Sprinkler system installation and monitoring of plant microclimate
by Douglas John Oellermann
A thesis submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE
in Agricultural Engineering
Montana State University
© Copyright by Douglas John Oellermann (1978)
Abstract:
A sprinkler irrigation system to irrigate 24 10 m. x 10 m. individual test plots of alfalfa and spring
wheat at precise rates was designed and installed. This was accomplished by using quick coupler
valves on the corner of each plot in conjunction with quick coupler keys using quarter-circle sprinkler
heads. Plots could thus be selectively irrigated for any chosen duration of time. The offseason use of
irrigation water was investigated, including late fall irrigation in spring wheat and alfalfa and early
spring irrigation on alfalfa, as well as normal seasonal irrigation. Parameters monitored included daily
maximum and minimum soil temperatures at 5 and 20 cm., soil moisture levels before and after
irrigation during the growing season and monthly during the dormant season, crop yields and weather
parameters such as daily maximum and minimum air temperatures, precipitation, solar radiation, wind
run, relative humidity and standard pan evaporation. The project investigated the efficiency of storage
of water in the off-season, the effects of off-season irrigation on soil temperature regimes and crop
yield and possible energy or equipment savings by lengthening of the irrigation season. The
relationship between spring wheat yield and total water applied during the 1977 season was evaluated.
A second order regression equation with r2 = 0.7804 was determined which indicates that yield
increases with increased water to a certain point, then decreases.
Some plots had a gross gain in water over-winter while others had a gross loss. No relationship could
be established. The efficiency of irrigation water storage over-winter was calculated for the plots. The
spring wheat plots had higher overall efficiencies than the alfalfa since the former were drier prior to
fall,irrigation. Positive spring wheat efficiencies ranged from 43-65%. Alfalfa efficiencies were all
negative with one exception, 25%. Negative efficiencies indicate more water was lost than was applied
by irrigation. Fall irrigation is beneficial if the soil profile is dry prior to fall irrigation and spring
precipitation and runoff are not excessive.
/ STATEMENT OF PERMISSION TO COPY
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requirements fo r an advanced degree a t Montana State U n iv e rs ity ,
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It
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Signature
Date
/j
/ 9% )
SPRINKLER SYSTEM INSTALLATION AND MONITORING
OF PLANT MICROCLIMATE
by
DOUGLAS JOHN OELLERMANN
A th e s is submitted in p a r tia l f u lf illm e n t
o f the requirements fo r the degree
■
Of
MASTER OF SCIENCE
'in
A g ric u ltu ra l Engineering
Approved:
"Chairman, Graduate Committee
Head, Major Department
MONTANA STATE UNIVERSITY
Bozeman, Montana
August, 1978
iii
ACKNOWLEDGMENT
I would lik e to thank my p a re n ts , Mr. and Mrs. Ve,rnon C.
Oellermann, fo r th e ir help and patience.
I also wish to thank my major
a d v is o r. Dr. T. L. Hanson, who aided me in innumerable ways and helped
make th is p o ssib le .
I fu r th e r thank the o th e r two members o f my
graduate committee. Dr. C. M. M ilne and Dr. R. L. B ru s tk e rn , fo r th e ir
suggestions and help.
P ro je c t 2-6000-564 is funded by the O ffic e o f
Water Research and Technology under the Water Resources Act o f 1964
(P u b lic Law 88-379) through the Water Resources I n s t it u t e a t South .
Dakota State U n iv e rs ity , Brookings, South Dakota.
TABLE OF CONTENTS
CHAPTER
I.
Page
BASIS OF INVESTIGATION................................. ... ...................................
STATEMENT OF PROBLEM........................ ........................... ....
2
CM CM CO CO
Storage o f I r r ig a t io n Water .................... .
E ffe c ts on S o il Temperatures........................
E ffe c ts on System S iz e ....................................
C lim a to lo g ica l E ffe c ts . .................... ... . .
CO
REVIEW OF SELECTED LITERATURE ................
«3- LO
Storage E ffic ie n c ie s ............................ ....
S oil Water Movement................................ .
.
S oil M oisture Stress E ffe c ts on
Spring Wheat and A l f a l f a ................ ... . .
Optimum S oil Temperatures f o r Crop Growth
S o il Temperature Changes due to Ir r ig a tio n
C u ltiv a tio n and I r r ig a tio n o f Crops . " ............................
S o il M oisture D epletion--Jensen Equation.....................................
C onclusion...........................................................................................
10
13
13
DEFINITIONS...........................................................................................
14
PROCEDURES................................................ ...
["-« CO O V I
2.
I
16
J '
LOCATION AND SOIL PROPERTIES.........................................................
16
DISPOSITION OF PLOTS AND TREATMENTS ................
16
. . . . . . .
IRRIGATION SYSTEM..................................................................................... 19
INSTRUMENTATION...................................................................................
S oil M oisture Measurement . . . . .
S oil Temperature Measurement. . . .
C lim a to lo g ica l V ariable Measurement
Y ie ld Measurement........................ ... .
3.
22
22
25
25
25
RESULTS.......................................................................................................
YIELD VS. WATER APPLIED RELATIONSHIPS—1977 SEASON................
CONDITIONS OF FALL IRRIGATION
-2 6
32
-V r
CHAPTER
Page
MIGRATION OF SOIL WATER OVER-WINTER.................................... : .
36
GAIN OR LOSS OF SOIL WATER OVER-WINTER........................................ ..
36
Water Storage in Spring W h e a t........................................................
Water Storage in A l f a l f a ....................................................................
A d d itio n a l Data from South Dakota ................................................
4.
42
46
46
WATER STORAGE EFFICIENCIES VS. PERCENT FIELD CAPACITY . . .
48
RELIABILITY OF DATA ' .............................................................................
49
CONCLUSIONS ....................................................
................
. . . . . .
52
YIELD VS. WATER APPLIED........................................................
i' '
WATER STORAGE EFFICIENCIES..........................................................
52
52
WATER STORAGE EFFICIENCIES' VS. PERCENT FIELD CAPACITY . . .
5.
SUMMARY . . . . . . .
53
..............................................................
54
PROCEDURES........................................................ ................... ....
54
YIELD VS. APPLIED WATER............................ ' ......................................
54
DISPOSITION OF SOIL WATER OVER-WINTER................................ ...
55
.
STORAGE EFFICIENCIES...............................
55
RECOMMENDATIONS FOR FURTHER RESEARCH................................................
CONCLUSIONS........................
SELECTED BIBLIOGRAPHY
56
.................... ...........................................
57
.............................. ...................................................
58
APPENDIX--Summary o f O ver-w inter M oisture Levels in
Spring Wheat and A lf a lf a — 1977-78 Season................................
62
vi
LIST OF TABLES
Table
1.
Page
Water Holding P roperties and Bulk D ensities o f
Amsterdam S ilt y Clay Loam a t Research S ite .................................
2.
D escrip tion o f I r r ig a tio n T re a tm e n ts ..................... ■..................
3.
C u ltu ra l P ractices on Spring Wheat—1977-78 Season....
4.
C u ltu ra l P ractices on A lf a lf a —1977-78 Season . . . . . . .
5.
Log o f S oil M oisture Readings on
Spring Wheat— 1977-78 Season............................................................
17
18
27
28
Log o f S oil M oisture Readings on
A lf a lf a —1977-78 Season ....................................................
i’
7. Amount o f Water Applied to Spring Wheat, cm.--1977 Season .
29
6.
30
31
8.
Spring Wheat Y ie ld Data—1977 Season................................
33
9.
Average Spring Wheat Y ie ld by Treatment—1977 Season. . . .
34
10.
P re c ip ita tio n Summary—Bozeman 6W S t a t i o n ........................ ...
43
11.
Water Storage E ffic ie n c y in Spring Wheat........................
12.
Water Storage E ffic ie n c y in A lfa lfa ........................
45
47
v ii
LIST OF FIGURES
Figure
Page
1.
Schema o f Research P lo ts ....................................................................
20
2.
Research I r r ig a tio n System........................................................ ■ . •
21
3.
Two-Inch Coupler w ith Double Valve R is e r....................................
23
4.
Two-Inch Coupler w ith Double Valve Riser
With Keys and S p rin k le r Heads In s e rte d .......................................
23
5.
I r r ig a tio n System in O peration............................................................
24
6.
Y ie ld vs. Applied Water C o rre la tio n , Spring Wheat 1977. . .
35
D is p o s itio n of- M oisture in S oil P ro file s Over-W inter. . . .
i'
8. Water Storage E ffic ie n c ie s vs. Percent
F ie ld Capacity P rio r to I r r ig a t io n ................................ . . . .
37
7.
50
v iii
ABSTRACT
A s p r in k le r ir r ig a t io n system to ir r ig a t e 24 10 m. x 10 m.
in d iv id u a l te s t p lo ts o f a lf a lf a and sp rin g wheat a t precise rates
was designed and in s ta lle d . This was accomplished by using quick
coupler valves on the corner o f each p lo t in con junctio n w ith quick
coupler keys using q u a rte r-c irc le s p r in k le r heads. P lots could thus
be s e le c tiv e ly ir r ig a te d fo r any chosen d u ratio n o f tim e . The o f f ­
season use o f ir r ig a t io n water was in v e s tig a te d , in c lu d in g la te f a l l
ir r ig a t io n in sprin g wheat and a lf a lf a and e a rly sp rin g ir r ig a t io n
on a l f a l f a , as w ell as normal seasonal ir r ig a t io n . Parameters
monitored included d a ily maximum and minimum s o il temperatures a t 5
and 20 cm., s o il m oisture le v e ls before and a fte r ir r ig a t io n during
the growing season and monthly during the dormant season, crop y ie ld s
and weather parameters such as d a ily .maximum and minimum a i r tempera­
tu re s , p r e c ip ita tio n , s o la r ra d ia tio n , wind ru n , r e la tiv e hum idity
and standard pan evaporation. The p ro je c t in v e s tig a te d the e ffic ie n c y
o f storage o f water in the o ff-s e a s o n , the e ffe c ts o f off-season
ir r ig a t io n on s o il temperature regimes and crop y ie ld and possible
energy or equipment savings by lengthening o f the ir r ig a t io n season,
the re la tio n s h ip between sp rin g wheat y ie ld and to ta l w ater applied
during the 1977 season was evaluated. A second order regression
equation w ith r 2 = 0.7804 was determined which in d ic a te s th a t y ie ld
increases w ith increased water to a c e rta in p o in t, then decreases.
Some p lo ts.h a d a gross gain in water o v e r-w in te r w h ile others had
a gross lo s s . No re la tio n s h ip could be e sta b lish e d . The e ffic ie n c y
o f ir r ig a t io n water storage o v e r-w in te r was ca lc u la te d f o r the
p lo ts . The sp rin g wheat p lo ts had higher o v e ra ll e ffic ie n c ie s than
the a lf a lf a since the form er were d r ie r p r io r to f a l l , i r r i g a t i o n .
P o s itiv e sp rin g wheat e ffic ie n c ie s ranged from 43-65%. A lfa lfa
e ffic ie n c ie s were a ll negative w ith one exception, 25%. Negative
e ffic ie n c ie s in d ic a te more water was lo s t than was a p p lie d .b y
ir r ig a t io n . F a ll ir r ig a t io n is b e n e fic ia l i f the s o il p r o f ile is
dry p r io r to f a l l ir r ig a t io n and sp rin g p r e c ip ita tio n and ru n o ff
are not excessive.
"
Chapter I
BASIS OF INVESTIGATION
As water becomes more and more valuable in man's d a ily l i f e ,
every drop must be u tiliz e d to i t s maximum.
A g ric u ltu re is in in c re a s ­
ing com petition w ith in d u s try , re c re a tio n , w i l d l i f e , m u n ic ip a litie s and
many o th e r in te re s ts fo r the use o f a renewable, but annua lly f i n i t e
resource.
Even in the West, where ir r ig a t o r s have enjoyed almost
e xclu sive use o f the w aters, in d u s trie s , e s p e c ia lly en e rg y-re la te d
companies, are demanding and re c e iv in g rig h ts to the use o f these
i'
w aters. . Ir r ig a to r s are in c r e a s in g ly - e ffic ie n t w ith t h e ir lim ite d
r ig h ts , due to modern s p r in k le r systems and b e tte r u t iliz a t io n o f
e x is tin g systems.
By knowing the p ro p e rtie s o f the s o ils under i r r i g a ­
tio n and.m onitoring the s o il m oisture le v e ls , they can apply the r ig h t
amount a t the r ig h t tim e.
There is always room fo r improvement to any system.
One such
improvement suggested is to u t i l i z e waters not norm ally used fo r i r r i ­
g a tio n .
These are waters now going down the stream from f a l l and sp rin g
p r e c ip ita tio n and e a rly sp rin g snow m e lt.
Can f a l l and sp rin g applied
water be stored in the s o il f o r seasonal use?
a tta in e d ?
What e ffic ie n c ie s can be
This th e s is w i l l address some o f these questions.
2
STATEMENT OF PROBLEM
The problem is to determine the f e a s i b i l i t y o f off-season i r r i ­
gation ( i . e . , la te f a l l and e a rly sp rin g ir r ig a tio n s ) on ir r ig a te d crops
in r e la tio n to the d is p o s itio n o f off-season applied water in the s o il
p r o f ile , s o il tem peratures, c lim a tic v a ria b le s , system size and power
requirem ents.
Storage o f I r r ig a t io n Water
Can ir r ig a t io n water applied during the off-season be stored
fo r seasonal use?
much.
Is i t
I f i t can be s to re d , i t is im portant to know how
e ff ic ie n t?
Water which is stored in the s o il can be used
as a reserve to draw upon during peak demand periods when the i r r i g a ­
tio n system cannot supply a l l o f the c ro p 's demands.
This is analogous
.i
to a c i t y water system when both the w ater re s e rv o ir and the pumping
s ta tio n supply the needs a t peak use. ra te s .
E ffe c ts on S oil Temperatures
W ill s o il temperatures be adversely a ffected ?
an optimum s o il temperature a t which they grow the b e s t.
A ll crops have
S oil tempera­
tures which are s ig n if ic a n t ly lowered could have a harmful e ffe c t on
the crop, reducing y ie ld s and thus adding to the cost o f off-season
ir r ig a t io n .
3
E ffe c ts on System Size
W ill a savings be re a liz e d by using a sm a lle r system over a
longer period o f tim e , th a t i s , both in-season and off-season?
A
sm a lle r system w i l l use less energy per hour, but the d u ra tio n o f use
is lo n g e r.
The same to ta l amount o f w ater f o r a c e rta in crop s t i l l
needs to be s u p p lie d , be i t in-season, o r o ff-sea son.
C lim a to lo g ica l E ffe c ts
The v a ria tio n s o f clim a te from one year to the next w i l l c e r­
t a in ly have s ig n ific a n c e on the p r a c t ic a b ilit y o f off-season ir r ig a t io n .
What are the e ffe c ts o f a dry f a l l o r a wet sprin g on th is p ra c tic e , o r
vice-versa?
These questions need to be answered:
REVIEW OF SELECTED LITERATURE
‘
In order to understand b e tte r what is known on the sub ject and
to id e n tify areas la c k in g in knowledge, several areas were reviewed.
It
is o f in te r e s t to in v e s tig a te research already done in such areas as the
e ffic ie n c y o f storage o f f a l l and sp rin g applied w ate r, the movement o f
water in the s o il p r o f ile in a ll seasons, and the s o il m oisture re q u ire ­
ments o f crops and the e ffe c ts o f s o il moisture stre ss on them .. Also
o f in te r e s t are the optimum growing temperatures o f crops, the e ffe c t
o f ir r ig a t io n on s o il temperatures and the s p e c ific e ffe c ts o f these
4
va ria b le s on sprin g wheat and a l f a l f a , the crops to be grown in th is
experiment.
Storage E ffic ie n c ie s
I t is o f prim ary in te r e s t to know how much w ater due to an o f f ­
season f a l l o r sp rin g (preseason) ir r ig a t io n is stored in the s o il and
u t iliz e d .
I t has been found th a t carryove r from f a l l to sp rin g is
a ffe c te d by the s o il m oisture content (Timmons, 1968).
Moreover, Hobbs
(1971) sta te s th a t the storage e ffic ie n c y is in v e rs e ly re la te d to s o il
m oisture content..
F a ll i r r i g a t i o n .
found fo r f a l l ir r ig a t io n .
A v a rie ty o f storage e ffic ie n c ie s have been
In Saskatchewan, Staple (1960) determined
an e ffic ie n c y o f 37% on stubble fie ld s w h ile Timmons (1968) estim ated
th a t 1/3 o f the to ta l dormant season p r e c ip ita tio n in Minnesota was
sto re d .
A s im ila r 31% e ffic ie n c y was found in a dry p r o f ile by Hobbs
(1971).
A la te f a l l ir r ig a t io n in Texas y ie ld e d a high 54% e ffic ie n c y
(Musick, 1971).
Raney (1960) says th a t from te s ts made from 1953-57
in Kansas, he can conclude th a t f a l l ir r ig a t io n is p r o fita b le in a dry
fa ll.
I t would appear th a t as much as I /3 -1 /2 o f w ater applied to a
dry s o il p r o f ile in the f a l l can be conserved o v e r-w in te r.
The amount
conserved is a fu n c tio n o f the s o il m oisture le v e l a t the time o f
ir r ig a t io n .
5
Preseason i r r i g a t i o n .
Preseason ir r ig a t io n e ffic ie n c ie s are
s im ila r to those o f f a l l ir r ig a t io n .
In order to increase e ffic ie n c ie s ,
Musick (1970) suggests c u ttin g o f f seasonal ir r ig a t io n a t an e a rly date,
no la t e r than e a rly g ra in f i l l i n g , , to dry out the p r o f ile .
As in f a l l
ir r ig a t io n , the e ffic ie n c y was highest when the s o il m oisture content
was low est.
Musick (1971) also sta te s th a t low evaporative p o te n tia l
a t the time o f ir r ig a t io n raised e ffic ie n c ie s .
In th is te s t , the e f f i ­
cie n cie s were believed to be a ffe c te d by low s o il p e rm e a b ility and
d i f f i c u l t y o f w e ttin g the s o il to a considerable depth. Musick (1970)
i'
found e ffic ie n c ie s o f stored r a in f a ll o f 30-50% on dry s o ils to 10% on
wet s o ils .
1971).
A la te sp rin g ir r ig a t io n y ie ld e d -a 33% e ffic ie n c y (Musick,
He also sta te s th a t preseason ir r ig a t io n did not appreciably
increase y ie ld s , but did delay the need f o r e a rly seasonal ir r ig a t io n
one out o f three years.
Again, 1 /3 -1 /2 o f sp rin g applied w ater, be i t r a in f a ll o r i r r i ­
g a tio n , was conserved in a dry p r o f ile .
The e ffic ie n c ie s drop dras­
t i c a l l y in a wet p r o f ile , since the ap p lie d water is p a r tly lo s t to
deep drainage.
■
S oil Water Movement
Frozen s o i l . . The e ffe c ts and movement o f w ater in the s o il
a ft e r f a l l ir r ig a t io n through the w in te r season is o f in te r e s t.
It
has been found th a t dry s o ils freeze deeper and fa s te r than wet s o ils
6
and th a t the form er thaws upward w hile the l a t t e r thaws from both
d ire c tio n s ( W illis , 1961).
The p e rc o la tio n ra te o f w ater in frozen
s o il decreases w ith incre asing m oisture con ten t.
When the s o il is
a lte rn a te ly frozen and thawed, there is no change in the p e rc o la tio n
ra te a t 15 atmospheres pressure, an increase in the ra te a t f i e l d
cap acity and a decrease in the p e rc o la tio n ra te a t high m oisture con­
te n ts (0.1 a tm .).
The decrease a t high m oisture contents is believed
due to the d e s tru c tiv e e ffe c ts o f fre e z in g and thawing on the s o il
aggregates (Hinman, 1973). Ferguson (1964) states th a t a t depths in
i'
frozen s o il as deep as 180 cm. and 235 cm., water held a t low tensions
(5 atm .) moved to the frozen zone from the unfrozen zone.
For every
centim eter o f a v a ila b le w ate r, a decrease o f 0.22 cm. o f stored water
was found.
I f the s o il p r o f ile is below o r equal to f i e l d cap acity a t the
time o f fre e z in g in the f a l l , i t appears th a t water may be frozen w ith ­
out d e le te rio u s e ffe c ts .
Deep draina ge.
The movement o f w ater in the s o il p r o file
should also be considered to help determine where the w ater losses
occur.
M ille r (1971) ascertained th a t deep drainage decreased as
e va p o tra n sp ira tio n increased.
In a 31-day f i e l d stud y, 6 cm. o f w ater
was lo s t to deep drainage in a 150 cm. p r o f ile .
I t was also found th a t
there was an upward movement o f w ater whose ra te reached a maximum o f
7
0.20 cm./day (Stone, 1973).
W ilcox (1959) discovered th a t w ith in ­
creased depth, the to ta l drainage increased, but the net ra te o f loss
per meter decreased.
M ille r (1972) performed te s ts which showed a .
delay between the end o f ir r ig a t io n and the s ta r t o f drainage.
Van
Schaik (1970) noted th a t on Chin loam and Cavendish loamy sand s o ils ,
much o f the s o il m oisture loss over w in te r is due to the c a p illa r it y
o f the s o i l .
S oil M oisture Stress E ffe c ts on
Spring Wheat and A lfa lfa
i"
What are the e ffe c ts o f s o il m oisture stre ss on a crop?
Dubetz
(1970) sta te s th a t w ith in cre asing s o il m oisture in sp rin g wheat, an
increase in y ie ld but a decrease in p ro te in content was achieved.
In
a l f a l f a , lower temperatures and low s o il m oisture stress.gave a higher
y ie ld and d i g e s t i b i l i t y o f a lf a lf a
(Vough, 1971).
Constant s o il mois­
tu re stre ss has a tendency to lower the y ie ld approxim ately as a lin e a r
fu n c tio n o f the s e v e rity o f s tre s s .
The magnitude o f re ductio n o f
y ie ld from occasional stre ss is dependent on the e v a p o tra n sp ira tio n
ra te , the s e v e rity o f stre ss and most im p o rta n tly , the p h y s io lo g ic a l
stage o f growth o f the p la n t.
The most c r i t i c a l p h y s io lo g ic a l stage is
from flo w e rin g to m a tu rity (Downey, 1972).
Lucey (1965) found th a t fo r
forage , the m oisture absorption is g re a te s t in the upper 15 cm. o f s o il.
/
The absorption decreases when the s o il m oisture reaches less than 25-30%
8
o f the a v a ila b le m oisture and a t.a value o f less than 15%, p la n t stre ss
is apparent.
Since i t is obvious th a t causing m oisture s tre ss during the
repro ductive stage o f the p la n t reduces y ie ld s , one w i l l have to be
c a re fu l a t which stage he cuts o f f ir r ig a t io n in order to dry out the
p r o f ile , as suggested by some in v e s tig a to rs .
Optimum S oil Temperatures fo r
Crop Growth
The a p p lic a tio n o f off-season ir r ig a t io n is expected to have an
i ’
'
e ffe c t on so.il tem perature.
e ffe c t on p la n t growth.
Such changes may o r may not have an adverse
Various in v e s tig a to rs have determined optimum
temperatures fo r the growth o f d iffe r e n t crops..
Mack (1965) found th a t
b a rle y , regardless o f s o il m oisture , grew best a t 18°C.
For spring
wheat. Mack (1973) determined a range o f 10-18°C fo r optimum growth,
w h ile temperatures from 18-28°C s ig n if ic a n t ly reduced y ie ld s .
Sosulski
(1966) re p o rts th a t Thatcher wheat y ie ld e d more a t 18°C than a t 24°C.
Smika (1974) tested two sp rin g wheat v a r ie tie s , Lee and Crim, and found
a somewhat lower optimum s o il temperature a t crown depth, 12.5 and
14.5°C, re s p e c tiv e ly , than o th e r in v e s tig a to rs .
Wheat emergence was
100% a t 20-25°C w h ile i t was very low a t 5°C (Singh, 1972).
In y e t
another experim ent, B oatw right (1976) found th a t sp rin g wheat has an
optimum surface s o il temperature (0-3 cm.) o f 19-22°C.
At less than
these tem peratures, y ie ld s were reduced s ig n if ic a n t ly .
He fu r th e r
9
sta te s th a t the crown seems to be the most s e n s itiv e p a rt o f the p la n t
to low s o il tem peratures.
For b a rle y . Power (1963) determined an
optimum temperature o f 15°C.
A lf a lf a , subjected to day and n ig h t tem­
peratures o f 18° and 10°C, re s p e c tiv e ly , gave higher y ie ld s than when
under a 32/24°C regime (Sm ith, 1969).
For sp rin g g ra in s , a mean optimum temperature o f 18°C appears
to be the best.
A wide range was found which re s u lte d in optimum tem­
peratures from 10-25°C.
A lfa lfa has not been tested as e x te n s iv e ly but
a reasonable value would also be in the 18°C range f o r optimum growth.
i"
S oil Temperature Changes Due to
Ir r ig a tio n
Several in v e s tig a to rs have measured s o il temperature changes due
to ir r ig a t io n .
At a 10 cm. depth, s o il ir r ig a te d d a ily was 2°C below
th a t o f a s o il which had been ir r ig a te d one week e a r lie r (K ohl, 1973).
Wierenga (1971) sta te s th a t s o il temperatures a t 5 and 10 cm. depths
were a ffe c te d fo r less than 24 h rs. by warmer (27°C) and co o le r (14°C)
ir r ig a t io n w ater.
At a depth o f 30 cm ., the e ffe c ts o f the co o le r and
warmer water la s te d less than 60 h rs.
He also found th a t s o il tern- ■
peratures were reduced by evaporative c o o lin g in m id -A p ril but not in
m id-February.
He concludes th a t e a rly sp rin g ir r ig a t io n would delay
warming o f the s o il p r o f ile .
In New York on fo re s t s o ils , Leonard
(1971) measured the e ffe c ts o f w ater which was 0 - 5 .5°C warmer than the
surface tem perature.
He found, a t the 300 cm. depth, th a t the s o il
y
10
warmed to IO0C 1-1% months sooner than nontreated areas and the s o il
cooled to IO0C about one week la t e r than non-treated areas.
The e ffe c ts o f water temperature on the s o il temperature depends
on whether the water is o f a higher o r lower temperature than the s o il.
Using warm w ater warmed up the p r o f ile sooner w h ile co o le r water w i l l
tend to delay warming o f the p r o f ile .
This needs to be in v e s tig a te d
more thoroughly.
C u ltiv a tio n and I r r ig a t io n
o f Crops
i'
■
A l f a l f a . The ir r ig a t io n and c u ltiv a tio n o f a lf a lf a and sprin g
wheat is im portant to understand.
D itte r lin e (1976) recommends an i r r i ­
gation on a lf a lf a in Montana before f a l l freezeup and 2-3 seasonal
ir r ig a t io n s .
He adds th a t an ir r ig a t io n e a rly in the sp rin g is d e s ir­
able unless there is a v a ila b le m oisture.
However, another in v e s tig a to r
states th a t the f i r s t sp rin g ir r ig a t io n should be delayed u n til the
s o il warms up (S tanberry, 1955).
Daigger (1970) found th a t, in western
Nebraska, the average e v a p o tra n s p ira ti on r a tio over a th re e -y e a r period
was 680.
I t was found th a t the f i r s t c u ttin g was.most p r o fita b le .
Daigger recommends f i l l i n g the s o il p r o f ile to a depth o f 2.5 m. e a rly
in the season.
E vapo tra nspira tion va rie s throughout the season and i t
is thought th a t i t increases from e a rly sprin g to la te s p rin g , then
decreases through the summer.
A dvection, the h o riz o n ta l movement o f
d r ie r a i r over a cro p , is an im portant fa c to r which c o n trib u te s to the
11
la te sprin g peak (Rosenberg, 1969).
With three d iffe r e n t le v e ls o f
ir r ig a t io n through three seasons in southern A lb e rta , Krogman (1965)
determined e va p o tra n sp ira tio n rates o f 0.31-0.91 cm./day w ith an
average o f 0.51 cm./day.
D itte r lin e (1976) emphasizes the importance
o f avoiding severe s o il m oisture stre ss in a lf a lf a w h ile p e rm ittin g
slow, steady growth.
With water in the s o il p r o f ile immediately before
freezeup, heaving o f the s o il may be a problem.
Stanberry (1955) sta te s
th a t w in t e r k illin g is dependent on v a r ie ty , p la n t v ig o r, the s o il
m oisture and s o il type.
I
-
S o ils which are fin e -te x tu re d and saturated
’
heave p la n ts , le a vin g them exposed to low temperatures and dessic a tio n .
In w e ll-d ra in e d s o ils , the problem o f heaving is less se rio u s .
Holmes
(1960) determined th a t the s e v e rity o f heaving a t Ottawa, Canada,
increases w ith a lte rn a te thawing and fre e z in g , which moves water to
the s o il surface.
A la y e r o f snow is good p ro te c tio n ag a in st occur­
rences o f th is type.
In a po orly drained s o il in I l l i n o i s , Portz (1967)
found th a t damage due to heaving was moderate to severe in a moderate
w in te r.
S o ils a t o r near f i e l d ca p a c ity seemed to be more s u s c e p tib le .
I f a s o il is w e ll-d ra in e d where heaving is not a problem, f a l l
ir r ig a t io n may be fe a s ib le .
E arly sp rin g ir r ig a t io n may also be
d e sira b le i f there is a shortage o f water in the p r o f ile to take advan­
tage o f e f f ic ie n t water use by a lf a lf a e a rly in the season.
Spring wheat.
E arly sp rin g ir r ig a t io n o f s p rin g wheat a t
Pullman, Washington, p r io r to the boot is not economical unless w ilt in g
12
is e v id e n t, according to Robins (1962).
V
I t has been recommended to
ir r ig a t e w in te r wheat in the f a l l to a depth o f 180 cm ., thereby
avoiding e a rly sprin g (March and A p r il) ir r ig a t io n (Grimes, 1962).
He
fu r th e r sta te s th a t ir r ig a t io n is b e n e fic ia l a t the boot stage i f r a in ­
f a l l is below normal and is e s p e c ia lly necessary a t the m ilk stage in
extrem ely dry years.
Dougherty (1974) a rriv e d a t a ra th e r s u rp ris in g
conclusion th a t ir r ig a t io n o f wheat in New Zealand ju s t before and
a fte r ear emergence reduced y ie ld s .
Robins (1962) re p o rts th a t m oisture
stre ss caused y ie ld reductions o f 10-35% and was maximum during and
i'
a ft e r heading. He adds th a t the s o il m oisture should not be t o t a l l y
depleted before m a tu rity .
El Nadi (1969) supports th is fin d in g in
re p o rtin g from the Sudan th a t flo w e rin g , g ra in f i l l i n g and m aturation
are more s e n s itiv e to m oisture stre ss than the ve g e ta tive phase o f
p la n t development.
In comparing one f a l l ir r ig a t io n w ith one spring
ir r ig a t io n , Koehler (1974) re p o rts th a t the la t t e r y ie ld e d 9 q/Ha. more
than the former a t Pullman, Washington.
sprin g ir r ig a t io n on w in te r wheat during
Kansas.
Raney (1960) recommends e a rly
a
dry sprin g in north c e n tra l
However, he adds, care must be taken to prevent lodging i f '
r a in fu l I should occur a f t e r ir r ig a t io n .
I t appears to be questionable i f e a rly sp rin g ir r ig a t io n o f
sprin g wheat is d e s ira b le .
Most in v e s tig a to rs do not recommend i t save
in case o f a severe w ater shortage because o f the delay in warming the
s o il p r o f ile .
F a ll ir r ig a t io n may be a b e tte r a lte r n a tiv e .
Hobbs
13
(1971) notes th a t a t V auxh all, A lb e rta (p. 17):
Spring ir r ig a t io n is not fe a s ib le throughout most o f the
area because w a te r-is not a v a ila b le in the d is tr ib u tio n systems.
I t is also d i f f i c u l t to ir r ig a t e u n ifo rm ly and adequately the
bare s o ils o f unseeded o r newly seeded f ie ld s . Consequently,
in the ir r ig a te d areas o f the Canadian p r a ir ie s , i f f a l l s o il
m oisture content is in the lower h a lf o f the a v a ila b le range,
i t is advisable to f a l l - i r r i g a t e .
Musick (1971) says o f preseason ir r ig a t io n on sorghum on the southern
High P lains o f Texas (p. 97):
Preseason ir r ig a t io n did not in flu e n c e grain y ie ld s .
appre ciably where a ll treatm ents received the same two o r three
s e a s o n a l.irrig a tio n s . Preseason ir r ig a t io n , which increased .
to ta l ir r ig a tio n - w a te r a p p lic a tio n by o n e -fo urth to o n e -th ird ,
was i n e f f ic ie n t ly used fo r gra in production and reduced the
w ater use e ffic ie n c y o f to ta l ir r ig a t io n water a p p lie d .
S oil M oisture Depletion--Jensen
Equation
.
'
Numerous equations have been form ulated to p r e d ic t lS oil m oisture
d e p le tio n .
parameters:
Jensen (1969) developed one such equation based on fo u r
( I ) d a ily minimum and maximum a ir tem peratures,
(2) d a ily
s o la r ra d ia tio n , (3)' average dew-point temperature a t 8:00 a .m ., and
(4) d a ily wind run a t a known h e ig h t.
He states th a t in the absence o f
parameters 3 and 4, a two-parameter equation based on parameters I and
2 can be used i f advection is not severe.
Conclusion
From previous research, most areas o f in te r e s t to the present
p ro je c t have been in v e s tig a te d to some e x te n t.
The question o f seasonal
14
carryove r has been p a r t ia lly answered..
Whether the e ffic ie n c ie s already
determined are high enough to make off-season ir r ig a t io n economical
remains to be seen.
Much work has to be done y e t in determ ining the
e ffe c ts o f lowered s o il temperatures on crops.
Some work has been done
on optimum temperatures fo r crops and on the changes on so il"te m pe ratu redue to ir r ig a t io n , but a combination o f the two e ffe c ts has not been
stu d ie d .
Findings seem to in d ic a te th a t ir r ig a t io n system size may not
be a ffe c te d to a la rg e e x te n t, but th is needs to.be determined more
th o rou gh ly.
With the data from the experim ent, some o f the now-
unanswered questions should be s a tis fie d .
DEFINITIONS
A v a ila b le m oisture—Total s o il m oisture a v a ila b le f o r p la n t use as
determined by the d iffe re n c e in measured s o il m oisture le v e l
and w ilt in g p o in t.
E ffic ie n c y o f o v e r-w in te r Storage--The amount o f f a ll- a p p lie d water
stored in the s o il p r o f ile o v e r-w in te r d iv id e d by the to ta l
amount o f f a l l ir r ig a t io n , m u ltip lie d by 100.
F ie ld c a p a c ity --M o is tu re content o f s o il a ft e r g ra v ita tio n a l water is
removed, u su a lly two days a ft e r ir r ig a t io n .
Gain - r a t i O--The r a tio o f p r e c ip ita tio n stored in the s o il p r o file to •
the to ta l p r e c ip ita tio n received during a p e riod .
Late f a l l ir r ig a t io n —A p p lic a tio n o f water to the s o il a ft e r removal o f
the crop and before fre e z in g w ith the in te n t o f s to rin g a por­
tio n of. the w ater o v e r-w in te r fo r seasonal use.
Preseasoh ir r ig a tio n - - E a r ly sp rin g ir r ig a t io n a fte r thawing o f the s o il
p r o f ile but before a c tiv e growing o f the cro p, w ith the in te n t
o f s to rin g a p o rtio n o f the w ater f o r seasonal use.
S oil p ro file --T h e p o rtio n o f the s o il from which the ro o ts o f the p la n t
a c tiv e ly withdraw w ater.
W iltin g p o in t—M oisture content o f s o il a t which p la n ts can no longer
i ''
remove w ater.
Chapter 2
I
PROCEDURES
The experimental procedures and physical c h a ra c te ris tic s o f the
p ro je c t heed to be o u tlin e d to.gain , a b e tte r understanding o f the basis
fo r the re s u lts o f the experim ent.
These include the lo c a tio n , s o il
p ro p e rtie s , p lo t la y o u t, ir r ig a t io n system and in stru m e n ta tio n to moni­
t o r s o il m oisture, s o il temperatures and c lim a to lo g ic a l v a ria b le s .
LOCATION AND SOIL PROPERTIES
i'
The s ite selected f o r the experiment is on the Montana State
U n iv e rs ity F ie ld Research Laboratory farm located s ix m iles west o f
Bozeman, Montana, on U. S. Highway 191.
The s o il is an Amsterdam s i l t y
c la y loam w ith an approximate slope o f 1-2% in a n o rth e rly d ire c tio n .
The c h a ra c te ris tic s o f the s o il are given in Table I , p. 17.
DISPOSITION OF PLOTS AND TREATMENTS
The two crops grown were a lf a lf a and spring wheat in p lo ts
measuring TO meters by 10 meters.
Three d iffe r e n t ir r ig a t io n t r e a t ­
ments were applied to the a lf a lf a p lo ts w ith three re p lic a tio n s o f each
tre a tm e n t, re s u ltin g in nine p lo ts o f a lf a lf a .
The sp rin g wheat p lo ts
received fiv e d iffe r e n t tre atm e nts, three re p lic a tio n s per treatm ent,
fo r a to ta l o f f if t e e n p lo ts .
The treatm ents f o r the sp rin g wheat and
a lf a lf a are summarized in Table 2, p. 18.
These p lo ts were la id out
17
Table I
Water Holding P roperties and Bulk D ensities o f
Amsterdam S ilt y Clay Loam a t Research S ite
Depth,
cm.
r
F ie ld
C apacity, %
W iltin g
P o in t, I
Bul k
Density
30
22.9
11.7
1.27
60
22.4
10.4
1.25
90
22.4
9.2
1.24
120
24.0
12.4
1 .27
150
23.0
12.2
1 .24
180
21.4
10.0
1.24
210
19.0
8.5
1 .24
18
Table 2
D e scrip tion o f I r r ig a tio n Treatments
Crop
A lfa lfa
Spring Wheat
( I ) F all
( I ) Fall
(2) A fte r each c u ttin g
(2) F all + boot stage
(3) F a ll + sp rin g preseason
+ a ft e r each c u ttin g
(3) Boot stage
(4) J o in t stage + boot
stage
I
(5) F a ll + j o i n t stage +
boot stage
19
adjacent to each o th e r on the s ite i n 1blocks o f three p lo ts by fiv e
p lo ts fo r the sp rin g wheat and three p lo ts .by three p lo ts fo r the
a lf a lf a w ith two-meter lanes between the p lo ts and a fo u r-m e te r lane
between the a lf a lf a and sprin g wheat blocks.
a schematic o f the la y o u t.
See Figure I , p. 20, fo r
The p lo ts were randomized according to
treatm ents but the sprin g wheat p lo ts were la t e r derandomized to some
e xte n t due to te ch n ica l problems to be explained la t e r .
■IRRIGATION SYSTEM
i'
The p lo ts were ir r ig a te d in d iv id u a lly a t d iffe r e n t times during
the season according to the tre atm e nt.
Due to the randomized nature o f
the p lo ts , i t was necessary to design a s p rin k le r ir r ig a t io n system
which would ir r ig a t e any p lo t a t any time w ith o u t a ffe c tin g adjacent
p lo ts which were not to be ir r ig a te d .
This was accomplished by la y in g
tw o-inch diameter la te r a ls down each lane o f the a lf a lf a and spring
wheat p lo ts from a fo u r-in c h main Tine which was s itu a te d in the fo u rmeter lane between the crops.
Couplers were placed along the tw o-inch
la te r a ls so th a t each coupler would serve two corners o f adjacent
p lo ts , except a t each end o f the b lo c k , where one corner was served by
each coupler
(See Figure 2, p. 21.)
The couplers which served two
corners were f i t t e d w ith a T-arrangement so th a t two q u a rte r-c irc le
s p r in k le r heads could be u tiliz e d from each co u p le r, w ith one head
ir r ig a t in g each p lo t.
The heads were attached to the Tee by a q u ic k -
TREATMENT
PLOT
K - 2 M.
NUMBER
NUMBER
THERMOCOUPLE NUM BER
IO M.
rent
5
4
9
12
Tcism
3
3
8
13
TCHUE
2
5
7
TC 9&/0
14
ALFALFA
SPRING
Figure I .
Schena o f research p lo ts
WHEAT
PO
O
4 INCH ALUMINUM PIPE
2 INCH ALUMINUM PIPE
DOUBLE VALVE RISER
SINGLE VALVE RISER
Figure 2.
Research ir r ig a t io n system.
22
couple valve and key combination in order to be able to s e le c tiv e ly
in s e r t s p r in k le r heads in the pressurized lin e in none, one o r two
o f the valves a t each co u p le r, according to the ir r ig a t io n treatm ents.
See Figures 3 and 4, p. 23.
Each p lo t was thus ir r ig a te d by fo u r
q u a r te r - c ir c le s p rin k le rs o p era ting from each corner o f the p lo t.
Figure 5, p. 24.
See
Commercially a v a ila b le R ainbird 25PJDA s p rin k le r
heads w ith a s in g le nozzle 1/8" in diameter were used a t a pressure o f
40 p s i.
They came equipped w ith splash guards to reduce spray outside
o f the desired area.
INSTRUMENTATION
S o il M oisture Measurement
To m onitor s o il m oisture throughout the season as w ell as during
..1
the off-season w ith a neutron m oisture meter, a T ro x le r 2651 Scaler-Rate
Meter and 104A probe w ith Am/Be source, aluminum tubes were in s ta lle d
in the cen ter o f each p lo t to a depth o f 180 cm. in the sprin g wheat
and 210 cm. in the a lf a lf a .
The m oisture was measured a t depths o f
22.5, 45, 75, 105, 135 and 165 cm. in the spring wheat and a t an a d d i­
tio n a l increment o f 195 cm. in the a lf a lf a .
The m oisture was measured
before and a f t e r each ir r ig a t io n on the p lo ts to be ir r ig a te d , a t
re g u la r in te rv a ls throughout the season on a ll p lo ts and a t monthly
in te rv a ls during the off-season on a ll p lo ts .
Only two o f three r e p lic a ­
tio n s were m onitored during the off-season on the sp rin g wheat p lo ts .
23
Figure 3.
Two-inch coupler w ith double valve r is e r .
Figure 4. Two-inch coupler and double valve r is e r w ith keys and
s p rin k le r heads in s e rte d .
Figure 5.
Ir r ig a tio n system in operation.
25
S oil Temperature Measurement
___
D a ily maximum and minimum s o il temperatures were recorded a t
depths o f 5 and 20 cm. using a Leeds and Northrup Speedomax W 2 4 -p o in t
copper-constantan thermocouple re cord er.
Because o f instrum ent l im it a ­
tio n s , s o il temperatures were observed on only I o f 3 re p lic a tio n s fo r
each tre atm e nt.
The data was compiled on a weekly basis.
C lim a to lo g ica l V ariable Measurement
C lim a to lo g ica l data was compiled monthly from records obtained
from the Bozeman 6W weather s ta tio n approxim ately 1/2 m ile west o f the
research s it e .
These data included d a ily maximum and minimum a ir tem­
p e ra tu re s, p r e c ip ita tio n , d a ily incoming s o la r ra d ia tio n , d a ily wind
ru n, r e la tiv e hum idity and evaporation from a standard pan.
Y ie ld Measurement
'
Spring wheat y ie ld s fo r the 1977 season were obtained w ith a
small p lo t combine w ith a 4.5 f t . header.
One pass was made through
each p lo t from one side to the o th e r s id e .
The sample was c o lle c te d
and tagged a ft e r each pass through a p lo t.
The length o f the pass was
then measured.
By weighing each sample and knowing the area harvested,
the y ie ld fo r each p lo t was c a lc u la te d .
Chapter 3
RESULTS.
During the 1977 growing season, the ir r ig a t io n system was not
y e t completed a t the time o f the required ir r ig a t io n treatm ents on the
sp rin g wheat.
The sp rin g wheat was w ell past the f i r s t j o i n t stage and
e n te rin g the boot stage so i t was decided to ir r ig a t e a l l p lo ts re q u ir­
ing e ith e r o r both o f these treatm ents w ith the farm ir r ig a t io n system.
Since th is included a ll treatm ents except treatm ent I ( f a l l ir r ig a t io n )
and the system was not capable o f s e le c tiv e ly ir r ig a t in g p lo ts , tr e a tr
'
ment I p lo ts were derandomized and grouped a t the north end o f the
sprin g wheat blo ck.
This also derandomized some o f the o th e r p lo ts but
did a llo w ir r ig a t io n o f treatm ents 2-5.
Tables 3 and 4, pp. 27 and 28,
summarize the c u ltu ra l p ra c tic e s on the a lf a lf a and sp rin g wheat during
,
the 1977-78 season.
Tables 5 and 6 on pages 29 and 30 summarize the
dates and events o f s o il m oisture readings during the 1977-78 season.
YIELD VS. WATER APPLIED RELATIONSHIPS
—1977 SEASON
Since the sp rin g wheat was not ir r ig a te d a t the s p e c ifie d stages
o f growth, the o n ly re la tio n s h ip which can be in v e s tig a te d is the c o r­
re la tio n between y ie ld and to ta l amount o f water a p p lie d during the 1977
season.
The amount ap p lie d va rie d from 7.32 cm. on p lo t 9 to 18.92 cm.
on p lo t 13.
See Table 7, p. 31.
The v a ria tio n was due to edge e ffe c ts
27
Table .3
C u ltu ra l P ractices on Spring Wheat
-1 9 7 7 -7 8 Season
A p ril 25, 1977
P lots were seeded w ith 50 Ib ./A . Norana semi­
dwarf sp rin g wheat, no f e r t i l i z e r .
June 29 and 30, 1977
Treatments 4 and 5 were p a r t ia lIy ir r ig a te d
w ith a temporary system. A pproxim a tely.5 cm.
water was a p p lie d . .
Ju ly 5 and 6, 1977
Treatments 2-5 were ir r ig a te d w ith farm system.
September 9, 1977
I’
November 8, 1977
A ll p lo ts were harvested.
. gathered.
Y ie ld samples were
A ll p lo ts re q u irin g f a l l ir r ig a t io n were '
ir r ig a te d w ith approxim ately 3 cm. w ater.
28
T a b le .4
\
C u ltu ra l P ractices on A lfa lfa
--1977-78 Season
A p ril 19, 1977
A ll p lo ts were top-dressed w ith 200 Ib ./A . o f
0-45-0 f e r t i l iz e r.
May 2, 1977
P lots were seeded w ith 12-15 Ib ./A . Ladak-65.
Ju ly 5 and 6, 1977
A ll p lo ts were ir r ig a te d w ith farm system.
August 9, 1977
Al I p lo ts were harvested.
taken.
November 9, 1977
i’
Treatments I and 3 were ir r ig a te d w ith a p pro ximately 3 cm. w ater.
No y ie ld data was
29
Table 5
Log o f S oil M oisture Readings on Spring Wheat
—1977-78 Season
Gregorian
Date
r
J u lia n
Date
Event
6-21-77
7172
I n i t i a l reading
7-1-77
7182
. P o s t- ir r ig a tio n
7-5-77
7186
P r e - ir r ig a tio n
7-7-77
7188
P o s t-ir r ig a tio n
7-8-77
7189
P o s t- ir r ig a tio n
8-2-77
7214
Check
10-20-77
7293
P r e - ir r ig a tio n
11-14-77
7318
P o s t- ir r ig a tio n
12-29-77
7363
Check
1-23-78
8023
Check
2-22-78
8053
Check
3-30-78
8089
Check
30
Table 6
Log o f S oil M oisture Readings on A lfa lfa
- - 1 977-78 Season
Gregorian
Date
J u lian
Date
Event
7-7-77
7188
I n i t i a l reading
Post - i r r ig a tio n
8-2-77
7214
Check
10-28-77
7301
P re - ir r i gation
11-14-77
7318
P o s t- ir r ig a tio n
12-29-77
7363
Check
1-23-78
8023
Check
2-22-78
8053
Check
3-30-78
8089
Check
31
Table 7
Amount o f Water Applied to Spring Wheat,
cm.--1977 Season
J u lian Date
P lo t
Number
7172
1
7179
—
7182
7186
7188
—
7189
—
0
2
44.92
3
46.08
—
—
40.83*
—
54.11
13.28
4
46.13
—
—
40.88*
—
56.09
15.21
5
49.47
--
—
44.22*
—
52.64
8.42
6
44.94
—
--
39.69*
—
48.68
9.99
7
46.42
—
—
41.17*
—
52.82
11.65
8
45.82
—
—
40.55
57.72
45.11*
52.43
9
—
39.66
—
46.61
49.40
Applied
Water, cm.
9.74
—
17.17
7.32
0
10
11
41.92*
0
;;
9.87
—
59.09
18.92
41.08*
—
56.98
15.90
39.49
—
46.78
7.29
—
51.79
46.01
12
43.94
13
45.42
—
—
40.17*
14
46.33
—
—
15
44.72
—
—
♦Estimated from e v a p o tra n s p ira tio n rates o f P lots 2, 8 and 15
from 7172 to 7186. ETo = (44.92 - 39.66)/14 days = 0.376 cm./day;
ET8 = (45.82 - 40.55)/T4 days = 0.376 cm ./day; ET15 = (44.72 39.49)/14 days = 0.374 cm./day.
32
o f the s p r in k le r d is tr ib u tio n p a tte rn o f the farm system.
Graphing
to ta l ap p lie d water vs. y ie ld (see Table 8, p. 33) showed considerable
s c a tte r in the data.
See Figure 6, p. 35.
ment is given in Table 9, p. 34.
The average y ie ld by t r e a t ­
A second order regression c o rre la tio n
(Lund, Smith E .), e lim in a tin g one data p o in t from p lo t 5 because the
p o in t was not re p re se n ta tive o f the tre a tm e n t, y ie ld e d an equation which
in d ic a te s th a t y ie ld increases w ith in cre asing water up to a p o in t, then
2
The equation, Y = 50.15 + 1.397x - 0.0507x , gives a maximum
decreases.
a t x = 13.78 cm .,
Y = 59.77 q./H a.
A value o f r
?
= 0.7804 was computed
fo r th is re gre ssio n.
Y ie ld data fo r the a lf a lf a was not taken from the one c u ttin g
during the 1977 season because the stand was in the process o f becoming
e s ta b lis h e d .
■ 1.
.J
CONDITIONS OF FALL IRRIGATION
.
.
On November 8, 1977, the bare p lo ts re q u irin g f a l l ir r ig a t io n
which were to be seeded to sprin g wheat the fo llo w in g sp rin g were
ir r ig a te d w ith approxim ately 3 cm. w ater.
The amount ap plied was not
the same on each p lo t because o f system d i f f i c u l t i e s and fre e z in g o f
s p r in k le r heads.
ir r ig a t io n
w ater.
On November 9, 1977, the a lf a lf a p lo ts re q u irin g f a l l ■
(treatm ents I and 3) were ir r ig a te d w ith approxim ately 3 cm.
33
Table 8
Spring Wheat Y ie ld D a ta --I977 Season
P lo t Number/
Treatment No.
Sample
Net W t., lb .
1/1
15.28
2/2
Y ie ld *
Bu./A.
Y ield
q./H a.
3.36
75.85
51.06
16.59
3.36
82.35
55.43
3/4
17.94
3.36
89.06
59.95
4/3
16.81
3.36
83.45
56.17
5/5
13.23
3.41
64.68
43.54
6/4
17.59
3.25
90.09
60.64
7/2
17.21
3.31
86.77
58.41
8/3
17.94
3.36
89.06
59.95
9/5
17.09
3.36
84.84
57.11
10/1
14.73
3.31
74.26
49.99
11/1
14.31
3.31
72.15
48.57
12/4
18.38
3.36
91.24
61.42
13/3
18.28
3.41
89.37
60.16
14/5
17.71
3.36
87.91
59.17
15/2
18.54
3.41
90.64
61.01
♦Assume 60 Ib ./B u .
Sample Area
x IO3, A.
34
Table 9
Average Spring Wheat Y ie ld by Treatment
--1977 Season
I *
Treatment
P lots
Bu./A.
q./H a.
I
1-10-11
74.09
49.87
2
2-7-15
86.59
58.28
3
4-8-13
87.29
58.75
4
3-6-12
90.13
60.67
5
5-9-14
79.14
53.27
35
0.0507%
0.7804
Applied w a te r, cm.
Figure 6.
Y ie ld vs. applied water c o r re la tio n , sprin g wheat 1977.
36
MIGRATION OF SOIL WATER OVER-WINTER
Throughout th e -w in te r, monthly s o il m oisture readings were taken
on two o f three re p lic a tio n s o f a l l treatm ents in the sp rin g wheat p lo ts
and on a l l a lf a lf a p lo ts .
From these readings, the to ta l centim eters
o f w ater in each 30 cm. s o il p r o f ile in te rv a l were computed fo r each
date on which readings were taken.
appendix.
This data is summarized in the
A fa m ily o f graphs fo r each p lo t monitored o v e r-w in te r was
constructed showing the movement o f s o il water fo r each successive
s o il m oisture reading.
show anincrease
See Figure 7, pp. 37-41.
in s o il m oisture in
and losses in the 0-90 cm. zones
In general, the graphs
the 90-150 cm. zones, mixed gains
and r e la tiv e ly l i t t l e
change in the
zones from 150-210 cm.
GAIN OR LOSS OF SOIL WATER OVER-WINTER
From the data summary, the ir r ig a te d spring wheat p lo ts showed
no d is c e rn ib le tendency to gain o r lose m oisture o v e r-w in te r from
December 29, 1977, to February 22, 1973.
Three p lo ts gained from 0.1 0-
0.65 cm.
w ith an average o f 0.32
cm. w h ile three p lo ts lo s t from 0.14-
0.59 cm.
w ith an average o f 0.39
cm. Of the fo u r n o n -irrig a te d p lo ts ,
three gained from 0.42-0.94 cm. w ith an average o f 0.65 cm. w hile one
p lo t lo s t 2.63 cm.
During the same p e rio d , the s ix f a l l - i r r i g a t e d a lf a lf a p lo ts
gained 1.15 to 2.57 cm. o v e r-w in te r w ith an average o f 2.10 cm.
The
37
Water co n te n t, cn.
Water co n te n t, cm.
4
5
P r o file depth, cn.
2
8
10
o Ja n .23,1978
Feb.22,1978
a
2 159-
P lo t 3
P lo t I
Water co n te n t, cm.
Water c o n te n t, cm.
2
4
6
8
2
10
4
6
8
P r o file depth, cn.
30B
60
S. 90
CU
Tl
OJ 120
t
150130-
P lo t 4
Finure 7.
210J
P lo t 5
D is p o s itio n o f m oisture in s o il p r o file s o v e r-w in te r.
10
38
Hater c o n te n t, cm.
Hater c o n te n t, cm.
4
6
3
10
2
4
6
8
10
P r o file depth, cm.
2
P lo t 9
Water co n te n t, cm.
Water c o n te n t, cm.
4
6
8
10
2
4
6
8
P r o file depth, cm.
2
P lo t 7
P lo t 11
Figure 7.
(C ontinued).
P lo t 12
10
39
Water c o n te n t, cm.
P r o file depth, cm.
Water c o n te n t, cm.
90<u 120-
P lo t 13
P r o file depth, cm.
2
Water co n te n t, cm.
4
6
3
Water c o n te n t, cm.
10
w 1202- 150-
P lo t IA
Figure 7.
P lo t 15
(C ontinued.)
P lo t 2A
40
P r o file depth, cm.
2
Water co n te n t, cm.
4
6
8
10
2
^
Water co n te n t, cm.
4
5
8
120-
P lo t 4A
P lo t 3A
Water c o n te n t, cm.
Water co n te n t, cm.
P r o file depth, cm.
□ WftA
w 120£
P lo t 5A
Figure 7.
(C ontinued.)
150-
P lo t 6A
10
41
Water c o n te n t, cm.
P r o file depth, cm.
Water co n te n t, cm.
P lo t 7A
P lo t 8A
Water co n te n t, cm.
P r o file depth, cm.
i
P lo t 9A
Figure 7.
(C on tinu ed.)
42
three n o n -irrig a te d p lo ts gained.from 1.63 to 2.98 cm. w ith an average
o f 2.16 cm.
Water Storage in Spring Wheat
E ffe c tiv e p r e c ip ita tio n e n te rin g p r o f i l e .
To determine the pe r­
centage o f o v e r-w in te r p r e c ip ita tio n which entered the s o il p r o f ile ,
treatm ents which received no f a l l ir r ig a t io n were evaluated.
in m oisture in the p r o f ile is due s o le ly to p r e c ip ita tio n .
Any gain
For the
sprin g wheat treatm ents 3 and 4, p lo ts .4, 13, 3 and 12 were monitored
o v e r-w in te r from December 29, 1977, to March 30, 1978.
The p r e c ip ita ­
tio n during th is period was 6 .2 .cm. as summarized in Table 10, p. 43.
These p lo ts gained, re s p e c tiv e ly , 1 .6 , 6 .5 , 2.7 and 2.9 cm. water during
th is p e riod .
The gain r a tio s , the r a tio o f amount gained to p r e c ip ita ­
tio n , are 0.25, 1.05, 0.44 and 0.4 7, re s p e c tiv e ly .
The variances and
the r a tio over 1.0 are probably due to d iffe re n c e s in snow d r if t s on
the p lo ts .
The average o f these fo u r ra tio s is 0.55. . Applying th is
r a tio to the period from November 14, 1977, to March 30, 1978, in which
10.29 cm. o f p r e c ip ita tio n was re ceived , the e ffe c tiv e p r e c ip ita tio n
stored by the s o il is 5.66 cm.
B ut, adding th is amount to the s o il
m oisture recorded on November 14, 1977, g ive s, in a l l cases, an amount
less than th a t recorded on March 30, 1978.
This means th a t some o f the
w ater in the p r o f ile is excess and is unaccounted fo r .
The maximum
amount th a t can have entered is assumed to be 10.29 cm., the amount o f
43
Table 10
P re c ip ita tio n Summary
— Bozeman 6W S ta tio n
Date
Inches
11/14/7712/29/77
1.61
4.09
12/29/771/23/78
0.61
1.55
r — CM
CO CM
CM CM
CO CO
r>*
0.89
2.26
CM CO
CM O
CM CO
I
CO CO
r-x
0.94
2.39
4.05
10.29
Total
Centimeters
44
p r e c ip ita tio n during the p e rio d .
The minimum amount is the d iffe re n c e
between the s o il m oisture le v e ls on November 14, 1977, and March 30,
1978.
The average d iffe re n c e f o r a ll sp rin g wheat p lo ts which were f a l l
ir r ig a te d is 7.15 cm.
This was averaged w ith the maximum, 10.29 cm., •
fo r a value o f 8.72 cm. which entered the p r o f ile .
This gives a gain
r a tio o f 0.85.
Storage e ff ic ie n c y .
The e ffic ie n c y o f storage was then c a l­
cu la te d , assuming th a t 8.72 cm. o f the to ta l p r e c ip ita tio n entered the
s o il p r o f ile .
The e ffic ie n c y was c a lc u la te d by ta k in g the sum o f the
to ta l m oisture le v e l on November 14, 1977, in ce n tim e te rs, and the
e ffe c tiv e p r e c ip ita tio n , then s u b tra c tin g the. to ta l m oisture le v e l on
March 30, 1978, in centim ete rs.
lo s t o v e r-w in te r.
This gives the to ta l amount o f water
The e ffic ie n c y is thus the amount o f water applied
minus th a t lo s t d ivid e d by the amount o f water applied times 100.
Treatment I , p lo ts I and 11, y ie ld e d e ffic ie n c ie s o f 63 and 65%,
re s p e c tiv e ly .
P lots 7 and 15 o f treatm ent 2 gave e ff ic ie n c ie s , respec­
t iv e ly , o f -217 and 105%.
This s ig n ifie s th a t p lo t 7 lo s t more water
than was applied to i t by ir r ig a t io n and th a t p lo t 15 gained more water
than was applied to i t .
The e ffic ie n c ie s o f treatm ent 5, p lo ts 5 and
9, were 43 and 105%, re s p e c tiv e ly .
than was a p p lie d .
Again, p lo t 9 gained more water .
The c a lc u la tio n s are summarized in Table 11, p. 45.
45
Table 11
Water Storage E ffic ie n c y in Spring Wheat
Treatment
I
P lo t Number
2
I
11
5
7
15
5
9
Cm. water applied on
11/8/77
3.72
3.51
1 .86
2.75
2.39
3.70
Total cm. water/180
cm. depth on 11/14/77
35.33
36.09
43.42
38.32
43.11
41.35
8.72
8.72
8.72
8.72
8.72
8.72
Total cm. water
applied
44.05
44.81
52.14
47.04
51.83
50.07
Total cm. water/180
cm. depth on
3/30/78
42.66
43.58
46.25
47.18
50.46
50.37
1.39
1.23
5.89
-0.14
1.37
-0 .20
E ffe c tiv e p re cip .
from T l/1 4 /7 7 to
3/30/78
Total cm. water lo s t
o v e r-w in te r
E ffic ie n c y , %
63
65
-217
105
43
105
46
Water Storage in A lfa lfa
E ffe c tiv e p r e c ip ita tio n e n te rin g p r o f i l e .
The e ffic ie n c y o f
storage, in a lf a lf a was c a lc u la te d in the same manner as the spring
wheat.
To account f o r p r e c ip ita tio n e n te rin g the p r o f ile , the gain
r a tio was c a lc u la te d by determ ining the amount o f w ater stored over­
w in te r in n o n -fa ll ir r ig a te d p lo ts .
The r a tio fo r p lo ts 3A, 6A and
8A o f treatm ent 2 were 1.2 4 ,.1 .08 and 0.82, re s p e c tiv e ly .
o f these three ra tio s is 1.05.
0.95.
The average
An average o f the two low er ra tio s is
Since th is s t i l l seems h ig h , a value o f 0.90 was assumed.
The
e ffe c tiv e p r e c ip ita tio n fo r the period November 14, 1977, to March 30,
1978, is thus 0.90 x 10.29, o r 9.26 cm.
Storage e ff ic ie n c y .
The e ffic ie n c ie s as computed in Table 12,
.I
p. 47, were a ll n e gative , w ith one exception. P lo t 4A o f treatm ent
I had a 25% e ffic ie n c y .
The negative e ffic ie n c ie s in d ic a te d th a t more
w ater was lo s t from the p r o f ile o v e r-w in te r than was applied in f a l l
ir r ig a t io n .
The p lo ts d id however e x h ib it a gross gain in m oisture.
A d d itio n a l Data from South Dakota
South Dakota State U n iv e rs ity a t Brookings, South Dakota, is
perform ing the same experiment w ith a lf a lf a and sp rin g wheat, as w ell
as corn and w in te r wheat.
As a means o f comparison, o v e r-w in te r s o il
m oisture data (C arlson, 1978) f o r the a lf a lf a and sp rin g wheat p lo ts
47
Table 12
Water Storage E ffic ie n c y in A lfa lfa
Treatment
I
3
P lo t Number
2A
4A
7A
Cm. water applied
on 11/9/77
4.38
6.05
2.38 '
46.21
46.38
43.17
9.26
9.26
Total cm. water
applied
55.47
Total cm. w ate r/
210 cm. depth on
3/30/78
Total cm. water
lo s t o v e r-w in te r
Total cm. w a te r/
210 cm. depth on
11/14/77
I
E ffe c tiv e p re c ip .
from 11/14/77 to
3/30/78
E ffic ie n c y , %
5A
9A
3.47
3.41
44.66
45.07
43.04
9.26
9.26
9.26
9.26
55.64
52.43
53.92
54.33
52.30
50.90
51.11
48.07
48.55
49.70
47.60
4.57
4.53
4.36
5.37
4.63
4.70
-4
25
-83
IA
3.49
-54
-33
-38
'48
were evaluated.
The treatm ent numbers are the same as they are f o r the
Montana experiment.
E ffic ie n c y in sp rin g wheat.
three sp rin g wheat p lo ts y ie ld s an
An e va luatio n o f the gain r a tio fo r
average o f 0.44.
The p r e c ip ita tio n
during the o v e r-w in te r period from October 26, 1976, to A p ril 7, 1977,
was 22.78 cm.
The e ffe c tiv e p r e c ip ita tio n is thus 9.99 cm.
Treatments
I and 2 received 15.24 cm. o f fa ll- a p p lie d water w h ile treatm ent 5
received 25.24 cm.
P lots 59 and 66 o f treatm ent I were each 57% e f f i ­
c ie n t, in s to rin g f a l l ir r ig a t io n .
e f f ic ie n t .
P lo t 61 o f treatm ent 2 was 55%
P lots 51, 53 and 55 o f treatm ent 5 were, re s p e c tiv e ly , 73,
75 and 71% e f f ic ie n t .
E ffic ie n c y in a l f a l f a .
The average gain r a tio f o r s ix n o n -fa ll
ir r ig a te d a lf a lf a p lo ts was 1.07.
The minimum gain r a tio was 0.79.
It
was assumed th a t the gain r a tio was less than 1.0 but g re a te r than 0.79.
The gain r a tio assumed was 0.90. ' The e ffe c tiv e p r e c ip ita tio n was then
0.90 x 22.78 cm. o r 20.50 cm.
25% fo r p lo ts 69, 73 and.76.
Treatment I e ffic ie n c ie s were 19, 29 and
P lots 68, 74 and 75 o f treatm ent 3 were
42, 13 and 43% e f f ic ie n t .
- / ■.
WATER STORAGE EFFICIENCIES VS.
PERCENT FIELD. CAPACITY
In an attem pt to determine a t what m oisture content f a l l i r r i g a ­
tio n becomes fe a s ib le ,. the e ffic ie n c y o f storage o f each p lo t vs. the
49
percent f i e l d cap acity p r io r to ir r ig a t io n were graphed.
See Figure 8.
The to ta l f i e l d ca p a city to 180 cm. depth is 40.83 cm. in the spring
wheat and 46.53 cm. to 210 cm. depth in the a lf a lf a .
The m oisture con­
te n t o f the s o il in the f a l l p r io r to ir r ig a t io n should be an in d ic a to r
o f whether to ir r ig a t e o r n o t.
A considerable s c a tte r in the po ints is
evid ent and no good c o rre la tio n was e sta b lish e d .
RELIABILITY OF DATA
*
"W
/
The s o il m oisture readings were found to be 3-10% higher than
i'
correspondent g ra v im e tric samples when using the m anufacturer's c a l i ­
b ra tio n ta b le s .
Therefore, numerous g ra v im e tric samples were c o lle c te d
a t d iffe r e n t m oisture content le v e ls w h ile readings were taken w ith
the neutron meter.
The m oisture content was then c a lc u la te d using the
neutron meter m anufacturer's ta b le s and also from the g ra v im e tric
samples.
These two values were I i n e a rly c o rre la te d so th a t a c o rre c tio n
o f the in s tru m e n t's readings could be made.
The values obtained through
th is process were good to e x c e lle n t, but i t was necessary to recheck the
c o rre la tio n w ith new f i e l d data re g u la rly to a s c e rta in th a t the c o rre la ­
tio n was s t i l l v a lid .
This was a problem throughout the p ro je c t and
continues to be so, despite re c a lib ra tio n o f the instrum ent by the /
m anufacturer.
For some s t i l l undetermined reason, the c a lib r a tio n
tab les supplied w ith the instrum ent are not v a lid f o r the s o il o f th is
experim ent. .
50
Percent o f f ie ld c a p a c ity , p r io r to ir r ig a t io n
Figure 8. Water storage e ffic ie n c ie s vs. percent f i e l d cap acity p r io r
to ir r ig a t io n .
51
The amount o f water applied in the f a l l was very v a ria b le be­
tween p lo ts .
tio n .
The amount was also s m a ll, due to lim ite d time o f i r r i g a ­
The small amount applied needs to be measured more accu ra te ly
since small e rro rs in measurement w i l l cause large e rro rs in e ffic ie n c y
c a lc u la tio n s .
The ca lcu la te d e ffic ie n c ie s a t best give an idea o f the
magnitude o f e ffic ie n c ie s and g e n e ra lly show the e ffe c ts o f a dry pro­
f i l e vs. a w e tte r p r o f ile .
The e ffic ie n c y c a lc u la tio n s were also com plicated by the uncer­
ta in ty o f how much o f the o v e r-w in te r p r e c ip ita tio n a c tu a lly entered
I *
the p r o f ile .
Snow depths and d r if t s need to be monitored more c lo s e ly
to take these e ffe c ts in to co n sid e ra tio n in e ffic ie n c y , c a lc u la tio n s .
South Dakota applied 15-25 cm. water in the f a l l w h ile Montana
applied only 3 cm.
This makes a d iffe re n c e in c a lc u la tio n s .
A small
e rro r in measurement w i l l cause a la rg e r e r ro r in the Montana data than
in the South Dakota data.
Chapter 4
CONCLUSIONS
From the eva lu a tio n o f the data, there are some general
re la tio n s h ip s which can be in fe rre d w ith respect to y ie ld vs. applied
w ater, water storage e ffic ie n c y and storage e ffic ie n c ie s vs. percent
o f f i e l d ca p a c ity .
Because o f a lack o f data and some inaccurate data,
precise re la tio n s h ip s are d i f f i c u l t to o b ta in .
YIELD VS. WATER APPLIED
I'
A good general re la tio n s h ip between amount o f water applied and
y ie ld f o r the 1977 season was obtained.
The second order c o rre la tio n
did show a d e fin ite peak in y ie ld a ft e r which an increase in water
decreased y ie ld s .
This is to be expected, since common sense t e l l s one
th a t y ie ld w i l l not increase in d e f in it e ly w ith in cre asing w ater.
WATER STORAGE EFFICIENCIES
I t appears th a t a p a rt o f the fa ll- a p p lie d w ater can be stored
o v e r-w in te r, i f the s o il p r o f ile is dry enough p r io r to f a l l ir r ig a t io n
P ro file s which were w e tte r did not have as high e ffic ie n c ie s as the
d r ie r p r o file s d id .
This is because the d r ie r p r o file s have more s to r ­
age room than the w e tte r p r o file s .
Water applied to wet p r o file s has
no place to be stored and thus is flushed through the p r o f ile and is
lo s t to deep drainage.
I t is not c le a r y e t what the maximum s o il
53
m oisture le v e l should be before f a l l ir r ig a t io n is not fe a s ib le .
The South Dakota data y ie ld e d s im ila r re s u lts .
T h eir data,,
however, was more c o n s is te n t and the e ffic ie n c ie s c a lc u la te d were more
uniform w ith in treatm ents.
A gain, the d r ie r p r o file s had higher e f f i ­
cien cie s than the wet p r o file s .
WATER STORAGE EFFICIENCIES VS.
PERCENT FIELD CAPACITY
Upon p lo ttin g e ffic ie n c y vs. percent f i e l d ca p a c ity before f a l l
ir r ig a t io n , a considerable s c a tte r in the data is e v id e n t.
P o s itiv e
e ffic ie n c ie s were found in p r o file s which were a t 100% o f f ie ld
cap acity and negative e ffic ie n c ie s were found in p r o file s which were
a t 85% o f f i e l d ca p a c ity .
The a lf a lf a p lo ts a ll showed a negative
e ffic ie n c y w ith one exception.
This is to be expected because the
s o il p r o file s were g e n e ra lly w e tte r in the a lf a lf a than in the sprin g
wheat.
A general trend th a t may be observed is th a t the e ffic ie n c e s
tend to get more p o s itiv e w ith d r ie r s o il p r o f ile s .
This trend would
have to be v e r ifie d by more accurate and extensive data.
' tv*
Chapter 5
SUMMARY
The d is p o s itio n o f l a t e - f a l l applied ir r ig a t io n w ater in the
s o il p r o f ile o v e r-w in te r was in v e s tig a te d .
This was to determine the
e ffe ctive n e ss and f e a s i b i l i t y o f l a t e - f a l l ir r ig a t io n .
The amount o f
w ater w ith in the s o il p r o f ile was monitored monthly during the w in te r
season on a lf a lf a and sp rin g wheat p lo ts a t incremental depths o f 30 cm
to a depth o f 180 cm. in the sp rin g wheat and 210 cm. in the a lf a lf a
to determine the movement o f water in the p r o f ile and the e ffic ie n c y
I ’ ‘
o f storage o f fa ll- a p p lie d w ater during the period .
.
. PROCEDURES
The p lo ts were ir r ig a te d in e a rly November w ith approxim ately
3 cm. o f w ater by a s p r in k le r system.
S o il m oisture was monitored
monthly on a ll p lo t s , f a l l ir r ig a te d and n o n -fa ll ir r ig a t e d , by the
neutron a tte n u a tio n method.
D a ily maximum and minimum s o il tempera­
tures a t 5 and 20 cm. depth and m eteorological data were also recorded
but not analyzed in th is paper.
YIELD VS. APPLIED WATER
Spring wheat y ie ld data from the 1977 season was c o rre la te d
w ith to ta l amount o f water a p p lie d .
A good c o rre la tio n ( r
was obtained w ith a second order regression e v a lu a tio n .
2
= 0.7804)
I t shows th a t
55
y ie ld increases w ith’ increased ir r ig a t io n u n til a peak is reached, then
s ta r ts to d e c lin e .
DISPOSITION OF SOIL WATER OVER-WINTER .
Water movement in the p r o f ile o v e r-w in te r was g e n e ra lly the same
f o r a ll p lo ts .
The 90-150 cm. zones gained m oisture w h ile the 0-90 cm.
zones showed no d e fin ite trend to gain o r lose m oisture.
depths o f 180-210 cm. showed r e la t iv e ly l i t t l e
Water a t
movement, except in the
sp rin g when the p r o f ile was being f i l l e d by spring ru n o ff.
A lfa lfa
p lo ts , ir r ig a te d and n o n -irrig a te d , tended to have a gross gain in to ta l
w ater in the p r o f ile o v e r-w in te r, w h ile sprin g wheat p lo ts were about
even in the number o f p lo ts gaining o r lo s in g m oisture.
STORAGE EFFICIENCIES ■
/
'
;
E ffic ie n c ie s o f storage o f f a l l applied water va rie d w id e ly .
In
the sp rin g wheat, two treatm ent I p lo ts were 63 and 65% e f f ic ie n t w h ile
treatm ent 2 p lo ts were -217 and 105% e f f ic ie n t .
43 and 105% e f f ic ie n t .
Treatment 5 p lo ts were
Out o f s ix a lf a lf a p lo ts which were f a l l i r r i ­
gated, on ly one had p o s itiv e e ffic ie n c y , 25%.
The s o il p r o file s o f the
a lf a lf a were t y p ic a lly w e tte r in the f a l l than were the spring wheat
p r o file s .
Data from the same experiment in South Dakota (C arlson, 1978)
were also analyzed.
In the spring
wheat, two
treatm ent I p lo ts
56
both y ie ld e d e ffic ie n c ie s o f 57%.
e f f ic ie n t .
One p lo t in treatm ent 2 was 55%
Treatment 5 p lo ts were 73, 75 and 71% e f f ic ie n t .
a lf a lf a p lo ts showed a l i t t l e
were 19, 29 and 25% e f f ic ie n t .
more v a r ia b ilit y .
The
Treatment I p lo ts
E ffic ie n c ie s o f treatm ent 3 p lo ts were
42, 13 and 43%.
RECOMMENDATIONS FOR FURTHER RESEARCH
I t has been shown th a t a p o rtio n o f fa ll- a p p lie d ir r ig a t io n
water can be s u c c e s s fu lly stored o v e r-w in te r in the s o il p r o f ile .
i"
is not c le a r, though, a t what m oisture content f a l l ir r ig a t io n is
e f f ic ie n t .
It
This needs to be studied more thoroughly and w ith more
accurate data.
I t needs to be determined a t what percent o f f i e l d <
cap acity f a l l ir r ig a t io n becomes i n e f f ic ie n t , so th a t an i r r ig a t o r can
measure the s o il m oisture in the f a l l and decide i f f a l l ir r ig a t io n is
d e s ira b le .
Another problem encountered in the p ro je c t was the e ffe c t o f
o v e r-w in te r p r e c ip ita tio n on s o il w ater.
How is the e ffe c tiv e amount ■
o f p r e c ip ita tio n e n te rin g the p r o f ile best determined?
have an e ffe c t?
in f ilt r a t e s ?
Do sn o w d rifts
How much water runs o f f in the sp rin g and how much
These are questions which were d i f f i c u l t , i f not almost
im p o ssib le , to answer s a t is f a c t o r ily in the analysis o f the data in th is
paper.
57
CONCLUSIONS
From the regression analysis o f sprin g wheat y ie ld vs. water
a p p lie d , i t . is c le a r .th a t there is a p o in t where a d d itio n a l water w ill
cause no fu r th e r increase in y ie ld .
off-season ir r ig a t io n is b e n e fic ia l.
During a dry f a l l o r dry s p rin g ,
Heavy f a l l p r e c ip ita tio n o r i n f i l ­
tr a tio n from sp rin g ru n o ff w i l l tend to flu s h any ap plied water through
the p r o f ile , thus lo s in g i t to deep drainage.
From the data, i t is not
c le a r a t what maximum percentage o f f i e l d cap acity p r io r to f a l l i r r i ­
gation th a t f a l l ir r ig a t io n becomes in e f f ic ie n t .
In the range o f pe r­
centages encountered in th is study, from 75-100% o f f i e l d c a p a c ity ,
there was no d e fin ite p a tte rn .
I n t u i t i v e l y , i t would seem th a t a t
ranges o f 50-75% o f f i e l d c a p a c ity , higher e ffic ie n c ie s would be ob­
ta in e d .
This needs to be studied more thoroughly.
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PLOT NUMBER
I
3
J U L IA N DATE
J U L I A N DATE
7318
8023
7363
TOTAL MOISTURE CONTENT,
CP. *
AT
805 3
3 0 ,6 0 ,9 0 . ..C P
8 089
«05 3
P023
7363
TOTAL MOISTURE CONTENT,
DEPTH
CM .,
AT
5089
3 0 ,6 0 ,, 9 0 . ..CM
DEPTH
8 .4 5 00 0
8.75000
8.76000
9 .5 1 0 0 0
8.3 6 00 0
8 .8 2 03 0
8 .7 9 00 0
8.77000
7 .6 3 0 0 0
7.58000
7 .1 1 0 0 0
7.5 2 00 0
« .3 3 0 0 0
7.94000
7.66009
P .3 6 0 0 0
9.09030
* . OBOOO
4.88000
4 .7 6 0 0 0
4.5 3 00 0
7.53000
6.95000
6 .7 9 0 9 0
6.59000
8.18000
J . SJOOO
4.21000
4.46000
4 .7 4 00 0
5.11000
6.60000
6.50000
6 .5 4 00 0
6 .6 5 00 0
5 .2 3 0 0 0
5.4 7 03 0
5.38000
5.31000
5.51000
6 .6 0 00 3
6.75030
6.58000
6.54000
5.6 2 00 0
5.65000
AT IdOCN DEPTH
5.5 7 00 0
5 .6 5 0 0 0
6.66000
6.5 2 00 0
36.2400
36.4500
42.6600
43.2500
45.7800
9 .1 9 0 0 0
5 .6 5 0 0 0
total
cp
water
35.3300
PLOT NUMBER
36.1200
TOTAL00 *
43.1530
43.1200
PLCT NUMBER
4
DEPTH
WATER
5
J U L IA N DATE
JULIAN DATE
8053
8023
7363
TOTAL MOISTURE CONTENT, CM .,
7318
8089
7363
TOTAL POlSTURE
AT 3 0 , 6 0 , 9 0 . . .CM DEPTH
CONTENT,
«323
CP . •
8 053
AT 3 0 . 6 0 , , 9 0 . . . C P
80*9
CEPTH
7. 6 5 OCO
8. 23 00 0
8. 220 00
8. 0 4 0 0 0
8 .7 5 00 0
8.40000
9.38000
9 .2 8 00 0
8.80000
7. 74 00 0
7. 55 00 0
7. 450 00
8. 5 7 0 0 0
7 .0 5 00 0
7 .6 7 00 0
7.24000
6.87000
9 .3 3 0 0 0
7. 31 00 0
7. 0 5 0 0 0
6. 9 7 0 0 0
7. 9 7 0 0 0
6.02000
6.39000
6.37000
6 . 5 60 00
9 .2 8 0 0 0
7. 160 00
7. 140 00
7. 03 00 0
7.25000
6.69000
6 .930V 0
7
6 .7 9 00 0
7 .7 0 0 0 0
7 . Oj OOO
7. 090 00
6.92000
6.99000
7 . 4 6 CCO
7.38000
7.37000
7.22000
7.75000
7. 20 00 0
7. 1 8 0 0 0
6.99000
7.56000
43.B000
46.0200
44.6100
43.7600
50.4500
8023
« 053
eo«9
TOTAL0ES WATER i » m
PLCT
NUMBER
JULIAN
DEPTH
TOTAL0 0 " WATER
PLCT NUMBER
7
JUL IA N
7 36 3
MOISTURE CONTENT,
80 2 3
C M .,
8 05 3
8089
U f P T H 7 - L 3000
9
DATE
7 ?1 8
TOTAL MOISTURE
AT 3 0 , 6 0 , 9 0 . . I. CM DEPTH
I , '! ! # ,
43.9000
43.1100
DATE
731 8
TOTAL
.
44 .5 10 0
44 . 3 9 0 0
7363
CONTENT,
CM. ,
AT 3 0 , 6 0 , , 9 0 . . . C M
DEPTH
8 .2 1 0 0 0
7.93000
8 .3 2 00 0
8.21000
8.67000
9 .4 7 00 0
8.68000
9.54000
9 .3 5 0 0 0
9 .6 5 0 0 0
7 .9 7 0 0 0
7.87000
7.58000
7 .98 0 00
8.88000
8.9 2 00 0
8.4 8 00 0
9.17000
8 .1 1 00 0
9 .4 4000
8.33000
7.14000
7.20000
7
6.7 0 00 0
8.44000
5.48000
6.45000
6.50000
6.27000
6 .5 3 0 0 0
6.47000
6 .4 2 0 0 0
6.2 4 00 0
6 .9 0 0 0 0
5.30000
5 .5 8 00 0
5.74000
5 .6 0 00 0
7.63000
6 .6 2 0 0 0
6 .5 4 00 0
6.55000
6 .4 4 00 0
6 .4 5 0 0 0
5 .8 5 00 0
5 . PbOOO
6 .0 1 00 0
5 .9 2 00 0
7 .9 1000
. 6 .2 3 00 0
DEPTH
6 .0 3 00 0
7.36000
42.2200
41.2100
50.3600
6 .9 2000
TOTAL CP WATER
43.4200
DEPTH
42.9500
7 .0 4 00 0
6.7 8 00 0
6 .8 8 0 0 0
42.9400
42.3600
46.2500
TOTAL0CP WATER
41.3500
41.2139
Appendix. Summary o f O ver-w inter M oisture Levels in Spring I
A lf a lf a — 1977-78 Season.
PLOT NUMPER
CJ
rh
CU
ZJ
CL
Appendix.
PLOT NUMBER
11
J U L I A N OATF
J U L IA N DATE
731b
736 3
TOTAL MOISTURE CONTENT,
8 023
C M .,
805 3
AT 3 0 , 6 0 , 9 0 . . . C M
80P9
7363
8023
TOTAL MOISTURE CONTENT,
DEPTH
9.10000
8 .7 9 00 0
9 .0 5 0 0 0
8.96000
9 .8 2 0 0 0
8 .4 0 0 0 0
7.07000
7 .7 0 00 0
7 .3 5 0 0 3
7.14000
9 . 3o0 00
3.73000
3.68000
3.86000
3.77000
7.07000
4.27000
4.75000
4.89000
4 .9 7 00 0
5 .9 1 00 0
5.8 7 00 0
5.67000
6.06000
6.17000
TOTAL CM WATER AT 1 80 CM
8.66000
8 .3 7 00 0
8 .1 0 00 0
9.45000
4.86000
5.01000
5.04000
6 .1 6 00 0
5.35000
4 .99000
5
5.04000
5 .3 4 00 0
5.66000
5 .8 0000
5.65000
5.73000
5 .5 1 0 0 0
5 .6 7 00 0
6.18000
6
6 .1 5 0 0 0
6.25000
6 .2 9 0 C 0
6.06000
TOTAL CM WATER AT IBOCM DEPTH
6 .1 0 0 0 0
37.0300
36.5400
43.5700
36.8700
PLOT NUMBER
JULIAN
8023
MOISTURE CONTENT,
8053
C M .,
DEPTH
9.05000
13
7363
8085
AT 3 0 , 6 0 , 9 0 . . . C M
8.67000
J U L I A N DATE
TOTAL
805 3
C M .,
8.8 6 09 0
depth
36.9900
36.0900
PLOT NUMBER
12
Continued.
PLOT NUMBER
AT
39.2500
TOTAL
41.7800
8023
8052
15
DATE
7 318
8089
3 0 , 6 0 , 9 0 . . .CM CEPTh
38.4500
73b A
MOISTURE CONTENT,
C M .,
AT 3 0 , 60., 9 0 . . . C M
80P9
DEPTH
8.57000
9 . 16000
8 .8 5 00 0
9.41000,
9 .1 9 0 0 C
7.95000
8 .9 0 0 0 0
8 .8 2 0 0 0
9.31000
8.22000
7.91000
8 .0 1 00 0
9.1 6 00 0
7 .6 6 00 0
7.57000
7 .1 8 0 0 0
7 .1 7 0 0 0
8 .9 5 0 0 0
7.58000
7.45000
7.21000
9.51000
4 .1 0 00 0
4.61000
4 .8 3 0 0 0
4 .9 9 00 0
8.02000
5.76000
5.73030
5.63000
7.85000
4 .9 1 00 0
5 .3 2 00 0
5.43000
5 .34000
7 .5 0 0 0 0
5.96000
5.89000
5.76000
6.65000
5 . 9 9 CO 0
6.07000
6 .0 2 0 0 0
5 .9 6 0 0 0
6.80000
6.31000
(.5 70 0 0
38.8700
38.6200
47.1700
9023
3053
8089
t 8 1 a l °CM
WATER
42.3100
PICT
Ot M H s - 96000
42.4000
41.3700
6.15000
T S f A L 0CM WATER
36.3200
48.7600
TOTAL MOISTURE
37.9700
PLOT NUMBER 2A
NUMBER I A
J U L IA N DATE
J U L IA N DATE
7 318
O E P lH 6 - 4 6 0 00
8023
7363
CONTENT,
C M .,
805 3
AT 3 0 , 6 0 , 9 0 . . . C M
808 9
7318
7363
TOTAL MOISTURE CONTENT,
DEPTH
CM .,
AT 3 0 , 6 0 i, 9 0 . . . C M
DEPTH
8.8 8 00 0
8 .1 9 00 0
8 .6 4 0 0 0
9.12000
8.90000
8 .8 2 00 0
7.91000
8.40000
9 .0 5 00 0
8.64000
8 .5 9 00 0
7.89000
7.69000
7.89000
8.49000
8.58000
7 .6 5 00 0
7.43000
7 .7 0 00 0
8.35000
6.27000
6.47000
6 .1 5 0 0 0
6 . 1 COOO
6 .6 4 0 0 0
6.99000
b.85000
6.64000
6.62CC0
7.09000
4.70000
5.4 4 00 0
5.61003
5.5 9 00 0
6
4.82000
6.10000
6.04000
6 .2 2 00 0
6.84000
4.42000
4.74000
5.13000
5.4 3 00 0
5 .6 4 0 0 0
4.71000
5.53000
5.76000
5 .8 4 00 0
6.26000
5.58000
5.67000
5.73000
6.0 7 00 0
6 .1 7 0 0 0
6.16000
6.26000
6.60003
6.9 1 00 0
6 .9 6 0 0 0
6 . 11000
6.29000
6.19000
TOTAL CM WATER AT 2 IOCM DEPTH
6.53000
6 .6 8 0 0 0
6.35000
6.6 6 00 0
6.71000
44.5400
46.7600
48.5400
47.2500
49.0500
50.8900
44.6500
45.2500
TOTAL000 WATER
46.2000
Ii1IioE"
4 6 . 4 8C0
DEPTH
Appendix.
JULIAN
PLOT NUMBER 4A
OATE
7363
J U L I A N PATE
802 3
8053
TOTAL MOISTURE CONTENT, C M . ,
AT
808 9
7318
3 0 , 6 0 , 9 0 . • .CM CEPTH
7 36 3
TOTAL MOISTURE
8023
CONTENT,
C ".,
8053
AT 3 0 , 6 0 , 9 0 . . . C M
E089
Cf PTh
8.04000
8 .6 5 00 0
9 .5 0 0 0 0
8.76000
8.51000
7.99000
8 .2 8 00 0
8.64000
•.65 0 00
7.32000
6 .8 5 0 0 C
6 .6 0 00 0
8 . 4 COOO
8 .0 9 00 0
7 .2 4 0 0 0
7.01000
7.22000
7.86000
5.13000
5.17000
5.33000
7.10000
6.74000
6 .7 9 0 0 0
6.71000
6 . 7 2000
7.31000
4 .3 3 00 0
4.8 9 00 0
5.23000
6.50000
5 .5 7 00 0
5.76000
5.81000
5.94000
6.8 6 00 0
5.2 8 00 0
5.29000
5.65000
6.0 7 00 0
5.14000
5.40000
5 .6 0 00 0
5.78000
6.65000
6.2 6 00 0
6 .4 7 00 0
6 .5 9 0 0 0
6.77000
5.77000
5.85000
6.11000
6.3 9 00 0
6 .7 2 0 0 C
St8IJo
0Jh DEPTH 7 . 2 8 0 0 0
7.23000
7
7.02000
44.2200
50.8600
46.1400
47.7200
51.1000
905 3
8089
T0TAL°c2
WATER
43.2200
46.2000
TOTAL0? 0 WATER i r m
46.3700
PLOT NUMBER SA
8.52000
45.5400
J U L IA N DATE
736 3
TOTAL MOISTURE
DEPTH6 - 60000
PLOT NUMBER 6A
J U L IA N OATE
731 8
g ,
CONTENT,
8023
C M .,
7 .8 1 0 0 0
AT
805 3
3 0 , 6 0 , 9 0 . ..CM
8 .4 ,00 0
8089
DEPTH
7363
8 023
TOTAL MOISTURE CONTENT,
9 .0 9 0 0 0
8 .7 *0 0 0
7.73000
CM .,
AT
30 , 6 0 , 9 0 . . . C M
CE PTH
8.11000
8 .3 1 00 3
8.37000
8.44000
7 .8 1 0 0 0
7 .6 9 00 0
7.83000
8.48000
6 .9 2 0 0 0
6.65000
6.61000
7.46000
6.27000
6.50000
6.29000
6 .3 9 00 0
6.8 0 00 0
5 .4 2 0 0 0
5.3 4 00 0
5.25000 •
6.23000
4.1 2 00 0
5.63000
5.75000
5 .8 2 0 0 0
5.96000
3 .3 5 0 0 0
3.81000
4.43000
5.89000
5.08000
5 .6 0 0 0 0
5.64000
6
6 .1 0 0 0 0
4.49000
4.66000
4 .8 3 0 0 0
5.75000
6.13000
6 .1 9 0 0 0
6.25000
6 .5 4 0 0 0
6 .5 3 00 0
5 .7 7 0 0 0
5.81000
5 .9 8 00 0
6.29000
St4IJSJh DEPTH 6 . 5 1 0 0 0
6 .7 9 0 0 0
7.07000
5.9 5 00 0
6.10000
WATER AT 2 IOCM DEPTH
6.40000
46.0900
48.5000
49.7000
6.47000
TOTAL CM WATER
45.0600
46.5800
PLOT NUMBER TA
total
40.3700
41.5400
46.4200
SC 53
8089
J U L IA N DATE
7363
m o istu r e
39.6600
PLOT NUMBER 8A
J U L I A N DATE
7318
t8 t AL0? 0
CONTENT,
8023
C M .,
805 3
808 9
7 3*63
8 023
TOTAL MOISTURE CONTENT,
AT 3 0 , 6 0 , 9 0 . . .CM DEPTH
CM .,
AT
3 0 , 6 0 , 9 0 . .. C M DEPTH
8.53000
7.83000
7.95000
8.31000
8.35000
7 .8 3 00 0
7.61000
8 .1 3 00 0
8 .5 6 00 0
7.77000
7 . 84000
7 .3 9 00 0
7.28000
8 .2 0 0 0 0
7.67000
7.48000
7 .> 80 0 0
8.17000
4.56000
5.49000
5.45000
5.5 5 00 0
6 .0 2 0 0 0
5.3 5 00 0
5.45000
5 .4 1 00 0
6.16000
4.01000
4.90000
5.26000
5.2 1 00 0
5.55000
3.94000
4 .3 4 0 0 0
4.87000
5.46000
5.60000
5.65000
5.78000
6 .1 0 00 0
6.42000
4.95000
5 .2 4 0 0 0
5 .4 1 00 0
5.8 0 00 0
6 .3 0000
6 .3 4 0 0 0
6 . 1900C
6.5 1 00 0
6 .7 4 0 0 0
6.30000
6.22000
6 .3 7 00 0
6 .5 7 00 0
6.69000
6 .7 6 0 0 0
St6HMn DFPTH6 - ' 600 0
6.93000
45.6700
48.0600
42.9800
47.6800
T O T A l0 CM WATER
43.1600
St4JlOCH
44.5200
OCPTH6 - " 000
44.6700
TOTA?°?2 WATER
42.6300
*
44.2600
Continued.
PLOT NUMBER j A
65
Appendix.
Continued.
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33
l ib r a r ie s
3 1762 1001
N378
O e lle rm a n n , D. J .
S p r in k le r system i n s t a l
l a t i o n and m o n ito rin g
o f p la n t m ic ro c lim a te
Oe6
cop. 2
I S S U E D TO
DATE
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