In plain English, the presentation explains what can and cannot be done to mitigate the effects of clay content in soil. It includes some basic irrigation terms and their definitions, within the context of soil texture.

1. Plain Talk About Clay Soils Serenity, courage, wisdom Linda J. Brewer Extension Horticulture Oregon State University

2. God grant me the serenity to accept the things I cannot change; 9/29/05

3. courage to change the things I can;

4. and wisdom to know the difference.

6. Fact #1: Soil includes minerals, organic matter, air and water. Minerals 45% Solid stuff Fluid stuff Air 20-30% Water 20-30% Organic matter 5%

7. Fact #2: Soil texture is the percentage of sand, silt and clay. Soil texture cannot be changed. 

9. Fact #3: Soil minerals exist as sand, silt and clay particles. Sand particles are big. Clay particles are small.

10. Sand: big particles, big pores. Clay: little particles, tiny pores.

12. Used with permission: Bradshaw, M and R. Weaver. 1995. Foundations of Physical Geography. W.C. Brown Communications, Inc. Dubuque, IA. Subduction zone

13. Fact #4: Same volume, different surface area . Surface area = 2X2X6X8 = 192 sf Do the math and prove it to yourself! 4’ 4’ Surface area = 4X4X6 = 96 sf

14. Small particles, enormous surface area. Big particles, small surface area.

17. Gravity Coarse texture <5 minutes

18. Fine texture 20 minutes Capillarity and gravity.

19. Capillarity and gravity. 60% Clay >90 minutes

21. Fine texture over coarse texture 7 minutes 2 minutes

22. Coarse texture over fine texture

23. Fact #6: A plant taking up water is playing tug of war with the soil. Clayey soils hold water tightly. Sandy soils have limited storage capacity. Image used with permission from the BBC’s Schools Website Evaporation

24. Transpiration drives water flow toward roots. Roots explore for water. root growth Plant root diffusion

25. Saturation = Soil Soup

26. Plant Available Water capillarity gravity evaporation

27. Fact #7: Unavailable Water As soil dries out, it holds on to water more tightly. capillarity not connected

28. Fact #8: Soil’s water storage depends on texture. stored water more less clay sandy loam silt loam sand loam clay loam soup water available to plants unavailable water field capacity permanent wilting point

29. Fact #9: Like diamonds, soil texture is forever. 

38. Linda J. Brewer Extension Horticulture Extension Small Farms [email_address] 541-737-1408