IRRIGATION WATER CONVEYANCE AND REQUIREMENTS

WHAT HAPPENS AFTER DIVERSION?

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THE REAL WORLD VIEW

DITCH AND CANAL LINERS

PIPE FLOW

OR PUMPS

BY GRAVITY

CROP SEED PRODUCTION

Apply water to meet the crop needs

HAY PRODUCTION

EFFECTIVE ROOT ZONE

ROOT DEVELOPMENT AND SOIL LIMITATIONS

MODIFIED ROOT DEVELOPMENT

50%

33%

17%

0

EFFECTIVE ROOT ZONE

HIGH WATER TABLE

LIMITS ROOT DEVELOPMENT

ONE SIZE DOES NOT FIT ALL!!!

WE OFTEN USE THE METHOD THAT SEEMS MOST FAMILIAR EVEN WHEN THERE ARE BETTER WAYS TO DO IT.

APPLICATION METHODS

MANAGEMENT IS THE

ESSENTIAL REQUIREMENT

WATER MEASUREMENT

TOO MUCH WATER MAY CAUSE

Infiltrating furrow streamTransport

Detachment

Deposition

Source

Inflow

Runoff and sediment loss

Tail Ditch

NWISRLNWISRLKimberly, IDKimberly, ID

Poor Design, Soil & Landscape Variability,Poor Design, Soil & Landscape Variability,Application Rate, etc. Can Create ProblemsApplication Rate, etc. Can Create Problems

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TOO MUCH WATER IN ANY SYSTEM

MAY LEAD TO OTHER PROBLEMS

OVER IRRIGATION AND EROSION

Adequate soil moisture monitoring

SEASONAL USE AT SOIL DEPTHS2003

-100

-80

-60

-40

-20

0

cent

ibar

s

Sensor 1 - 6 inches Sensor 2 - 18 inches

April May

Field Capacity

June July August September OctoberMarch

GRASS HAY - POTOMAC – MISSOULA COUNTY

Sprinkler Efficiency Overview

• NRCS NATIONAL IRRIGATION GUIDE (Table 6-4)

– Periodic move lateral 60-75%– Traveling sprinkler (big guns) 55-65%– Center pivot - standard 75-85%– Linear (lateral) move 80-87%– LEPA Center pivot or linear 90-95

GROSS Vs NET REQUIREMENTSThe Gross application is that amount applied

over the whole area to get the Net amount in to the soil where it can be used by the plant.

• To obtain a 1inch NET application with a 50% efficient system one must apply 2 inches.

• A 75% efficient system would need to apply a 11/3 inch Gross to get the same 1 inch NET.

EFFECT OF LIGHT APPLICATIONS 2003

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

cent

ibar

s

Sensor 4 - 6 inches Sensor 5 - 18 inches Sensor 6 - 30 inches

April May June July August September October

Field Capacity

DATA BREAK

SHALLOW APPLICATIONS

LOWER SOILS NOT IRRIGATED

14.8 in.

12.7 in.

SOMETIMES WE MAKE THINGS HARDER THEN NECESSARY

SUMMARY• Conveyance losses (control limits, evaporation,

leakage, etc.) reduce the amount of H2O taken from a source that is available for application to the field.

• Application losses come in many forms: – Weather – Wind, heat, humidity, evaporation, etc.– Soils – Intake limits, water holding capacity effects– System – Uniformity, leaks, maintenance effects– Management – Flow controls, Time limitations, & lack of

Measurements of Flow rate and Soil Moisture• The remaining water getting to the root zone is what

is available to the plant for growth.

QUESTIONS??