk, and Y. Kataoka. 2010. Enhancing the Resilience and
Productivity of Rainfed Dominated Systems in Lao PDR through Sustainable Groundwater Use. International Water Management
Institute, Vientiane Capital, Lao PDR.
Shepherd, G., F. Stagnari, M. Pisante, and J. Benites. 2008. Visual Soil Assessment Field Guides. Food and Agriculture Organization of
the United Nations, Rome, Italy.
09/10/15
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24. Special Thanks
Staff, Center of Global Food Security/USAID, Purdue University,
West Lafayette, IN., U.S.A.
Faculty, Environmental Science & Policy, IDCE/Clark University,
Worcester, MA., U.S.A.
Staff, International Water Management Institute,
Vientiane Capital, Lao PDR.
Faculty & Students, Water Resources and Engineering, National University of Laos,
Vientiane Capital, Lao PDR.
Chief Administrator, International Rice Research Institute,
Vientiane Capital, Lao PDR.
Staff, Office of Sponsored Research and Programs, Clark University,
Worcester, MA., U.S.A.
Staff, International Development, Community, and Environmental Travel Grant,
Clark University, Worcester, MA., U.S.A.
Administrators, District & Provincial Agricultural & Forestry Extension Office,
Vientiane Province, Lao PDR.
Staff, Soil Laboratory, National Agricultural and Forestry Research Institute,
Vientiane Capital, Lao PDR.
Staff, Water Laboratory, Department of Irrigation,
Vientiane Capital, Lao PDR.
Academic and Research Advisors at Clark University and IWMI
Independent Consultant, Lao Translation Services
Washington, D.C., U.S.A. 09/10/15
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