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SOIL INTAKE
CHARACTERISTICS GUIDE |
Irrigation to be Applied |
Intake Family
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0.1 |
0.3 |
0.5 |
0.75 |
1.0 |
1.25 |
1.5 |
1.75 |
2.0 |
(Inches) |
Time (Hours) |
2" |
10.5 |
3.5 |
2 |
1.5 |
1 |
0.8 |
0.7 |
0.6 |
0.5 |
3" |
22.3 |
6.8 |
3.8 |
2.8 |
1.8 |
1.5 |
1.3 |
1.1 |
0.9 |
4" |
34 |
10 |
5.5 |
4.1 |
2.6 |
2.2 |
1.8 |
1.6 |
1.3 |
5" |
49 |
14 |
7.6 |
5.6 |
3.6 |
3 |
2.4 |
2.2 |
1.8 |
6" |
64 |
18 |
9.7 |
7.1 |
4.6 |
3.8 |
3 |
2.7 |
2.3 |
| Irrigation to be Applied: approximately 2" - 6"
of irrigation water are applied/acre/irrigation. These quantities are applied ONLY
when the irrigation water (river and/or well) is conveyed through canals, laterals, pipes,
and ditches as the method for irrigating. The irrigation water is discharged unto the
farmland through various types of outlets (e.g., 10" - 12" diameter pipe, hi-flo
irrigation structures, alfalfa valves). Used in furrow/flood basin. |
| Intake Family (i.e., for border and basin irrigation): the intake
family number of a soil relates the time required to infiltrate a given quantity of
water in a specific soil type. Since the intake rate of the soil decreases as more water
is applied, the family designations (e.g., 0.1, 0.5, 1.0, etc.) reflect the final intake
rate of the soil. |
| Time (Hours): This is the total hours required (i.e.,
Opportunity Time) for the given IRRIGATION application amount to infiltrate into the
soil for a specific Intake Family. The times shown in the table do not
reflect the total time of irrigation set. |
Key Considerations: The
intake rate of the soil under irrigation is affected by many factors such as:
¶ Texture: The texture, or the size of the soil
particles, greatly affects the rate at which water enters the soil. Slower intakes are
usually associated with the soils that have a large amount of clay or fine particles and
faster intake rates are usually are found in the more sandier soils.
¶ Compaction: Tillage operations may cause
compaction and the formation of plowpans below cultivation depths. A plowpan impedes water
movement and thus slows down the intake rate of the soil.
¶ Organic Matter: Intake rates can be maintained
and even increased by using a cropping system that provides high amounts of crop residues
in the upper few inches of the soil.
¶ Salts in the Soil: Salts contained in the
irrigation water may accumulate in irrigated soils and affect the intake rate of the soil.
High concentrations of sodium salts may affect the soil structure, disperse the fine clay
particles, and reduce the intake rate of water. Under some conditions, high accumulations
of calcium and magnesium salts may have a positive affect on the intake properties of the
soil.
¶ Sediments in the Irrigation Water: Fine silt
and clay particles carried in suspension affect the quality of the irrigation water.
Whether this is detrimental or beneficial depends on the amount of silt transported, the
length of time the silty flow continues, and the texture of the soil to which the water is
applied. |
Technical Questions about HIT may possibly be
quickly answered by contacting:
Rudy Garcia
Natural Resources Conservation Service
Soil Conservationist & Water Quality Specialist
e-mail: rgarcia@nm.nrcs.usda.gov
or call: 1-505-522-8775, extension 116
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