2. Background of Study Previous Study without APLTV At 0% slope: Highest CU = 71% Highest DU = 53.5 % Much lower DU and CU under sloping conditions Recommmended the use of pressure regulators

3. OBJECTIVE To determine the effect of using Adjustable Pressure-Loss Lateral Takeoff Valves (APLTVs) on water distribution uniformity of a low-cost drip irrigation system under sloping conditions

4. METHODOLOGY 100 sq. m IDE Easy drip kit (10 m x 10 m) Submain Slopes: 0%, 10%, 20%, 30%, (S l = 0%) Average Operating Pressure Head: 0.5 m, 1.0 m and 1.5 m Sampled from 11 emitters per lateral for a total of 110 samples Direct volumetric measurement for emitter discharge 3 trials per setting Sampling protocols developed by Dr. Jack Keller

5. Experimental Set-up College of Engineering & Agro-industrial Technology, University of the Philippines Los Baños

6. Experimental Set-up College of Engineering & Agro-industrial Technology, University of the Philippines Los Baños

7. The APLTV College of Engineering & Agro-industrial Technology, University of the Philippines Los Baños

8. Sampling and Data Collection

11. Evaluation of Water Distribution Uniformity Christiansen’s Coefficient of Uniformity where: CU = coefficient of uniformity (%) q = emitter discharge M = average of discharge values

12. Evaluation of Water Distribution Uniformity Merriam and Keller’s Emission Uniformity EU = (q LQ /q mean )100 where: EU = emission uniformity (%) q LQ = average of the lowest quarter of the observed discharge values q mean = average of observed discharge values

13. RESULTS

14. Average Emitter Discharge Slope (%) without APLTV Adj with APLTV Adj Average Pressure Head (m) 0.511.50.511.5 103.434.655.973.354.855.51 203.304.766.252.613.824.03 303.134.896.082.553.434.06 Q unit in lph

15. Maximum Emitter Discharge Slope (%) without APLTV Adj with APLTV Adj Average Pressure Head (m) 0.511.50.511.5 10 6.056.477.404.476.626.85 20 6.047.479.073.615.016.05 30 6.148.059.093.545.256.11 Q unit in lph

16. Minimum Emitter Discharge Slope (%) without APLTV Adj with APLTV Adj Average Pressure Head (m) 0.511.50.511.5 10 1.542.623.180.873.523.88 20 0.111.373.341.311.961.08 30 0.001.010.841.101.861.70 Q unit in lph

17. Coefficient of Uniformity (CU)

23. Distribution Uniformity (DU)

29. Summary of t-tests for CU @ alpha=5% SlopeHeadP-valueRemarks 10%0.50.0429significant improvement 10.0052significant improvement 1.50.0036significant improvement 20%0.50.0022significant improvement 10.0048significant improvement 1.50.0629no improvement 30%0.50.0006significant improvement 10.0025significant improvement 1.50.0090but no improvement

30. Summary of t-tests for DU @ alpha=5% SlopeHeadP-valueRemarks 10%0.50.0459significant improvement 10.0101significant improvement 1.50.0337significant improvement 20%0.50.0025significant improvement 10.0025significant improvement 1.50.0100but no improvement 30%0.50.0013significant improvement 10.0002significant improvement 1.50.0697no improvement

31. CONCLUSION  Water distribution uniformity of the 100 sq m microtube type drip irrigation system generally increases significantly with the use of APLTVs  CU and DU generally increase with increasing head and increasing slopes  CU and DU can not be further improved by APLTVs at a head of 1.5 m for steep slopes  Extremely low and high emitter discharge value are avoided with APLTVs  In general, the inclusion of APLTVs as a built-in component of the low-cost drip irrigation system can potentially increase crop yield and productivity

32. Acknowledgements This project was funded by the International Development Enterprises (IDE) in collaboration with the USAID- funded SANREM-CRSP Paper presentation was made possible through the support from DA-BAR Prof. Arthur Fajardo, Rafael Padre and everyone who helped in data gathering

33. Thank You! Dr. Victor B. Ella Professor Land and Water Resources Division Institute of Agricultural Engineering College of Engineering and Agro-industrial Technology University of the Philippines Los Banos College, Laguna, PHILIPPINES E-mail: vbella@up.edu.ph orvbella@up.edu.ph vbella100@yahoo.com Tel/fax: (049)-536-2873