Estimating Soil Moisture by Feel and Appearance
Irrigation Water Management (IWM) is applying water
according to crop needs in an amount that can be stored in the plant root zone
of the soil.
The "feel and appearance method" is one of several irrigation scheduling
methods used in IWM. It
is a way of monitoring soil moisture to determine when to irrigate and how much
water to apply. Applying too much water causes excessive runoff and/or deep
percolation. As a result, valuable water is lost along with nutrients and
chemicals, which may leach into the ground water.
The feel and appearance of soil vary with texture and moisture content. Soil
moisture conditions can be estimated, with experience, to an accuracy of about 5
percent. Soil moisture is typically sampled in one-foot increments to the root
depth of the crop at three or more sites per field. It is best to vary the
number of sample sites and depths according to crop, field size, soil texture,
and soil stratification. For each sample the "feel and appearance method"
- Obtaining a soil sample at the selected depth using a probe, auger, or
- Squeezing the soil sample firmly in your hand several times to form an
irregularly shaped "ball";
- Squeezing the soil sample out of your hand between thumb and forefinger to
form a ribbon;
- Observing soil texture, ability to ribbon, firmness and surface roughness
of ball, water glistening, loose soil particles, soil/water staining on
fingers, and soil color. [Note: A very weak ball will disintegrate with one
bounce of the hand. A weak ball disintegrates with two to three bounces];
- Comparing observations with photographs and/or charts to estimate percent
water available and the inches depleted below field capacity.
Appearance of different types of soil at various moisture conditions:
||Available Water Capacity (AWC) for Zone
||Soil Moisture Depletion (SMD)
||0 to 12 inches
||12 to 24 inches
||24 to 36 inches
||36 to 48 inches
AWC total for all sample
depths = 6.8 inches.
SMD total for all
sample depths = 3.1 inches.
A 3.1 inch net irrigation will refill the root zone.
If you encounter any problems with the file provided on this
page, please contact Technical Resources at 406-587-6822.
Estimating Soil Moisture by Feel and Appearance is also
available for downloading. This document requires
Soil Moisture by Feel and Appearance (PDF; 678KB)
< Back to Agronomy