1993 report to the USDI Bureau of Reclamation, Grand Valley demonstration project

tI 1 i L I

W

y

₁₁

7 V 1 v

f

y

1

COLORADO

STATE

UNIVERSITY

COOPERATIVE

EXTENSION

1993

Report

To The

USDI

Bureau

of

Reclamation

GRAND VALLEY

DEMONSTRATION

PROJECT

Richard C

Bartholomay

Ertension

_{Agellt Irrigation}

Daniel F

_Champion

GO 14 oJ f

i

Report

to the United States

Department

of the Interior

Bureau of Reclamation c

Coooerative

Aareement for Surae Irriaation Research

and _{Develooment Proaram Grand Vallev Unit}

SUMMARY

As a resuit of a _{grant from} the USDI Bureau of Reclamation 0 FC 40 09270 l to Colorado State

_{University Cooperative}

_{Extension surge}

_irrigation

_{valves and}

controllers were

_supplied

to _{128 farm sites within the Grand}

Valley

of Colorado

The purpose of these installations is to test and _{demonstrate surge}

technology

to

area farmers The

_equipment

also enables

_irrigators

to

_improve

their

_irrigation

efficiency

and to _{reduce the}

_deep

_percolation

_{and its resultant salt}

loading

of the

Colorado River The valves were _installed

_by

_{the cooperators on fields of}

corn

alfaifa small

_grain

beans _pasture and orchard _crops

Cooperative

Extension personnel studied 149

_irrigation

events

_throughout

the

1993

_irrigation

season _{Of these 140}

_provided

_{usable data and 41}

events

_provided

comparisons

between conventional and _surge Results of the

_irrigation

evaluations

with _surge as well as with

_{conventionally irrigated}

_{fields indicated that the}

surge

irrigations

were instrumental in

_reducing

_deep

_percolation

_{of excess}

irrigation

water

The 41 direct

_comparison

_{evaluations from the 1993}

irrigation

season indicated

that

_deep

_percolation

was reduced

_by

21 acre inches which translates into a salt

load reduction of 28 tons

Reducing

deep

percolation

losses

_by

560 acre inches

_during

the 4

_irrigation

seasons indicates the

_potential

_savings

_{due to}

_equipment

improvements

The 560 acre inches of

_{deep percolation}

_{reduction left} over 1 000 tons of salt in

_place

Additional benefits may be achieved with

_improved

water _management

Projections

based on _{the average} salt load reduction over the four _year

_period

indicate a total salt

_saving

of 1 617 tons

_during

the 1993 season This salt

reduction of 1 617 tons should continue

_during

the life of the

_equipment

_assuming

that current water _management

_practices

_continue

C j l t

Report

to the _{USDI Bureau of}

Reclamation

from

_Colorado

_State

University

Cooperative

Extension

BACKGROUND

Surge

irrigation

has been

_recognized

_{for a number}

of years for its

_ability

_{to enhance}

irrigation

water

_advance

_{across a field}

The

_principle

_involves

_a

valve _operated

_by

a _{motorized controller which}

Switches the

_irrigation

_{water from}

one side of _{the field} to _{the other at prescribed times}

The first

_{application advances}

down a short

portion

of one _{side of the set before}

the water is _{switched over to}

the alternate

side to

_advance

_{the water the}

same

_distance

_{It is}

powered

_by

a solar _collector

attached to a

_battery

_{and is}

relatively

maintenance

free The _{number of}

_cycles

_of

alternating

the water from one side to the other is

_dependent

upon the soil _type

length

of

_irrigation

run and the amount of water _{available for the}

irrigation

After the initial

_alternating

_{times called}

out _{times the}

cycles

are

_decreased

_in

length

of time to

_soaking

_{or cutback times}

At this

_point

the _{field should be}

wetted

through

to the _{end and excess water}

runoff _{tailwater should be}

minimized

Several theories

exist as to

_why

_surge

_irrigation

works The most

_accepted

_version

is that the water _{may continue to penetrate}

the soil even _{after the}

irrigation

water

is removed _{from it this may result in}

some soil

_sealing

_by

breaking

of some

capillary

flow and _{less penetration when the}

next _{surge of water}

is

_applied

Thus the water _{may travel further}

down the furrow with less water

_applied

_{than if} the water had been

_applied

continuously

As a _result

vastly improved

_irrigation

efficiencies

_{have been realized}

by

many

irrigators

and the

_conclusions

_{have been}

iL

published

in _several

_journals

t r I _{i l} J y

r

1 v L The Grand

_Valley

is _{situated in west central}

Colorado

In _any

_given

year about

60 000 acres are

_{irrigated by}

gravity

flow water

_delivered

through

mostly

unlined canals from the

_Colorado

_{River The entire}

area is _underlain

_by

_{a saline}

marine

formation

known as

_Mancos

_{shale Since the}

irrigation

water is

_plentiful

_and

inexpensive

_considerable

_over

irrigation

occurs _{This overil}

rigation coupled

with

leakage

from the unlined canals

_contributes

about

600

000

tons of salt

_annually

from the

shale

_through

_{return flow to the}

Colorado

River

_drainage

_Principal

crops

are corn _{for both}

_grain

_and

silage

alfalfa

_hay

small

_grains

_{and orchard fruits}

Smaller acreages

of onions

_dry

beans and

_soybeans

_are

scattered

_throughout

_the

valley

Production

on a _per acre _{basis is}

good

THE GRAND

VALLEY

THE SURGE

PROJECT

One

_hundred

twenty eight

cooperators were invited to

_participate

_in

the USBR

sponsored _surge

_project

_over

the four year periOd from ₁₉₉₀

o

I

7

cooperators were

_given

either an in line _surge valve a

_{gated pipe}

_T

_shaped

surge valve or a

_ported

_{ditch surge gate}

_together

_{with an}

appropriate

controller One

unit was made available for each _{farmer selected After a short}

workshop

on the

use of the _{surge valves the cooperators installed}

them in their

_irrigation

_systems and

_began

to use them for their first

_irrigations

The

_Cooperative

_{Extension team}

was able to

_study

149 _{conventional and}

surge

_{irrigations throughout}

the 1993

irrigation

season Both _{inflow and outflow of a}

_single

_furrow

were measured with

v notch _{furrow flumes and automated data}

gathering

devices A furrow that had

no wheel traffic upon it was _{selected for the evaluation}

This presented conditions

conducive to the

_greatest

amount of

_deep

_percolation

_{and least runoff of the}

applied

water a worst case _scenario

_Forty

_{one of the}

irrigations

produced

useable data _{The remainder} were _{rendered unusable due to furrow washouts}

and

crossovers _{and occasional malfunctions of the data}

gathering

equipment

Some of

the flumes became silted

_making

the data

_questionable

Total acres included 32 acres

_{conventionally irrigated}

_{and 28}

acres

_irrigated

_by

surge methods

during

the 1993

_irrigation

season All fields are not listed on the

attached tables due to _{data collection}

_problems

The SCS

_monitoring

team _{monitored two of the fields and}

provided

total inflow

and outflow _{water measurements from the fields}

Evapotranspiration

values for the

crops and software for

_evaluating

data were also

_{provided by}

the

_monitoring

team

EVALUATION

Irrigation

events were recorded on _{149 occasions}

_throughout

_{the 1993}

crop year with 140 events

_yielding

_{useable information The 2}

primary

causes _{of unusable}

data include water

_breaking

out of the furrows and the v _{notch flumes}

silting

up In _addition birds

_pulled

the

_string

_{from the flumes and small animals skunks}

and

raccoons disturbed the floats on occasion The two fields monitored

_by

SCS

provided

the most _{reliable data and}

_projections

_{will be made}

from this information

These fields are identified as _{M51 and M55 on the data sheet in}

the farm number column included with _{this report The other farm numbers are those}

where

individual furrow flows were measured See attached data sheets Note that some farms have

_negative

_{numbers in the}

_deep

percolation

column This indicates deficit

_irrigation

the water used

_by

the _crop was not

_{replaced totally by}

the

_irrigation

water and it

increases

the

_efficiency

to an _{unrealistic number Some} fields are _{believed to be sub}

_irrigated

_{with water from}

a

_higher

_{elevation The}

cause of the deficit

_irrigations

on the other fields is unknown

_Perhaps

_{the method}

of

_calculating

_{evapotranspiration}

may need to be refined and some data collection error _{may have occurred A crop}

_planted

_{earlier or later}

than _{the reference crop}

used for

_{evapotranspiration}

_{calculations will use water}

differently

than the

reference _crop

I to

J 4

Daily

evapotranspiration

rates

_provided

_by

_the

monitoring

section of the Soil

Conservation Service were used to _{determine soil}

moisture deficits between most

irrigations

The initial soil _{moisture deficit}

_prior

_to

irrigation

was _determined

_by

_the

hand feel method which was

_{substantiated}

_by

_a

gravimetric

evaluation of selected

samples

A

_comparison

_{of fields}

_identified

_{as M11}

M15 M43 M51 and _{M55 shows} a

difference in water use between the same _{crops in}

_different

years and a _difference

in crop use on the same farm _M43 Field

_comparisons

ACRE INCH _{ACRE INCH}

ACRE INCH

FIELD _{APPLIED a}

RUN OFF a _{DEEP PERC a}

NUMBER CONV _{SURGE CONV}

SURGE CONV SURGE

Mll 90 34 6 29 1 4 4 8 8 10 9 2 0 Mll 91 _{51 8 44 3} 3 7 _{11 4 15 9} 5 0 M15 90 76 9 49 3 32 5 16 9 20 7 10 7 M15 91 _{69 5 50 2} 24 1 14 8 23 1 14 5 M15 92 57 4 45 6 20 7 6 0 26 5 19 5 M43 90 65 8 50 8 16 2 17 5 31 2 13 7 M43 91 85 2 _{71 8 36 0} 24 7 23 7 22 3 M43 92 _{61 5 67 0} 18 0 14 2 14 2 26 6 M51 91 32 5 22 2 16 3 9 8 4 1 2 1 M51 92 38 1 21 9 ₁₅ 4 8 0 5 7 0 M51 93 24 5 19 1 8 2 7 4 1 1 0 M55 93 55 5 42 2 12 2 8 _{9 0 1 0} DATA

_ANALYSIS

Note the increased water use on farm M 11 between 1990 and 1991 This is a

well

_managed

_{orchard but water}

management can be

_{improved by}

_adjusting

_the

timing

of the cut back

_cycles

to reduce runoff Also _reduced set times combined

with proper cutback

_cycle

_timing

_{should reduce}

_deep

percolation

This field was

converted to _surge

_irrigation

_{for the 1992 season}

Farm M_{15 reduced the total amount of water used}

during

the 1991 season when

compared

to

1990

but set times were _{about the} same so

_deep

_percolation

_was increased

_during

1991

_Seventeen

_{of the 19 5 inches of}

deep

percolation

occurred

during

the initial

_irrigation

_{of the} corn

_during

_{crop year 1993} Increased water use on _{farm M43 reflect the}

change

from corn to alfalfa

_During

the _year of alfalfa

_{establishment}

_{1991 a}

larger

amount of water is used to assure

seed

_germination

_and

seedling development

Examination

of set time and furrow

flow data not _{included here indicate extended set}

1 if l

4 sixth

irrigations

and reduced furrow flow rates

_during

_{the second}

_irrigation

r

c _Data

obtained _{from field} M51 indicates _{the operator understands}

_irrigation

water

management as it

_pertains

to this field

Field M55 results show

_improved

water _{management and reduced}

deep

percolation

with the surge system

Comparisons

between fields that were full _{field monitored and fields that}

were

evaluated

_by

_single

furrow measurements are _{desirable but a limited number}

of

fields have total

_irrigation

events _{available for}

_comparison

Fields that lend

themselves to full field evaluations are difficult to find since few have isolated inflows and _{outflows for} accurate flow _measurements

SALT LOAD REDUCTION

Salt load reduction estimates _{made from the 5 fields that were}

fully

monitored

_by

the SCS

_monitoring

team

_during

_{the past four}

_irrigation

seasons are _{shown below}

Salt load reduction from selected fields

A B e 0 E F G H

Acre Inch reduction

Surge Salt from

_Surge

_Tons

Farm Acres _Tons a i 1990 1991 1992 1993 Total B x Clx Gl M11 MIS M43 MSl MS5 j v

1

1

L vilv

The 197 4 tons of salt saved divided

_by

the 43 5 acres

_indicates

an

_average

_salt v I

reduction of 4 5 tons _per acre over _{the four year trial from these}

selected fields

f _A J 7 5 16 6 4 8 9 6 5 0 0 280 0 263 0 341 0 263 0 28 8 9 10 17 5 10 9 8 6 1 4 2 0 19 8 25 6 6 5 8 8 8 0 Total 41 6 111 8 10 6 22 2 11 2 197 4 7 0 12 4 5 7 1 1 8 0

The cost of the _surge

_equipment

_purchased

under this agreement used on these five farms was 6 557 00 This

_equipment

is

_assigned

a 15 _{year life under the}

USDA

_portion

of the

Colorado

River

_Salinity

_Control

_Program

1

This

_equipment

cost of 6 557 00 _{amortized at 8 for the}

15 year life of the

surge units divided

_by

4 5 tons _per acre times 43 5 acres

_equals

_{3 91 per ton} of

salt

I

The tons of salt _per acre inch of

_deep

_{percolation shown in}

column C is less than

the

_{weighted valley}

_wide

average of 0 337 _{tons per acre inch shown}

in Table 1 5 c rl J V v l l

rci

0

L

oJ

EFFECTS OF ONFARM WATER MANAGEMENT Note that these factors are

used on the data sheets as salt tons acre inch on the data sheets for 1990 1991

1992 and 1993 These numbers have been

_generated

_by

USSR and USDA for the

different areas of the Grand

_Valley

based on measured salt contributions c

The total salt contribution from each field where data was obtained has been calculated

_using

the number of acres _{under surge the} acre inch reduction of

_deep

percolation

due to the use _{of surge}

_irrigation

and the tons of salt

_produced

per

acre inch of

_{deep percolation}

These numbers and the total are shown in the

_right

column of the data sheets

Additional incalculable

_salinity

benefits can be

_expected

to have occurred in that

not all

_irrigation

events on all farms were evaluated _{each year}

DEEP PERCOLATION REDUCTION

The amount of

_{deep percolation}

in acre inches

_by

conventional and _surge

_irrigation

divided

_by

the acres in each for all _years indicates a

_{deep percolation savings}

as a

result of surge

irrigation

as shown below

comparison

of _deep

_percolation

_by

_system in acre inches _per

acre Year 1990 1991 1992 1993 conventional 5 6 4 6 1 1 0 7 Suroe 1 5 1 5 0 4 0 03

Several reasons _may exist for the

_declining

_deep

_percolation

as shown in the above

data

11 Winter moisture and

_spring

rains _{may have left the} soil in the fields in a

condition conducive to

_packing

which increased the soil bulk

_density

Increased bulk

_density

reduces infiltration rates _{Weather conditions}

_during

the corn

_planting

seasons of 1992 and 1993 were such that

_they

inhibited work in corn fields This reduced

_tillage

lowered or minimized the loss of

stored soil moisture which reduced the amount of

_{early irrigation}

2 The farmers who

_requested

_surge units at the start of _{the program} were either the more innovative farmers or the ones with the most serious

irrigation problems

31

The _{last group of farmers} to _{request surge} units were more involved with

orchard _crops

_generally

orchard fields have shorter furrow rows are easier

to _manage under conventional

_irrigation

_{systems and may show less}

advantage

to the _{surge system} This is

_{supported by}

the data from field

I l CJ

M11 _{When this field} was

_{conventionally}

_irrigated

_{the run was}

split

in tl1e

middle but was

_{successfully irrigated}

_{in one run when}

surge

irrigated

Fewer side

_by

side

_comparisons

were _possible in the orchards

4

_Cooperative

Extension and Soil _{Conservation Service}

_personnel

_have

actively

promoted

_irrigation

water _{management concepts}

_by

_{personal visits} with water users _{newsletter articles}

_workshops

_{and demonstrations}

The values listed in the table _{may be}

_Questionably

low The numbers _may best be used to

_identify

trends that are _apparent

_During

_{each of the years there is a 3 1}

advantage

to _{the surge system}

_applications

_{Each year there is less}

deep

percolation

from _{either system} than

_during

the

_previous

_year These trends

indicate

_improved

_irrigation

water _management

_by

the _cooperators

_Cooperators

have also been warned of

_potential

salt build up if

adequate

_leaching

water is not used It is

_suggested

_they

take soil

_samples

on an annual basis for

_salinity

_analysis

to be aware _{of any} salt build _{up in their}

_irrigated

_fields

TILLAGE and SURGE

The bean field on farm E303 was _{divided into conventional}

tillage

and conservation

tillage

sectors In addition to _{surge and conventional}

_irrigation

_evaluations

were

made of wheel track and non wheel track furrow flows

Sediment content of run off waters were made from this field

_using

Imhoff cones conventional

_irrigation

Furrow

Deep

Ti llaqe Inflow outflow _{Infiltrated Dercolation}

Cony wheel 34 4 10 9 23 7 _{2 7}

Cony non wheel 38 0 8 2 29 8 9 0

Cons wheel 35 8 _{21 8 14 0 6}

9

Cons non _wheel 35 1 16 3 18 8 0 9

Surqe

irriqation

Furrow

Deep

Tillaqe

Inflow Outflow Infiltrated _Dercolation

Cony wheel 21 3 7 7 13 6 _{7 8}

Cony non wheel 19 8 3 9 16 0 _{4 5}

Cons wheel 23 7 6 6 17 0 4 4

Cons non wheel 20 9 7 5 13 4 _{8 0}

All of the above units are in acre inches per acre All set times were all 12 hours This reflects the less water

_applied

to _{the surge} sets where the water was divided

into the two

_surged

sets in the 12 hour

period

It is

_interesting

_{to note that more runoff and less infiltration}

occurred on the

conservation

_tillage

side of the

_{conventionally irrigated}

_portion

_{of the field than on}

the

_{conventionally}

_tilled

_portion

_{One would have}

expected

the

_opposite

to occur

L

I l 4

upon visual

inspection

of the field _great amounts of residue _{left from the previous}

crop of corn in the furrows created a _very

_rough

_{furrow structure}

which should

have led to

_impeded

_{flows and less runoff A}

possible explanation

to this

phenomenon

is that no

_tillage

was

_performed

on _{this side of the field rather the}

original

furrows and beds were

_simply

re

_shaped

_Some

_packing

_{of the surface}

soil may have occurred

_during

the re

_shaping

_{process which may have reduced}

infiltration of the

_irrigation

water

The fact that surge

irrigation

negated

the effect of

_tillage

or no

_tillage

on _infiltration

and runoff amounts is also of interest This result has

_significant

_implications

regarding

future _{procedures of crop residue}

handling

and surface

_irrigation

and

should be studied in detail

_{Surge irrigation}

_{may offer a}

significant

_advantage

when conservation

_tillage

_procedures

are

_applied

to a _surface

_irrigated

_field

The

_forty

_{percent reduction in water use obtained}

by

surge

irrigation

as

_compared

to conventional

_irrigation

on the field is of _great

_significance

_Explanations

_{for this}

occurrence _{have been elicited elsewhere}

Several reasons _{may exist for the}

apparent

large

negative

deep

percolation values This field site is located about 8 5 miles from _{the weather station that was used to}

generate the

_{evapotranspiration}

data used to estimate soil moisture _{deficits There}

is the

_possibility

of a micro climate

_change

between the two sites ET estimates

as used in the Grand

_Valley

_{may be}

_higher

_{than needed A water}

table condition

may exist on this site which would

_modify

the ET estimates for the field FOLLOWUP

Attempts

were made to contact _{each surge unit}

_recipient

_{to determine}

their

acceptance of _{the surge concept A}

_{questionnaire}

was used to _{document the} responses A _{copy is included}

_Responses

_{are summarized}

as follows

Acres in _surge sets

_ranged

from 2 to 8 _{while conventional}

companion

sets

_ranged

from 0 5 to 64 acres

Time to start a conventional set

_ranged

from 0 5 minutes to 120 _{minutes with} surge start time

_ranging

from 1 to 120 minutes

The various crops listed include alfalfa corn small

_grains

_{orchard and pastures}

The

_fertigation

_{concept is most useful on}

annual grass crops such as corn and 11

of the farmers used this method

Yield differences were not noticed

_by

the

_cooperating

_farmers

Fields were

_{probed by}

_{76 of the farmers}

r 3 If

l 4

Various methods were used to determine when to

_irrigate

_Many

farmers are on a

rotation _system so

_they

must

_irrigate

_{when the have a turn at the water These}

water users indicated that

_they

can

_complete

_their

_irrigation

_{in less time due to the}

use of the _{surge system}

Additional surge

equipment

was

_{purchased by}

23 of the farmers Most farmers 83 were comfortable

_using

_{the surge systems}

Most of the

problems

listed

_by

the

_respondents

were of a minor nature such as the outmost cover of _{the solar collector}

_peeling

_{off Several 3 had}

premature

battery

problems

Some of the comments

_by

users are included here

Great system

Some field

_slopes

and soil _types on Orchard Mesa _{make the} use of _surge

more

_complex

_{than it would} if the fields had a uniform

_Slope

and soil _type

Wished I could afford to convert whole farm to _surge

Runoff decreased better

_irrigation

of hard to

_irrigate

areas first

_irrigation

of

season on

_{newly plowed}

_{fields much more efficient}

Surge

is an _{excellent system should be used on all areas} Works

_good

A real work and water saver

Surge

computer needed

_repair

I _{would recommend the surge system to be used more} I think it is _great

While I haven t _{noticed any difference} in

_yields

a definite

_improvement

can

be seen in the trees at the end of the season I _{attribute this} to better

infiltration

due to _{the surge system and}

_especially

_{the information on the computer readout}

I would like to know how to

_gradually

set

_gates

_open more as the elevation

increases from the end cap to the _{surge valve} This is a real

_problem

with time

getting

a field to

_{irrigate properly}

_{until the} summer is over

We have

_only

had the

_opportunity

to use _surge one _{year Due to soil} conditions shale and

_length

of

_experience

_{with crop} rotation we had no

comparison

to _crop

_yields

I

_really

like

_using

_{the surge} as it doesn t leave a lot of tail water and over

soaking

on _part of the field

The _{surge system} has

_helped

_put a more uniform

_irrigation

Much easier and a _great time saver for me

Seems _very efficient

The surge system has cut the time and water use in half and am

_pleased

with more uniform tree

_growth

Surge

set

_requires

additional time as more area is

_getting

_irrigated

throws

off

_irrigation

schedule

Still

_trying

to use _my fields

_irrigation

_{with surge}

C J

Mol The surge sy aem saves me water _{and is also more}

efficient

as _{opposed to}

the _{traditional methods of}

_irrigation

We have been

_extending

the run on the _{surge side because we}

were not

getting enough

infiltration Saves water time

Works

_good

_{Uses 1 2 the water as}

compared

with _{conventional system or}

2 _{times the}

_ground

_{with same}

amount of water

Saves water

Works

_good

_{Saves time and water}

Controller

will not shut off valve

_completely

Excellent

system saves lots of time and _expense

Have trouble

_keeping

unit

_charged

Believe that the _{block that surge sets has not been}

correctly

leveled

_making

the surge erratic At end of

_irrigation

_{must go back and}

manually

override system

and

_irrigate

missed creases

If the _{system is}

_{managed properly}

_{it is}

very efficient If not it can cause

many

problems

work with

_sloping

_{land and the surge}

seems to _{work very well for me It}

has saved me time and uses less water to do the same

_job

Overall

_efficiency

_{is great less time to}

water and use less water

_probably

only

1 3 as much

_Deep

_{percolation eliminated not}

much run off

feel it works better on _{shorter field than}

long

runs

Trying

to use the

_quick

_{connect set screws we}

found the hole did not line

up

_consequently

the _{set screws were}

destroyed

_Being

unstable the unit moved

enough

to break _{the main gear in the controller}

Had to send it to Texas for

_repair

Couldn t use this summer because of a _{stuck valve}

Need individual

_{help programming}

surge valve

SURVEY

_SUMMARY

Information

from the _{survey sheets} was

_compiled

_{and it is}

projected

that

equipment purchased

_by

_{these grant funds is used on 1040}

acres of alfalfa 560 acres of corn

300

acres of small

_grains

and beans 150 acres of orchard _crops and on 50 acres _{of other crops}

including

pasture

The salt reduction from all acres due to the use of _{the surge}

_equipment

_is

projected

to be 1 617 tons in 1993 _{This reflects the}

averaged salinity

reduction over the

period

of the

_study

and the

_averaged

_{value of the salt}

contributions

from the 13

salinity

_contributing

areas _{in the Grand}

Valley

Local benefits include reduced

_irrigation

_applications

_fertilizer

savings

and the surge

equipment

in

_place

Total expenditures

_{for surge}

_equipment

_evaluation

equipment

seasonal labor for

GO H

C l

i

At the end of FY93 243 surge units had been

requested by

cooperators in the Grand

Valley

Unit as _part of the cost share

_approach

of the Colorado River

_Salinity

Control

_Program

An additional number of units not

_{readily quantifiable}

have been

purchased by

area farmers

_using

their own funds

_Nearly

all of these units are in

_place

because of the surge demonstrations in the area made

_possible

through

this

grant

and other Extension activities

c

IMPLICATIONS

The benefit to downstream water users is the 560 acre inches that was not

percolated through

the soil

profile

on the surge

irrigated portions

of the fields and

the resultant salt

_loading

reductions as shown

_by

the combined data This is the

measured total from the farms

irrigation

systems evaluated over _{the four year}

period

See column 12 of the attached data sheets under the

_heading

of acre inch reduction of

_deep

_percolation

This value is different than the

_projected

value calculated if all farms were measured at all

_irrigations

Note that 1 000 tons were

measured

during

the course of the

study

but that 1 617 tons were

_{projected during}

the 1993

_irrigation

season This difference is

partially

due to not

having

the

equipment

available to measure each

_irrigation

event

_during

the season on all farms and the

necessity

of

_averaging

salt load reduction values

Improved irrigation

water _management

_{by irrigators}

and or reduced

_application

rates due to

_{irrigation equipment}

hardware

changes

do not save water on basin

wide basis Those who _expect to harvest this saved water do not understand the

_{hydrological cycle}

I

i

Water that is

_deep

_percolated

_past the root _system in the Grand

_Valley

is

eventually

returned to the Colorado River for use downstream This time

period

is

variable but based on observations of the various

_drainages

in the

_valley

the

quantity

of water

_{deep percolated}

from

_irrigations

is back in the river

by

April

of

the

_following

year This water is

degraded

in

quality

but the

quantity

has not been

significantly

reduced The purpose of the Colorado River

Salinity

Control

Program

is to address water

_Quality

not

_Quantity

If less water is diverted because of better

_irrigation

water

_management

the flow will be available downstream at an

earlier date but there will not be more flow available While the water is

underground

in the

_irrigated

areas it is

_subject

to less

_evaporation

than while in the

major

reservoirs downstream this _concept is often overlooked

Deep

percolation

reduction made

_possible

by

surge units

purchased

with cost share

and

_private

funds is

beyond

the scope of this

study

but will be included as

_part

of

the total USDA

_salinity

reduction report

Water

_crossing

over from one

_irrigated

furrow to another

_prevented

accurate flow measurements on some fields This

implies

poor

irrigation

water _management

More

_frequent

and or

_deeper

furrowing

by

the farmer may

remedy

this

problem

J 1 l

An additional solution _{may be}

_leveling

on

_grade

_by

laser or

_{by conventionally}

controlled

_equipment

Silting

of the flow

_measuring

flumes _{may be} indicative of excess furrow flows a

steep

grade

poor furrow

compaction

high

silt load in the

_irrigation

water and or

recently

cultivated

_ground

Future studies should consider

_identifying

the cause

and

_quantifying

the amount of

_silting

_Adequate

_{manpower and}

_equipment

_to

measure the sediment content of the water

_during

an

_irrigation

are needed

1994 PLANS

The _grant from Bureau of Reclamation USDI has been used for this demonstration

and evaluation _program and has been terminated after 1993 Evaluation

equipment

will be available for use and continued

_irrigation

_{evaluations will be}

made

_using

_Cooperative

Extension funds

Plans for the 1994 _{crop year} include _{continued furrow flow evaluation immediate}

processing

of data and

_quick

return of the information to the farmer and increased

emphasis

on

_improved

water _management

_by

_{the cooperators}

Comparison

of nitrate

_nitrogen

sediment and

_phosphorous

contents of the tail

water of _{the surge} sets and conventional sets will be made when

_funding

is available

Results of the _surge

_fertigation

_program as noted in a

_previous

_report and

_irrigation

water _{management concepts as determined}

_by

the surge demonstration and evaluation _program will be stressed at

_meetings

and

o r o i f f INTERVIEW SHEET

How many acres are in _{the surge} sets

How many acres are in the conventional set

How much time does it take to start a conventional set i ow much time does it take to start the _surge sets

Crop

Have _you used the

_fertigation

_concept to

_apply

_nitrogen

fertilizer

Have _you noticed _any difference in

_yields

_{between the surge and conventional}

systems

Do you

probe

the _{top and bottom of the fields}

_during

_{or after}

irrigation

How _{do you} determine when to

_irrigate

Have you

purchased

additional _surge

_equipment

Are you comfortable

_adjusting

_{advance and cutback soak}

cycles

Have you

experienced

any

problems

with the _surge

_equipment

COMMENTS BY LJSER

J

Table 1

EFFECTS OF ONFARH WATER MANAGEMENT

The

_{hydro salinity}

model shows that

_deep

_percolation

is 11 inches

per year from 60 000 acres This

_equals

660 000 acre inches

55 000 acre feet of

_{deep percolation}

The associated salt load is 168 100 tons _{per year}

The unit factors for

_evaluating

salt load reduction

_resulting

from reduced

_{deep percolation}

are

canal Water Source tons ac in tons ac ft

1 East End Gov t

_Highline

0 474 5 69 2 Middle Gvv t

_Highline

0 263 3 16

3 _stage 1 Gov t

_Highline

0 341 4 09

4 West End Gov t

_Highline

0 234 2 81

5 Grand

_Valley

Canal 0 475 5 70

6 Grand

_Valley

_Highline

0 263 3 16

7 Grand

_Valley

Mainline 0 258 3 09

B _Independent Ranchman s 0 270 3 24 9 Kiefer Extension 0 350 4 20 10 Price Ditch 0 592 7 10 11 stub Ditch 0 592 7 10 12 Orchard Mesa No 1 0 280 3 36 13 Orchard Mesa No 2 0 280 3 36

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