1. Estimating Soil Moisture by Appearance and Feel
By N. Klocke and P. Fishbach

2. Evaluate soil moisture
Important management tools
How much to irrigate
When to irrigate
“appearance and feel” method
Where moisture is located in the profile
Depth of water penetration from irrigation or rainfall
ID problem areas soil compacted layers that restrict water penetration

3. Soil Texture Relative amount of sand, silt and clay
Indicates amount of water soil will hold
Available water capacity is max water the soil holds that plants can use

4. Available water capacity for soils
Soil texture available water
inches/foot
Fine sand or loamy sand 1.0 to 1.1
Sandy loam 1.4
Loam or silt loam 2.0 to 2.5
Silty clay or clay loam 1.8

5. Knowing water potential
Different soil types respond differently to method described
Key is texture
County soil survey
Cooperative Extension Office or Natural Resource Conservation Service office

6. Sampling and Evaluation Procedures
Extract sample. Probe, auger, spade
One foot intervals
Surface to bottom of active root zone
Most crop – 3 feet
Start early in spring – 1 to 2 days after a heavy rain
Soil near field capacity
End of growing season
Soil is dry
Use photo descriptions

7. Guides for estimating soil moisture
Soil probe extract the sample
Scrape clean before inserting probe
Pull sample back to surface
Inspect soils, remove all soil
Clean probe after each use

8. Procedure using description
Determine texture
Squeeze firmly
Observe condition of soil ball
Attempt to form a ribbon
Observe what happens
Compare your observations with photos and descriptions in guides

9. Use photo descriptions
From
Sandy clay, loam and silt loam soils
Available water capacity = 1.5 to 2.1 inches per foot
% available : current available soil moisture as % of available water capacity
Inches per foot depleted: inches of water currently needed to refill a foot of soil to field capacity

10. 0 to 25% available 2.1 to 1.1 inches per foot depleted
Dry,
soil aggregations breaks away easily,
no staining on fingers,
clods crumble with pressures

11. 25% to 50% available 1.6 to 0.8 inches per foot depleted
Slightly moist
Forms a weak ball with rough surfaces
No water staining on fingers
Few aggregated soil grains break away

12. 50% to 75% available 1.1 to 0.4 inches per foot depleted
Moist
Forms a ball
Very light staining on fingers
Darkened color
Pliable
Forms a weak ribbon between thumb and forefinger

13. 75% to 100% available 0.5 to 0.0 inches per foot depleted
Wet
Forms a ball with well defined finger marks
Light to heavy soil/Water coating on fingers
Ribbons between thumb and forefinger

14. 100% available 0.0 inches per foot depleted (field capacity)
Wet
Forms a soft ball
Free water appears briefly on soils surface after squeezing or shaking
Medium to heavy soil/water coating on fingers

15. Use photo descriptions
From
Clay, clay, loam and silt clay loam soils
Available water capacity = 1.6 to 2.4 inches per foot
% available : current available soil moisture as % of available water capacity
Inches per foot depleted: inches of water currently needed to refill a foot of soil to field capacity

16. 0 to 25% available 2.4 to 1.2 inches per foot depleted
Dry,
soil aggregations separate easily,
Clods are hard to crumble with applied pressure

17. 25% to 50% available 1.8 to 0.8 inches per foot depleted
Slightly moist
Forms a weak ball
Very few soil aggregations break away
No water stains
Clods flatten with applied pressure

18. 50% to 75% available 1.2 to 0.4 inches per foot depleted
Moist
Forms a smooth ball with defined finger marks
Light soil/water staining on fingers
ribbon between thumb and forefinger

19. 75% to 100% available 0.6 to 0.0 inches per foot depleted
Wet
Forms a ball
Uneven medium to heavy soil/water coating on fingers
Ribbons easily between thumb and forefinger

20. 100% available 0.0 inches per foot depleted (field capacity)
Wet
Forms a soft ball
Free water appears on soil surface after squeezing or shaking
Thick soil/water coating on fingers
Slick and sticky

21. Calculating soil moisture status
After estimating soil moisture, water can be calculated using table values
Example: silt loam
Available water at FC = 2.4 inches / foot
Current status = 50% available soil moisture remaining
Amount of soil in sample = 1 foot
Available moisture remaining = 50* 2.4 in/ ft * 1 ft = 1.2 inches

22. Other sites How to estimate soil moisture by feel
Why know available soil water?
Management decisions
Favorable moisture, plant population, nutrients applied
Large acreages
Several day to cover area
Most crops start irrigation when 50% available moisture in root zone is depleted

23. Chart below from http://sanangelo. tamu. edu/agronomy/sorghum/moisfeel
Degree Percent Appearance of soils
of soil useful soil
moisture moisture __________________
Dry powdery, hard, baked,
slightly crusted cracked__
Fair % forms a ball, forms a ball,
somewhat will ribbon
plastic_________________
Ideal at FC squeezing, no free water
appears, wet outline of ball left
on hand

24. Knowing the texture and topsoil depth
Estimate available water
Soil texture is silt or clay loam
1.5 to 2 inches of available water per foot
Soil texture is clay
2-2.5 inches of available water per foot of topsoil