352.T1

Model Agricultural Core Curriculum: SupplementUniversity of California, Davis

Irrigation Terminology

Soil Moisture Conditions

Saturation Field Capacity Wilting Point

Too Wet Ideal Too DryNo air space. Balance between No available

air - water - soil. water.

352.T2

Model Agricultural Core Curriculum: SupplementUniversity of California, Davis

Irrigation Terminology

Waterlogging

Normal root zone

Ground line

No root development Water-logged soil

352.T3

Model Agricultural Core Curriculum: SupplementUniversity of California, Davis

Irrigation Terminology

Water Holding Capacity (WHC)

Coarse Textured Soil Fine Textured Soil

Low WHC

The larger the soil particle size, the lower the water holding capacity.

High WHC

352.T4

Model Agricultural Core Curriculum: SupplementUniversity of California, Davis

Irrigation Terminology

Water Intake Rate

Coarse Soil Fine Soil

Generally, the larger the soil particle size, the faster the water intake rate.

High Water-Intake Rate Low Water-Intake Rate

352.T5

Model Agricultural Core Curriculum: SupplementUniversity of California, Davis

Irrigation Terminology

Field Capacity

• When all of the excess water has drained from the soil it is said to be at Field Capacity (FC).

352.T6

Model Agricultural Core Curriculum: SupplementUniversity of California, Davis

Irrigation Terminology

Wilting Point

• The point at which soil moisture is so low that plants can no longer pull water from it.

• Plants will die unless watered immediately.

352.T7

Model Agricultural Core Curriculum: SupplementUniversity of California, Davis

Irrigation Terminology

Permanent Wilting Point

• The point at which the plant has lost so much water that it will not revive even if watered immediately.

352.T8

Model Agricultural Core Curriculum: SupplementUniversity of California, Davis

Irrigation Terminology

Available Water (AW)

• The water which is available to the plants.

• AW is found by subtracting the wilting point measurement from the field capacity measurement.

AW = FC - WP