Irrigation Water Management

1. Irrigation Water Management An essential ingredient of irrigation system • design • operation VERY important when applying animal waste

2. John Busch Irrigation Engineer USDA-NRCS 3990 Midway Lane Baker City, OR 97814 541-523-7121 ext 111 john.busch@or.usda.gov

3. Basic IWM concepts • WHEN to irrigate ?? • HOW MUCH water to apply ?? • HOW MUCH is applied??

4. Irrigation Water Management How important ??? Improper IWM can cause INUNDATION!

5. Irrigation Water Management How important ??? Improper IWM can leave one HIGh & DRY!

6. Important Point….. Errors in the timing and amount of irrigation applications can be PROBLEMATIC Potential problems can increase when applying animal waste through an irrigation system

7. NRCS IWM Job Sheet Available on the Oregon NRCS Engineering Web Site

8. IWM Plan Specifications An IWM Plan shall be developed to assist the irrigator or decision-maker in the proper management and application of irrigation water. Factors to be included in the IWM Plan include the following: • Statement of objective(s) for the IWM Plan • Description of the irrigation system and its components including water supply, water conveyance and application systems, and any water measurement devices. • Soils information including available water capacity, depth, and limiting conditions related to irrigation water management. • Crop information including crops grown, irrigation water requirements, and physical characteristics including rooting depth. • Description of irrigation scheduling and system management including methods for measuring and/or estimating crop water use and soil moisture levels. • IWM record keeping requirements of appropriate detail for the IWM objectives. The detail of IWM may be specified as Detailed orBy Irrigation Cycle with the associated level of record keeping as appropriate for the level of detail. • IWM review requirements regarding the effectiveness of the IWM Plan and its implementation.

9. NRCS IWM Plan Specifications • Statement of objective(s)for the IWM Plan • Description of the irrigation system and its components • Soils information including available water capacity, depth, and limiting conditions • Crop information including crops grown, irrigation water requirements, and physical characteristics

10. NRCS IWM Plan Specifications • Description of irrigation scheduling and system management • IWM record keeping requirements of appropriate detail • IWM review

11. IWM Objectives Work with cooperator to • Identify needs • Specify objectives to meet needs Cooperator involvement is important ! buy-in from the beginning

12. Irrigation System • Irrigation system characteristics

18. Includes Big Guns

19. Irrigation System • System type • Operating characteristics Coefficient of Uniformity (CU) data or distribution uniformity (DU) shall be used in selecting sprinkler spacing, nozzle size, and operating pressure For pivots: Min CU = 85% Fixed-Solid-set, Big Gun and Periodic Move Sprinkler: Min CU = 75 % for deep-rooted crops (4 ft +) Min CU = 85 % for shallow-rooted crops

20. Irrigation System • Water Source(s) • Available flow rate and total amount • Water Quality • Salts (Sodium) • Chemicals (Boron)

21. Soils Information Including • Soil characteristics • Physical data – depth, limitations, AWC • Soil chemistry – EC, SAR

22. Soils Information

23.  ET Infiltation  Water balance in root zone  Applied water Precipitation  Runoff  Root zone -- Water storage Deep perc (leaching)   Capillary rise

24. SoilParticles Available Water Gravitational Water Unavailable Water Soil-water basics Field Capacity Saturated Condition

25. Field Capacity FC Available Water Capacity AWC Management Allowed Deficit MAD

26. Flocculation is important because water moves mostly in large pores between aggregates. Also, plant roots grow mainly between aggregates.

27. In all but the sandiest soils, dispersed clays plug soil pores and impede water infiltration and soil drainage.

28. Dispersion and surface sealing Soils Information Dispersion and surface sealing from sodium

29. Crop Information • Crops grown • Irrigation water requirements • Rooting depth • Other physical characteristics

30. Scheduling & System Management • Check actual soil moisture levels • Know the amount of irrigation water applied • Know irrigation guidelines for crops grown • Track crop water use – evapotranspiration

31. Estimate CU • Monthly estimate from regional weather data • Daily estimate from regional or on-site data • Measure applied water • Farm delivery • Field application Soil Water Reservoir • Measure soil water • Field probe + feel • Instrumentation

32. Three elements for IWM ESSENTIAL • Estimate or measure soil moisture • Measure irrigation water applied • Estimate crop consumptive use  Need ALL 3 items

33. Implementing IWM • Knowledge of fields, crops, irrigation system • Effective IWM requires judgment, observation, and local knowledge • Use ALL available information  proceed cautiously, test, observe NO one knows the farm as well as the manager !

34. Scheduling & System Management • Check actual soil moisture levels • Know the amount of irrigation water applied • Know irrigation guidelines for crops grown • Track crop water use – evapotranspiration

35. IWM Records • Date and duration of each irrigation • Water applied in each irrigation • Dates and amounts of effective rainfall • Crop water use • Daily evapotranspiration • Water use estimate between irrigations • Soil moisture status

36. IWM Review • Notes on how well IWM goals were met • Description of crop response to IWM Plan • Observations of soil erosion, etc. • Notes on water/environmental quality issues (Relate to CNMP) • Notes on irrigation system operations and maintenance

37. Thoughts, Questions, Comments??

39. NRCS IWM Plan Specifications • Description of irrigation scheduling and system management • IWM record keeping requirements of appropriate detail • IWM review

40. Implementing IWM • Knowledge of fields, crops, irrigation system • Effective IWM requires judgment, observation, and local knowledge • Use ALL available information  proceed cautiously, test, observe NO one knows the farm as well as the manager !

41.  ET Infiltation  Water balance in root zone  Applied water Precipitation  Runoff  Root zone -- Water storage Deep perc (leaching)   Capillary rise

42. Infiltation  Water balance in root zone   Applied water Precipitation ET  Runoff (erosion)  Root zone -- Water storage (Check uniformity) Deep perc (leaching)   Capillary rise

43. System management    • Rainfall -- measure • ET --  measure/estimate • Soil water --  measure/estimate • Application --  measure/estimate Infiltration --  measure/estimate • Runoff --  measure/estimate    

44. Conclusion     CANNOT depend on measuring/estimating only ONE parameter    

45. Estimate CU • Monthly estimate from regional weather data • Daily estimate from regional or on-site data • Measure applied water • Farm delivery • Field application Soil Water Reservoir • Measure soil water • Field probe + feel • Instrumentation

48. Irrigation System • System type • Operating characteristics Coefficient of Uniformity (CU) data or distribution uniformity (DU) shall be used in selecting sprinkler spacing, nozzle size, and operating pressure For pivots: Min CU = 85% Fixed-Solid-set, Big Gun and Periodic Move Sprinkler: Min CU = 75 % for deep-rooted crops (4 ft +) Min CU = 85 % for shallow-rooted crops

49. Irrigation System • System type • Operating characteristics Coefficient of Uniformity (CU) data or distribution uniformity (DU) shall be used in selecting sprinkler spacing, nozzle size, and operating pressure For pivots: Min CU = 85% Fixed-Solid-set, Big Gun and Periodic Move Sprinkler: Min CU = 75 % for deep-rooted crops (4 ft +) Min CU = 85 % for shallow-rooted crops