Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Soil Moisture 201: Moisture Release Curves

72 views

Published on

Are you interested in the water stored in the soil? Do you care more about water available for primary productivity? Are you studying water and solute movement in soils? Do you aim to optimize water use of crops? Are you modeling soil hydrology?

After this webinar you will:
• You will have a better understanding of the importance of water potential
• How you can utilize soil moisture release curves for irrigation planning
• What additional information lives within the soil moisture release curve
• What factors affect field capacity


Presented by Leo Rivera, METER Environment.

Published in: Science
  • Be the first to comment

Soil Moisture 201: Moisture Release Curves

  1. 1. SOIL MOISTURE 201 MOISTURE RELEASE CURVES-REVEALED Leo Rivera METER Group, Inc. USA
  2. 2. INTRODUCTION ABOUT ME Background in Soil Physics & Pedology 12 years of experience measuring and interpreting soil hydraulic properties and soil moisture release curves
  3. 3. INTRODUCTION WHAT DOES SOIL MOISTURE EVEN MEAN? Are you interested in the water stored in the soil? Do you care more about water available for primary productivity? Are you studying water and solute movement in soils? Do you aim to optimize water use of crops? Are you modeling soil hydrology? 4
  4. 4. GOALS • You will have a better understanding of the importance of water potential • How you can utilize soil moisture release curves for irrigation planning • What additional information lives within the soil moisture release curve • What factors affect field capacity
  5. 5. EXTENSIVE VS. INTENSIVE PROPERTIES Two variables necessary to describe state of matter or energy in environment Extensive variable – describes the extent or amount of matter or energy Intensive variable – describes the intensity or quality of matter or energy Extensive Intensive Volume Density Water Content Water Potential Heat Content Temperature
  6. 6. EXTENSIVE VS. INTENSIVE Heat Content Temperature Energy flow?
  7. 7. WHAT IS WATER POTENTIAL?
  8. 8. WATER POTENTIAL DEFINITION Energy required, per quantity of water, to transport, an infinitesimal quantity of water from the sample to a reference pool of pure, free water
  9. 9. TOTAL WATER POTENTIAL SUM OF COMPONENTS yT = ym + yg + yo + yp yT – Total water potential ym – matric potential - adsorption to surfaces yg – gravitational potential - position yo – osmotic potential - solutes yp – pressure potential - hydrostatic or pneumatic
  10. 10. SOIL FINGERPRINT SOIL WATER RETENTION CURVES EXTENSIVE INTENSIVE
  11. 11. MAKING DECISIONS IRRIGATION How can we use Soil Moisture Release Curves to make irrigation decisions? We need to understand both water potential and water content VWC – How much irrigation to apply Water potential – availability of water to crops
  12. 12. 6/11/19 IRRIGATION REQUIREMENTS SILT LOAM -100 kPa = 0.24 m3 m-3 -33 kPa = 0.32 m3 m-3 Irrigation zone depth = 15 cm (5.9 in) Required irrigation = (0.32-0.24) x 15 = 1.2 cm (0.47 in)
  13. 13. 6/11/19 IRRIGATION REQUIREMENTS FINE SANDY LOAM -100 kPa = 0.10 m3 m-3 -33 kPa = 0.16 m3 m-3 Irrigation zone depth = 15 cm (5.9 in) Required irrigation = (0.16-0.10) x 15 = 0.9 cm (0.35 in)
  14. 14. WHAT FACTORS LIMIT PLANT WATER AVAILABILITY? Field Capacity Permanent Wilting Point What other information is in a soil moisture release curve? Uniformly-Graded Well-Graded Gap-Graded
  15. 15. WHAT FACTORS LIMIT PLANT WATER AVAILABILITY? 0 10 20 30 40 50 60 70 80 0.01 0.1 1 10 100 1000 10000 100000 1000000 WATERCONTENT,% WATER POTENTIAL, -KPA Uniformly-Graded Well-Graded Gap-Graded
  16. 16. FIELD CAPACITY DEFINITION Field water capacity is “the content of water on a mass or volume basis, remaining in a soil 2 or 3 days after having been wetted with water and after free drainage is negligible.” Glossary of Soil Science Terms. Soil Science Society of America, 1997 About -33 kPa 17
  17. 17. TRUE FIELD CAPACITY WHAT DO WE MEASURE IN THE FIELD What does field capacity look like in the real world. Where does the water potential stabilize Does this represent my soil?
  18. 18. TRUE FIELD CAPACITY? CAN VARY SITE TO SITE Typical soil Connection with water table Capillary Barrier Effect Silt Loam Water Table Silt Loam Water Table Sand
  19. 19. TOOLS FOR MEASURING WATER POTENTIAL
  20. 20. HOW FAR WE HAVE COME TOOLS FOR MEASURING WATER POTENTIAL HYPROP WP4C
  21. 21. SOIL MOISTURE RELEASE CURVE WHAT ELSE CAN IT TELL ME? • Shrink swell capacity • Cation exchange capacity • Soil specific surface area
  22. 22. HYDRAULIC CONDUCTIVITY CAN IT AFFECT PLANT WATER AVAILABILITY? Limits water redistribution Water potential near root-soil interface can be much lower. 1.00E-09 1.00E-08 1.00E-07 1.00E-06 1.00E-05 1.00E-04 1.00E-03 1 10 100 1000 K,cm/s y, kPa FSL LFS SiL Potting Soil McCorkle
  23. 23. RECAP WHAT’S NEXT? Soil Moisture 101 – basics of water content and water potential Soil Moisture 201 – A deeper look at water potential Focused on states What are we missing? What is the end goal? Flux data & rate data.
  24. 24. ECOSYSTEM FLUXES THE BIG PICTURE
  25. 25. SOIL MOISTURE 201 QUESTIONS?

×