How to improve irrigation scheduling using soil moisture
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The document discusses methods to improve irrigation scheduling using soil moisture monitoring to enhance crop health while minimizing costs and environmental impact. It outlines various techniques such as using calendar methods, soil moisture measurement, plant measurements, and atmospheric data to determine when to irrigate. The author emphasizes that soil moisture monitoring, combined with new sensor technology, offers the best insights for managing irrigation effectively.
![“Since the soil is the primary recipient of
the irrigation water, it seems reasonable that
the answers to these two questions [when
to turn water on and when to turn it off]
should come from monitoring the soil.”
Dr. Melvin D. Campbell](https://image.slidesharecdn.com/gscampbellhowtoimproveirrigationschedulingusingsoilmoisture-final-190731164544/85/How-to-improve-irrigation-scheduling-using-soil-moisture-11-320.jpg)
How to improve irrigation scheduling using soil moisture
- 2. HOW TO IMPROVE IRRIGATION SCHEDULING USING SOIL MOISTURE GAYLON S. CAMPBELL, PH.D. METER GROUP, INC. USA PULLMAN, WA, USA
- 3. WHY MANAGE IRRIGATION? • Produce healthy crops while minimizing costs and environmental impact • Control assimilate partitioning and increase value of harvested products • Other custom applications (frost control, nutrient management, waste disposal, etc.)
- 4. CORRECT IRRIGATION REQUIRES THE ANSWER TO ONLY TWO QUESTIONS: • When do I turn the water on? • When do I turn the water off?
- 5. OPTIONS FOR DECIDING WHEN TO TURN THE WATER ON • Clock or calendar • Ask the soil • Ask the plant • Ask the atmosphere
- 6. IRRIGATION SCHEDULING BY CLOCK OR CALENDAR Method: • Apply water on a fixed schedule • Simplest of all methods • Match average supply with average demand But: • Wastes water and nutrients when demand is low • Stresses crops when demand is high
- 7. IRRIGATION SCHEDULING USING SOIL MOISTURE MEASUREMENT Method: • Install sensors • Determine full and refill points • Monitor Shows water applications and extraction Can show drainage But: • Soils and crops are variable • Can’t cover the field with sensors • Doesn’t measure the stress level of plants
- 8. IRRIGATION SCHEDULING BASED ON PLANT MEASUREMENT Method: • Measure canopy temp., stomatal cond., stem diam., fruit diam, water potential, etc. • Irrigate when the plant says it needs it Essential for deficit and controlled stress irrigation But: Water stress from: • Too little water • Too much water • Disease • High evap. demand Irrigation can only fix too little water
- 9. IRRIGATION SCHEDULING USING ET (ATMOSPHERE) • Method: • Make a water budget • Measure weather • Estimate ET • Irrigate to replenish ET • Corrects for demand • Relatively easy and inexpensive But: • How much water was actually applied? • How much was actually used? • Did water drain out the bottom?
- 10. WHICH METHOD IS BEST? • Depends on needs and resources • Go beyond calendar for modern irrigated agriculture • Soil moisture monitoring gives best understanding and control • ET can give insight into varying demands and can be effectively used with soil measurements • Plant measurements essential for controlled stress irrigation
- 11. “Since the soil is the primary recipient of the irrigation water, it seems reasonable that the answers to these two questions [when to turn water on and when to turn it off] should come from monitoring the soil.” Dr. Melvin D. Campbell
- 12. WHERE DO THE DATA COME FROM? Solar Radiation Wind Temp Humidity Rain ZL6 Data Logger - Solar charging - Cell enabled - Data directly to cloud Soil Moisture
- 14. STEPS FOR SCHEDULING IRRIGATION BY SOIL MOISTURE MONITORING • Select a monitoring site • Select a moisture monitoring method • Set the full and refill points • Select and use a record-keeping scheme
- 15. SITE SELECTION The “Field” average is not needed Since the “field” is irrigated as a unit, monitor only one representative site
- 16. CHARACTERISTICS OF A REPRESENTATIVE SITE • Away from the edge • Healthy, vigorous plants • No runoff/run-on, good water holding capacity soil • Representative exposure to irrigation and climatic conditions
- 17. ZL6 has GPS so georeferencing is automatic and shown on ZENTRA Cloud
- 18. MOISTURE MONITORING: WHAT TO MEASURE? Water potential–TEROS 21 Energy state of water in soil -Is the water available to the plant? -Will the water run out the bottom? Water content–TEROS 10, 11, 12 Amount of water in soil -When to irrigate next -How much water to add
- 19. WATER CONTENT VS. WATER POTENTIAL – 3 SOIL TEXTURES
- 20. MEASURE AT TWO OR MORE DEPTHS Shallow sensor monitors root- zone moisture Deeper sensors can show drainage loss More than two sensors needed for reliable water balance
- 21. FIRST APPROXIMATIONS OF FULL AND REFILL POINTS Water potential basis Full point is -10 to -30 kPa water potential Permanent wilt is -1500 kPa water potential Refill point is around -100 kPa Water content basis Full point is water content at -30 kPa Permanent wilt is water content at -1500 kPa Refill is water content at -100 kPa Is different for every soil
- 22. WATER CONTENT FULL AND REFILL POINTS FROM MOISTURE RELEASE DATA
- 24. KEEP A RECORD • Show time trends of soil moisture within and below the root zone • Show the full and refill points • ZENTRA Cloud does this for you
- 25. FOOD PROCESSING WASTE WATER DISPOSAL ON SANDY LOAM SOIL 0 2 4 6 8 10 12 14 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 6/22/2007 6/29/2007 7/6/2007 7/13/2007 7/20/2007 7/27/2007 Irrigation(mm) VolumetricWaterContent(m3m-3) 15 cm 30 cm 60 cm Applied Water mm
- 28. DOES GOOD IRRIGATION MANAGEMENT PAY? Yield vs. Water Potential Graph Site Days in stress Yield (Mg/ha) 9 42 31.47 12 53 32.77 10 44 37.44 11 0 39.67 6 0 40.08 7 16 40.33 30 32 34 36 38 40 42 0 10 20 30 40 50 60 Yield(Mg/ha) Days below -100 kPa
- 29. CONCLUSIONS • Good irrigation management pays, in the short run and in the long run • Soil moisture monitoring is the best starting point for good management • New water content and potential sensors, linked with sensor-to-cloud technology makes irrigation management effective and simple
- 30. FUTURE WEBINAR ADVANCED IRRIGATION MANAGEMENT: PLANT WATER RELATIONS AND ATMOSPHERIC DEMAND