1. Effect of the ACN on agricultural field water balance in Mali K. Brannan, R. Kablan, R.S. Yost, M.D. Doumbia, A. Yoroté, Y. Toloba, S. Sissoko, and M. Vaksman

2. Overview Background Hypothesis Calculation Methods Results Future Plans (This was 1 st year)

3. Background (Problems) Deforestation Reduced Soil Fertility Farming on Steep Slopes Runoff Management $Revenue Sources$ Reduced Groundwater Recharge

4. Background (Runoff Management, Mali)

5. Practice: Amenagement en courbes de niveau (ACN) Field Water management practice Series of ridges contour Permanent Ridge (Ado) Temporary Ridges (cropped areas) Water management of whole area Socio-economic factors

6. Impact of Practice No ACNwith ACN

7. Hypothesis ACN improves field water balance More water available for crop use More potential local groundwater recharge (drainage) Reduces surface runoff

8. Approach Two Locations (Konkgougou and Fransirokoro) Treatments: Field with ACN and without Measure Soil Water at multiple locations and depths Rainfall and potential evaporation data Calculate field water balance

9. Soil Water Probe Diviner 2000®, Sentek

10. Study Site: Konkgougou Tubes Permanent Ridges

11. Field Water Balance

12.  S = R – ET – E soil – GWR – RO where,  S - change in soil water storage R - rainfall ET - crop evapotranspiration E soil - evaporation from the soil GWR - local groundwater recharge RO - surface runoff Measured Estimated Calculated

13. Field Water Balance: Runoff RO = R – ET – E soil – GWR –  S

14. Rainfall and Evaporation Rainfall data collected at site Potential Evaporation data from Bamako Station Soil evaporation constant proportion of potential evaporation

15. ET Calculation ET c - Crop evapotranspiration K c - crop coefficient ET o - observed (reference crop) ET (K c temporally distributed based on LAI)

16. ET Calculation

17. Soil Moisture Storage Integrate Readings

18. Soil Moisture Storage

19. Local Groundwater Recharge (Drainage) Pedo-transfer function Van Genutchen’s Equation –Hydraulic potential –Hydraulic conductivity Darcy’s Equation

20. Local Groundwater Recharge Aggregate

21. Local Groundwater Recharge Cumulative Local Groundwater Recharge Unsaturated Hyd Cond.

22. Runoff RO = R – ET – E soil – GWR –  S

23. Results Comparisons tubes with and without ACN –Tubes 03 to 10 –Tubes 05 to 10 –Tubes 15 to 21 –Tubes 17 to 22

24. Results: Tubes 03 to 10

25. Results: Tubes 05 to 10

26. Results: Tubes 15 to 21

27. Results: Tubes 17 to 22

28. Location Effect Ados Tube 05 Tube 17 Water Accumulates

29. Future Plans Continue data collection (several more years) Relate balance to crop yields Improve instrument calibration Improve calculation methods Quantify impact on village wells Improve/Modify ACN design

30. Merci