1. Understanding soil air/water dynamics

2. No-till soilTilled soil Porosity the soil’s respiratory and circulatory system (Young and Ritz, 2000) White zones are pores > 1mm

3. http://www.mtm.kuleuven.ac.be/Research/NDT/IDO_SHerman_final.ppt Soil pores come in many sizes and shapes

4. Intensive tillageLong term no-till AgriCanada plow pan well connected network of biopores

5. Effect of previous 20 years of rotations on SOM and corn growth on Beltsville silt loam in Maryland Continuous corn with tillage Continuous bluegrass sod

6. 25 yrs of CT corn 20 yrs of bluegrass, then 5 yrs CT corn

7. After adding water 25 yrs of conventi onal corn 20 yrs of bluegrass, then 5 yrs conventional corn After adding water

8. Least Limiting Water Range dry Soil water content, cm 3 /cm 3 *100 wet 2025303540455055 Root growth rate  LLWR for loose well-aggregated soil   LLWR for compacted soil  Not enough O 2 for root respiration Soil too hard for roots to penetrate From Weil, 2003 Ray Weil

9. June July August Soil Moisture (% of saturation) 100 75 50 25 8” 16” How does compaction affect a soil’s least limiting water range? Uncompacted soilCompacted soil LLWR

10. Compacting effects of wheel traffic Chapter 7 in Ross (1989) Cone resistance Bulk density Number of wheel passes

11. AgriCanada Without restricted traffic, most field surfaces receive traffic each year

12. (Watts and Dexter, 1997) Compaction Soils with more OM are weaker when dry and stronger when wet ! Tillage and traffic damages wet soils !!!

13. Why are soils more compactible at field capacity than at saturation? Soil will flow before water filled pores collapse

14. http://www.bettersoils.com.au/module6/6_3.htm < 1 MPa 1 - 3 MPa > 3 MPa 1 MPa = 145 psi Prenetrometer pressure Moisture strongly affects penetration resistance!! The same soil can be hard when dry and weak when wet.

15. Understanding bulk density Soil structure must be intact and soil must be oven dry

16. It is often said that bulk densities > 1.6 g / cm 3 are root restrictive… Is this true ??

18. Compactive force

19. So how does compaction impact soil water relationships ? Loss of drainage pores Gain in small pores

20. Plant available water 10-30 μm Drainage pores Unavailable water Adapted from Buol (2000) Most available Soil circulatory system ~0.2 μm less available Field Capacity Wilting point Saturation

21. Impact of texture on soil water Available water Brady and Weil, 2002 35 - 14 21% 21% of 12” ~ 2.5”

22. SOM increases plant available H 2 0 Adapted from Brady and Weil (2002)

23. Measuring infiltration rate

24. 12” 6” 50% porosity saturation Macropores Plant available H 2 O 50% plant available H 2 O 2.5” 1.25” 3.5” Total water at field capacity 50% solids 6” Visualizing water in a 1 foot layer of soil

25. 50% plant available H 2 O 1.25” How much water is need to bring the soil to field capacity ? What will happen if more than 1.25” of water infiltrates into this soil ? Water will percolate deeper than 1’

26. How fast does water move through soil ? Flow rate = Area*K sat *pressure head/length Brady and Weil, 2002 Darcy’s Law Hydraulic conductivity

27. Permeability = Hydraulic conductivity Flow rate ~ pore radius 4

28. Coarse textured layer Fine textured layer How does the presence of a coarse textured layer under a fine textured layer affect percolation ?

29. http://www.personal.psu.edu/asm4/water/drain.html Coarse textured layer Water will not enter the coarse textured layer until the upper layer is near saturation After water enters the coarse textured layer, it will percolate more quickly.

30. Does a thin layer of coarse material improve drainage ? NO ! Thin layer with coarser texture

31. Slit filled with coarse material Soil capped slit Systems for rapidly draining surface water should be open to the surface

32. Slit trenching equipment Outlets are needed !!

33. The current guide reflects recent developments in drainage science and technology. Most of these are related to new equipment and materials, widespread use of computers, and water quality considerations. It includes information not in the previous edition on pipeline crossings, water and sediment control basins, drain fields for septic systems, design of drainage water management systems, and design charts for smooth-walled pipes.

34. In Illinois, soil drainage is rated using a number (1 to 4) and letter (A or B) system. The number indicates the degree of soil permeability. The letter indicates the natural drainage. 1 Rapidly permeable More than 6 inches per hour Moderately rapidly permeable 2 to 6 inches per hour 2 Moderately permeable 0.6 to 2 inches per hour 3 Moderately slowly permeable 0.2 to 0.6 inch per hour 4 Slowly permeable 0.06 to 0.2 inch per hour Very slowly permeable less than 0.06 inch per hour IL Permeability classes

35. A Poorly drained The water table is at or near the surface during the wetter seasons of the year Very poorly drained The water table remains near, at, or above the surface much of the time B Somewhat poorly drained The water table is near the surface only during the very wettest periods

37. Bioreactor vs. standard tile outlet

41. One calorie is the amount of thermal energy required to raise the temperature of one gram of water by one Celsius degree. 3000 calories of thermal energy enters each cup. The temperature of the water on the left rises by 30 Celsius degrees. By how much does the temperature of the water in the cup on the right rise ??

42. Why does soil heat up faster than water ? The heat capacity of water is ~ 5 times higher than the heat capacity dry soil. As a result, moist soils heat up and cool down more slowly than dry soils.

43. Water has a high thermal conductivity Air has a low thermal conductivity What can be done to maximize geothermal heat transfer ? compacted vs. loose ? moist vs. dry ?