A consideration of various factors affecting
the net duty of irrigation water
Philip Rowland Roosegaarde Bisschop
B . S . ( Uni v ersity of South' , jAtfr'i c a,) 9 18
In *e*da^ *l^^:v^^
Submitted in partial satisfaction of the requirements for the
MASTER OP SCIENCE
UNIVERSITY OP CALIFORNIA
Approved _ . ______
^/Tinstructor in Charge
Deposited in the University Library
81 ej? ?frjK>JWl.
Letter of Transmittal
Prof. Charles Derleth, Jr.,
Dean of the College of Civil Engineering,
University of California.
In accordance with the regulations
of the College of Civil Engineering, I herewith
beg to submit to you for your approval my Thesis
for the degree of Master of Science.
I remain, Sir,
April 30th, 1921.
llvlO '10 sgsIloO oriJ- lo .nso
isO lo ^*lfldvlc
siii ri'^iw sortsfcicoos I
nlgna HviO lo aselloO srl* lo
Ivoiqqa r iwot 'icl flb^ o.
a lo is^BBM lo
f * 1 a 1 a*t wo
TABLE OP CONTENTS p
Letter of Transmittal.
Definition of net duty and max-
imum economical duty
The Texture and Structure of the Soil . ,
Grades of soil
Structure of the soil
The moisture contained in the soil
Chapter III 28
The Climate ......... .........................
The annual precipitation and its
distribution ........ . .................
The start of the Irrigation System .......
Chapter IV 34
Moisture Distribution in the Soil ............
Downward, upward and lateral
movement of soil moisture ............
The extent of distribution ...............
Results of field experiments .............
Conclusions reached ......................
Chapter V 5^
Character of Soil and Subsoil ................
Gravel and sandy subsoils ................
Chapter VI 67
Ejrapj)ration, Percolation and Surf ace. J/asJbe
The process of evaporation ...............
Cultivated and uncultivated soils .....
Furrow irrigation .....................
The effect of the type of soil on per-
colation losses .........................
Size of irrigation head ..................
Frequency of application ..............
Length of run .........................
Lateral percolation in furrows ........
Surface waste .....
DOS -;t0b rfsn. lo
. -le a
I IOB srtt lo
lios srf- it - fbsniacffioo si.
.... a :
act I ,f>n-?
.u jaio/n IIoa ic tnsr.i.svo
oW.tjdl'T-taxb lo ^nsctxe
sir.i'ioqxs Mail 'to a^
. . b 9ri o B e^c 3 no 1 s .0 1 one U
bed' av Mi
Chapter VII 93
The Fertility of the Soil
Need of fertilizers
The function of organic matter in
Chapter VIII 99
The effect of irrigation at different
periods of plant growth
American irrigation practice on dif-
Diversification of crops
Chapter IX ]_ 9
Yields of Various Crops under :...VaryJLn
Amounts of Irrigation Applications
Results of experiments on
( 1 ) Alfalfa
(4 ) Citrus fruits
(5) Deciduous fruits
(1) The net and gross duty of various
irrigation projects for the year
(2) Distribution of irrigation water for
net duty on various projects for
the years 1912-1919
(3) Average seasonal duty of water on
various Irrigation Projects for
the years 1912-1917....
- r ii?) no soicfo^i.q n
. . . , aqoto
r ro ^ tsf ** v ^ o T / ct^//fe -^ o rr ^ i r- "
taw noli^'-I/nJ: 1o nol
(References are indicated by number.)
1. Soils Lyon, Pippin and Bucionan.
2. Principles of Irrigation PracticeWidtsoe.
3. Irrigation and Drainage- -King .
4. Irrigation Management- -Newell.
5. Irrigation in the United States - Teele.
6. Irrigation Practice and Engineering, Vol.I?-Etchevery.
7. Soils - Hilgard.
8. Physics of Agriculture - King.
9. Evaporation from Irrigated Soils - Portier and Beckett
- United States Department of Agriculture ,, Bulletin 248.
10. Distribution of water in the soil in Furrow Irrigation
- Loughridge and Portier, United States Department
of Agriculture, Bulletin 203.
11. Irrigation and Soil Moisture Investigations in
Western Oregon - W. L. Powers, Oregon Agricultural
Experiment Station, Bulletin 122.
12. Duty of Water investigationsDon H. Bark, Ninth Bi-
ennial Report of the State Engineer of Idaho.
13. The Duty of Water in Cache Valley, UtahHarris, Utah
Agricultural College and Experiment Station,
14. The Movement of Water in Irrigated Soils Widtsoe and
McLaughlin. Utah Agricultural College, Experiment
Station, Bulletin 115.
15. Yields of Crops with Different Quantities of Irriga-
tion Water - Widtsoe and Kerrill, Utah Agricultural
College Experiment ^tateion, Bulletin 117.
Em- nlqq Jt'3. , no -&I - -a I ioS I
oJt:*Ai8l - xiI lo aalqloalil -2
ifiB no i 4s si- IT: I -S
9LjS5"i. JJtTJ-' J.//0 L'l V
axe I loci bne 30 1:
i J-'iTa L. - -,:'.3;t "u , \;
'</*'? 4 o + '* "^^fc^'^"
16. Methods for Increasing the Crop Producing
Power of Irrigation Water - Widtsoe and Merrill.
Utah Agricultural College, Experiment Station,
17. Studies on Capacities of Soils for Irrigation
Water - 0. W. Israelsen - Journal of Agricultural
Research, Vol. XIII, No. 1.
18. Investigations of the Economical Duty of Water
for Alfalfa in the Sacramento Valley- -E. R. Adams.
19. Report on Irrigation Investigations nn the North
Side Minnidoka Project. Harding.
20. Water Requirements of Soils in the Sunnyside Valley
21 Report on Irrigation Investigations at Billings,
Montana- -Harding .
22. Flow of Irrigation Water over Soils in Different
Methods of Application- -Harding.
25. The Use of Water from the Tuolumne by the Modesto
and Turlock Irrigation Districts Etcheverry and
24. Depths to which different Soils may be wetted by
Irrigation Water 0. W. Isrelsen.
25. The_ Capillary Movement of Soil Moisture - W. W.
McLaughlin, United States Department of Agriculture,
26. Annual Reports of the Reclamation Service, 1912 - 1919.
27. Experiments of the Economical Use of Irrigation Water
in IdahoDon H. Bark, United States Department of
Agriculture, Bulletin 539.
28. Soil Moisture Studies Under IrrigationHarris and
Bracken- -Utah Agricultural College Experiment Sta-
tion, Bulletin 159.
39. Irrigation Projects Data E. A. Moritz, Vol. 9, No.
11, Reclamation Record.
jrf I ^ cmoT ^oiO sr 1 "^ -a-niaaoiorfl iol arsciiJefci .61
W . '
rc0, anol-^slJaeviil a
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oS Io e*nraMli;peH -le^sW .02
no let as XT'* I no tftoqaH 12
J:U nJ: > Tic- isvo 'ie^sW ccold-esilil /io wol r 'i .32
. ^rl^-TiT - aclctctoilqqA 'Io sbotl^s./t
rjoil -jectsW Io es.U siTT
.^: "eiG no i .t*^ii f sl xcoliJjT bne
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It is well recognized that, regardless of the
crop irrigated, a proper knowledge of the duty of water is
essential to both the Farmer and the Engineer. Such, es-
pecially, is the case in newly developing irrigated and ir-
rigable districts. With the growth and development of the
irrigated sections the question of advantageously and eco-
nomically using the limited amount of irrigation water is
becoming more and more apparent. As the irrigable lands
become more settled, more frequently is it asked just how
much water is necessary to produce a good crop, and under
what conditions of irrigation can the largest returns per
acre foot of water as well as pe r acre be expected.
In South Africa especially, in its present period
of development, is it essential that more definite informa-
tion on which to base an answer to these questions, be ob-
tained. It is a matter of extreme regret that up to the
present no experiments, to determine the water Duty of our
South African crops under the many varying climatic condi-
tions, have as yet been undertaken.
It is essential to the farmer and irrigator to
lo asslbifl^sT . -tar-d- fossirsfooe-i llsw al tfl
ai locfsvir Ic "^cfx/b ec'-t to Qgbei^cni. i^qc - iq s ^fcsct-s^liii qoio
-39 ,fiow2 ,i3srii,iiii aiict bi:& r f9rri r iB'>j. srl xl^ocf od 1
-ii brtB bsctjagiiTii gciqolsvab ^Xwsrt nl 0aeo axid 1 ai
-oos bitfj Yia^cQ^fid-nsvbs lo rcoictaaup srl^ enoJWaes JJ
ai -iod;.8w ncl.jB3ii r ii lo cj-m/ofon bs^lmll srW gniaw ^
a>nx?I aldB^iiiJ: s/'uf sA . ctaeiaqqa SIOJB bne eiorvi
tebror .bxiB ',qo r io Loorv^ aouboiq o.t Y~ ssa 3osn ai
ioc sni.^31 d 693^^1 siicf HBO nolJs^iiil lo anold'ibfioo-
.bsdoec^xa sJ S-TOB -i sq as Xiew SB IS^BW lo c^ool 9105
be it d-rfeaoiq a-j i n^.r^-L 210 ^^ BoxilA ii^efi nl
-aitnolnx scf inilsb s-xont d-Brf* Icid-nsass tfi ai tdroiuqclovab lo
-do 3o r , aaolj39JJp seerld- o^ iswsns HB as ,-ioldvr no rscid-
sx^ o-j qu Jsxid- ;t9 r i33'! o^sictxe .lo f i: rj si tfl ..bsrxiBJ
tcro. lo '^jyG loijew srf^ snim- ' xs on Jaag-
-tbnoo pid-Birrilo ^nlvr 1 ^^ &&& ^ -' I3 naoiilA xiv
baa - OB 30 ax
have this information that he may make the arrangement
for an adequate water supply, that he may avoid injury
of his soil through the application of too much water,
and that he may adjust to his land the amount available
to him, so as to obtain the largest possible returns per
acre foot of water applied. Further, he should have an
under standing /the underground movement of the water after
its application, that he may be sure, on the one hand,
that excessive losses are not occurring through deep per-
colation, and, on the other hand, that the irrigation wa-
ter is penetrating into the soil sufficiently deep to give
proper nourishment to the feeding roots of his crop.
It is essential to the Engineer to have such in-
formation at his disposal in order that he may determine
how large a canal to build to supply a definite area, or,
having determined the quantity of water available and the
cost of bringing it to the tract to be irrigated, he could
not decide upon the practicability of his scheme because
of his inability to determine how large an area the water
supply is able to serve.
The Engineer, too, should have an accurate know-
ledge of the factors that influence the amount of water
d7i9i::9 gneiss erid Q'Aan *Bm eii tfsitt nold'amio'irii aldd"
biovfi -sjjsm 9rf tferfd 1 . ijlqqtfe letfaw stffiifpsbjs IIB tol
jsw rloxiTH ood' lo nc/.o3CJcIqqs grid 1 jigxroidd' lioa sir! io
aidi^aoq cJ-sssiBi axfcf rriacfcfo oct as oa ,miii
rus svsrl blucila a;i (-is-dchritfi .bsllaqs r fs.tw Io oool
ij lo in9:,.avo;ri bajjO'i^-iaL.'.;. 9 ^ .'.";:. .:J'L ; 3 '':
xl ario s;y no ,31; /a -3d %&& && ^Bitcf , noli JB oil qqs aJi
o'ir'j yiliij/ooo ooc sis asaacl eviaaco.'.o l-aifcf
-aw ncid-a^iiil o^d" j/saj ,>isri laxid-o arid- nc -bas -a
vig ocf qsoa ^XofiDioillua Ixos end 1 o^ii gxiio^'icJ-onsq si
.qo r io a In io aci-co'i gnibosl sricj 1 o^ drxamfiaiixfor: r ioqoiq
rcl :, ; ojya avjezl od" issrii^n^-sii'd- od l^l^neeas si ctl
n gxi $s:L - r iobio ni laaoqaib aiif ;ts noictfir.^ol
.B3 r xs sciini'lab a ^Xqqire od" bii0d od" iBnflo B 93'i.el won'
>HB 9lcfGllj8v 'isd-sw I'o Tj^l^nBjjp &d$ bsnliTrssd-ab aniVBri
9. r [ .bod-js -.t'l-rl 9cJ od". d'oaid' sild 1 od* ctl ':icf lo d-soo
9axjBostf sKtsifoa aiii lo Y*-^ - ^ 30 ^^ 03 '^? d ^ noqjj sbioab ^ort
isdsw eti* asTB ne 9316! wod = '..ia'ani aid lo
- . t Ids ai T iq
worpi ad'B'-iDOOB HB o . . , ' ._ orJT
lo r: - odoaz ssij lo 9?
used to mature a crop after its application to the soil.
Such matters as the spacing of the furrows in orchard ir-
rigation, the length of run and the corresponding most
economical head of water to be used, frequency of applica-
tion are of vital interest to the success of an irrigation
Again, we shall not be able to place on our
statute books more logical laws concerning the proper use
of water, or to enable our judges to render more satisfac-
tory decisions in water disputes, until we have gathered a
large amount of data, under properly controlled conditions,
relative to the behaviour of water when brought upon soils
for the production of crops.
The "duty of water" is a phrase which expresses
the relationship existing between a given quantity of water
and the area of land that it is made to serve. This amount
may vary between the wasteful application of water on pre-
pared lands in an unscientific way to the highly refined
experimental methods as used for instance in Southern Cali-
fornia, Where according to P. R. Adams "the water carried
has the exceptional agricultural value of one thousand dol-
lars per miner's inch."
.Hoe add bd- noJtd-jeolIgqa a*! isdlB qo-xo -3 oii^jsm orf
jci awoiiul arid- lo gnloflqs slid- a.s
gnlbnoqasiioo erfd' bna run lo xidgnal
iiqqB Ic vons/fpsil ^>9au ecf o-t isd-ow lo S
i na lo aasooua artt oi d-asiodnJ: Isd"iv lo
no 903lq el slc f s 9C r d"oit Ilsxie aw niBgA
B.C- laci^ol 9-io,it asioocf
Oi oct a93&i(t ' I00 Icfsn9 o* 10 ,/ied-j3w lo
ii aiv Ifdnxr ,39-d-yqaiJb rred-flw r;i anoi^Ioal) '
q isfenir ,, ed-sb lo
alloa fioqu drl^.uoid neilw is^sw lo i0oJ:VBii3G f arid-
.aco^o lo ncldojyfcotq siicf
aesaatqxe ifola'w safi'iriq B el " f is>;tsw lo
xod-Aw lo ^d-ld-iuawp 9vl3 s usswa-sc
-niiOBta aliffi .evioa oj 9.0 BHI ai dl d-erid- fcrtfil lo BSIS edd
-6'iq nc 'lodsw lo rioictBDlIqq'B l.olsJesw 3.ij n ocf V 1 - 07
bsiil9i TjIiisM 9fd o* -^sw bilid03ian0 JSB nl Bbasl fi
-iiaD aiedd-jyoS ni sooed'snl 10! t: . ; a .oond-sin Isduamiis.
W Slid''' 8BU3&A -S -"5 O* OOOS ai9U>Y ,BirftOl
lo e, :oldqsox9 9fct ari
la' 1 - aisi
It is therefore, in order to be more definite,
perhaps advisable to use the phrase "the reasonable water
requirements," which may be defined as "the use of that
.",'iat by e
quantity of water which represents good practice when the
character of the soil, topography of the land, value of
the water, crop and other economic conditions are taken
into consideration." It is in general that quantity of
water with which the average farmer should obtain the best
results without undue waste.
iJ.Cii an ir-
It is, of course, obvious that this quantity
cannot possibly be permanently fixed and must necessarily
vary not only with the physical and topographical condi-
tions under which the water is applied, but also upon the
economic conditions affecting the value of the water and
the resultant crop.
It may be expressed as the number of acres that
may be irrigated by a definite quantity of water, usually
a second foot or eusec, flowing continuously throughout
the irrigation season. The most "commonly used unit is.
however, the acre foot, which represents a volume of water
equivalent to a depth of one foot on an area of one acre.
The Gross Duty for an entire System is made up
, sdlrrilab siom sd od rtsbio ol t e-so'i9'rorid- ai dl
arid" 1 ' as bsiillsb ac' . xioi.rfw ",aJn3rii3-_
lct nouw eoi^os-iq boog e^iiaasiqai 4o>nw tad-jaw lo ^i^nawp
3itf lo ijflqflisoqod 1 Iioe orfd 1 lo nsJoaisnp
t 3-iB anoint iDrroo olirtonooe isrlcto >HJS qoio ,'13-lsw orld"
lo ^d-id-iiewp ^snd- I.eisri93 at. 8,1 W " .nold-aisblerioc ochii
cf sxlit nisd-do blnca'a isnTifll ggaisva arid- xloitlw u'dlvf isdsw
sJr.'id: uB^io ewoivoo ,. saitfoo lo ,ai
n ctawrsi bns baxil Y-t ;i ' nsrism ' :9C i 9( ^ ^
-Ibnoc Ir;o.r:Iqj3 r isoqod- brus iBCie-jdq &tii dd"iw ^Ino don *^^ v
grid ncqu oalB dnd ,&9llqqjs ei 'isd^jsw edd 1 ifoliiw leJbru; aflold
bits 'iodBw arid lo saLav orld gnid-osllfl anoidibnoo olntoaooe
a 91 os lo iscL-jm ild a^ L . ^a oci -^JSK
dworf^wcirfd fclarrour ' ' -1 bncog-j a
, el ' . ' ' ' 'figxiii e
e.: - ; " ..... ;OS 3/ld t i::
a: - '-. ' . - :oiO 9..
of the net Duty and the Loss in transmission.
The net Duty represents the actual amount of
water delivered to the land and includes such losses as
that by evaporation, percolation and waste, in addition
to the actual amount that is absorbed by the plant.
The Gross Duty is the relation between the to-
tal irrigated area under the System and the amount of wa-
ter diverted from the source of supply. The factors that
influence the gross or entire duty of a Scheme are as
many and as varied as the conditions under which an ir-
rigation scheme operates. An attempt to summarize all
shown in the following table:
ni 3sod ailct bna 'tfsjQ $&n srld 1 lc
lo cfnifOffiB Lsirtos aJd- ed-rtsesiqsi Y*& cJ-grt sal
as a323oi rfox/a asiu/IonJL bns bnsl sifct od ba r i9vlle
nl t 3oasw bn& nolctBlooisq tnc.f.jjs'ioqsvo Tjcf d-
q 9.ci^ ^jcf bscfioads a I JailS driuoms isxjd'Ofl 9ilj
-ocf 9ilct ns8wd-sd noi^jsl.s r i 9.ci^ ax
lo drii/onfl 9ilct bnjs ^scfaYS erld-
91 IT .vlqqjLra lo 301003 8iW rrtorrl bect'isvib
3.3 o f i3 s.rteno^ B lo ^tub s-ildrie r io 03013
-ii HJS iJoirlw -isbrtL- anoicf Lbrioo sri^ as bei'-xsv aa b
'i 9rid- n nworfs
( ( OJ (Distribution
(Factors ( . f , , (Quantity
( (Rainfall (Distrlt)ution
(can be (Water (Fertilizing silt
( ( carried in suspension
vered as ( (Wind movement
(fixed (Climate fgggg?& Irri _ ven quantity of
( ( ( gation Season
(Losses in (Seepage
( ( (1. Distance from the
i i j. j-i i
( ( stream to the land
(Losses in ( (2. Soil through which
(Transmis- ( &l ( the ditch is built
( sion (S. Kinds of (Lined & Unlined
(Factors ( ( ( ditch (Cross Section
(which ( (Canal
(may be ( ( (Field ditch
(modified" (Rotation or contin-
( ( ( uous use
(Irriga- (Method of applica-
( tion ( tion
( Practice (Head used
( ( (Waste water
(Length of run
(Cultiva- (Dry mulch
( tion (Ordinary cultivation
( (Configuration of Surface
(Irrigable (Soil and subsoil
( lands (Reparation of the land
( (Ground water level
fcroos (Length of growing season
( (Diversified or not
(Factors (Faulty adjudication (Appropriation and granting
flnrl P.nm->+'. Hvi^avo I ~f _. _i_j j
( ( and Court Orders
(may be (
(cor- (methods of
( rected( payment
-_ rights to more water
( than is needed
(Based on quantity rate
(Based on flat rate
Jlla gni. '
noianaqawa nl bslTrso )
' ) 9 - flral - a ) baxil;
jiic r fl
>n.sl sHd- od" mBaid-e
rlpldw ilsi/ortrid- IloS.2)
j'll.acf al ilocfJ.fc srfcf )
^ bsniajlo afcnlA.5)
fi 3GC r iO) rfo-j-iJb )
c, } . a
9Bi/ S.U00 )
-BOilqqB 10 bofef8M)
no 1*. )
) gcf vant) 3HT OHIO
lloadua bna 1J
bnsi eil^ 1o noi a&niJl )
I9V91 19JJ8V. )
* bna noxjfliiqo'f od-
) ) /
i no .
All these factors do much to increase or de-
crease the area that may be served by a given quantity of
water. There remains, as a disturbing factor, the law
that the more water that is added to a crop, the smaller
will become the yield per unit of water served. This law
of increasing water cost raises the question of whether
the water should be used to obtain the largest possible
50 acre 'Inches 'Yield 'Total 'Price 'Grose ' t M.et
yield per acre or whether moderate quantities shall be
used to obtain the largest yield per acre foot of water
There is a depth of water for each type of land,
crop and water conditions, which will provide a maximum
profit. When water is added to a greater or less extent
the amount of profit will vary accordingly. It is only
with an increase of our knowledge of the duty of water
that this point of "optimum" water, or of maximum benefici-
al use, can be determined for different crops and climatic
The following example will illustrate this point
more clearly. (&)
A beet field is supplying beets to the factory
at a contract price of five dollars per ton. The total
cost of producing the crops, including interest on the in-
-01) 'jo sajsaionl: od rloim cfc 2 f otfOB'i 939110 1IA
lo ySlSttBUp nevig B ^d sviea ad ~am Jfliid
arid" .lodoBl gnidiLtfaib & a 3 . arciamei
r.e add" qoio B ci beabs ai d-BdJ isdav; siorci arid- d-jsifd"
elriT .&9visa isdsv; lo dir/xr isq blsl^ sifd 1 smooedllxv;
isrid-QjiIw lo noidae-up srld aoa'ifl'i daoo 'isd-BW giiiaaoionl "io
sidlsaoq dasgial sild- nlsdcfo od bsan sd bijjoxie isd-aw arid
sd IlBrfa seidid-nsup 3d\srisbom isrfd-aifv; 10
o dool 3-1 OB i aq blc-l^ d-asgiBl arid niadco od
Ic sq-od- doss iol lad-sr lo ddqsb B ai
irjjm'J:x.3fTi B abivciq IIi s ,v riolu'w t ano id Imc o tedaw br.a qoio
dnadxe aasl i-j isd-ssis a od bsibbs el isdav." neiiW .d-llo'iq
^Ino ai dl .YlsniE^eooa -^isv Uiw diloiq lo dm/orris add-
^^dsw lo ^d;/5 sr!d lo egbslworal IJLTO lo sasetonl ns rfdiw
-ioilsnsd murrixn-rr lo ^o ,iedsw "loxjircid-qo 11 lo dnioq siiid- dsad
oidamilo bnB aqoio dasisllxb c iol benxmisd-sb ed HBO , aexr IB
d;nioq aiad sdBid-sx/ili Iliw .:g gniwoliol
'i'cd-ofll arid od adssd s^- ;3 2 - t -A
ladod c .nod i9q o " - " 3 ;
-rti grid" nc ' ' ^^ C0
vestment, may be assumed to be thirty dollars per acre.
Tabler I may be then constructed on the basis of the crop
yield in the Utah experiments (see Bulletin 115, 116 and
117 Experiment Station) on the effect of varying quanti-
ties of water on the growth of crops.
'of wa- 'of
'ter on 'beets
21 ' $5
$ 60' $45
59 ' 5
56 ' 5
65 ' 5
120 ' 75
180 ' 100
240' 85 '
Prom the above, it will be seen, that the largest net aggre-
gate income, was obtained when the 30 acre Inches were spread
over three acres. When spread over more or less land this
amount decreased. The largest profit per acre was obtained
with a thirty inch application, being seven and one-half dol-
lars above that with the fifteen inch application. In the
table the cost of the water has not been taken into account,
19 q 3i.3l lob 1*1 irf* 9tf o*. benttraea ad \;3;r; t
qoio 34* ID a laser end- so bsda/rliaxioo tterfcfr ecf .^sm I
baa 811 .311 aitellwH $aa) stfitemtiiaqxe dad-Li 9di at
Ic do ell 9 arid no AaoWa*3 ^nerfiittcqxa VII
Ic ddviroig arid 1 ac IS^BW lo 3-3 id-
T t~" ' '
03. 75 '
. j -j
3V ' 021 ' 03 ' 3GI
! ! I
001 ' 081
08 ' .dSSS
blalZ' ae/foj-il 1 si os OS
. - r
8.8I j r
Jan ctasaisl 3dd osncJ .ri^sa ad Xllw d~i <9vocfa arid 1
si 9 '.T aaxlonl 9'ioa OS eifd rt9riw banlsjcfo asw ,3i?too:
ild- brial aaal 10 siorn isvo bJ39iqa fiadtf .as^oa 99ic!cf -IQVO
asw 8'ioa-/i9q d-lloiq dassial 9rfT .ftdaaonosf) iiroras
-Io& llaxl-aao bits navsa 3ni9d ^nold-aoilqqB rloni' ^d-ix
.noWaolIqqa danl nse tiw d-arf* svodfi a-xsl
oini najiad need .ton a- i i r arid lo iaoo grid-
and the question of what is the maximum economical yield
will therefore be dependent on whether the surplus profit
of seven and one-half dollars will compensate for the cost
of the extra fifteen Inches of water applied. Similarly
in the fifteen and ten inches application, the maximum