The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
site maintained by the Florida
Cooperative Extension Service.
Copyright 2005, Board of Trustees, University
3ary D. Lynne
John H. Williams
John E. Reynolds
,Re port 99
o "/ '>
C os' s
of Vegetable Irrigation
in Dade County, Florida
Food and Resource Economics Department
Agricultural Experiment Stations
Institute of Food and Agricultural Sciences
University of Florida, Gainesville 32611
Water is important to vegetable production in Florida. Competition
for water supplies among several uses will have effects on the vegetable
industry. This report provides information on the costs of water use for
vegetable production in Dade County. The average annual cost per thousand
gallons was estimated to range from $0.40 to $0.90, comparable to costs for
residential and commercial users of water in the same area. Informed
decision making by the current water institutions will be a necessary in-
gredient to improved water management. The analysis provided in this
report adds to the set of knowledge needed.
Key words: Water allocation, irrigation costs, agricultural water use,
The authors wish to thank the many agricultural producers in Dade
County that so willingly gave of their time to help provide needed data.
A special thanks is also due county extension personnel in the Dade
County Extension Office for their advice and encouragement. This publi-
cation also benefited from the reviews of Roy Carriker, Arden Collette,
and Cecil Smith. Remaining errors in presentation and interpretation are
those of the authors.
TABLE OF CONTENTS
LIST OF TABLES..................................................... ii
INTRODUCTION.......................................... .... ... ...... 1
AN ECONOMIC FRAMEWORK FOR ANALYSIS................................. 3
IRRIGATION COSTS FOR DADE COUNTY VEGETABLES AND SOME POLICY
SUMMARY AND RECOMMENDATIONS...................................... 14
APPENDIX.............. .......... ............. ........ .............. 18
Procedures for Calculating Water Level Estimates............... 19
REFERENCES ...... ............. .......... ... ...... ........... 23
LIST OF TABLES
1 Average size of firms (acreage), yield, operating costs,
and investment levels for selected vegetable crops, Dade
County, 1975-76. 8
2 Average annual costs and investment levels by type of
irrigation system for tomato production in Dade County,
Florida, 1975-76. 10
3 Water per acre and costs of irrigation for all irrigation
system types by selected vegetable crops, Dade County,
4 Average irrigation water applied and annual costs per acre
inch by irrigation system type, tomato production in Dade
County, 1975-76. 13
1 Hypothetical water levels for three 40 acre blocks of
tomatoes in Dade County, Florida. 20
CHARACTERISTICS AND COSTS OF VEGETABLE
IRRIGATION IN DADE COUNTY, FLORIDA
Gary D. Lynne, John H. Williams, and John E. Reynolds
Vegetable production is an important economic activity in Florida with
farm sales reaching $448 million in 1976 [3, page 12]. This represents 18
percent of the cash receipts from all of Florida's agricultural products
for that year. Tomato production generated the most cash value at $162.6
million (or 36.3 percent) of all vegetable sales and about 6 percent of
all farm sales. Dade County was a major contributor to this production,
with $85.0 million in tomato production . Because of its location in
the southern-most tip of Florida, Dade County is a major supplier of
A readily available supply of water contributes greatly and is a
necessary part of the production of vegetables in the state. In the
south Florida area, including Dade County, about 67 percent of all vege-
tables were irrigated (calculated from data in ). In Dade County,
about 80 percent of all the vegetables are irrigated, with all the toma-
Based on total sales of $2.53 billion [4, page 1].
LYNNE and REYNOLDS are Assistant and Associate Professors, respective-
ly, Food and Resource Economics Department, Institute of Food and
Agricultural Sciences, University of Florida. WILLIAMS is a former Grad-
toes, squash, and cucumbers irrigated (from data supplied in ).2
Continued population and economic growth has put pressures on the
water resources of the state; as a result, water has not been always
available in unlimited quantities to the vegetable industry. In 1971,
there were shortages in the Dade County area. Vegetable producers were
asked to reduce withdrawals for irrigation . It is expected water
availability problems could become severe in the southeast Florida area
by as early as 1980 .
The 1972 Florida Water Management Resources Act was passed to deal
with the problems inherent in a growing socio-economic system such as
that prevailing in Florida. Water management districts have been
created and Governing Boards appointed . Consumptive use permits are
already required of irrigation in 3 of the 5 districts. The water man-
agement districts, in turn, have the statutory authority to restrict
water use to that approved on the permit or any lesser amount the
district deems appropriate at any given point in time .
As a result, the 1972 Act could have substantial economic impacts on
all agricultural water users, vegetable producers included. It is too
early to determine long run impacts. Estimates of future impacts would
be speculative. It is already apparent, however, that by requiring
consumptive use permits water districts and their Governing Boards are,
or will be, allocating water among competing uses over time and space.
This means at some point, assuming ever increasing demands on a finite
resource, the Governing Boards will have to make very difficult decisions
A similar situation prevails in southwest Florida. Virtually all of
the tomatoes grown in that area in 1969, for example, were irrigated [6,
pages 64-65]. About 75 percent of all vegetables grown in that area
received at least some irrigation water.
as to how much water to allocate to vegetable production in Dade County
as opposed to commerce-industry, residential, recreation, and environmental
demands for water in the county or area.
It thus becomes important for those concerned with water management
to understand the nature and characteristics of the various water using
systems. Decisions which affect the availability of water for vegetable
production should be made with adequate information regarding the impacts
of such decisions. Only informed decisions by the Governing Boards will
give adequate consideration to the well-being of the vegetable industry
and the relationship (and contribution) of the industry to the public
This publication reports on the costs of vegetable production in Dade
County with particular reference to the relationship between these costs
and decisions regarding water use, management, conservation, and develop-
ment. Data for this report are derived from a larger study which has as a
major goal the estimation of the economic demand, and hence the economic
value, of water in irrigation. That effort is still in process.
AN ECONOMIC FRAMEWORK FOR ANALYSIS
Vegetable producers combine various factors of production to generate
a product to meet demands in the market place. Land, labor, water, capi-
tal (equipment, fertilizers, pesticides, etc.), and management are all
merged in a production process with the various interactive aspects of
nature to produce tomatoes, sweet corn, squash, pole beans, bush beans,
and other vegetables in the Dade County area. Water is an integral part
3ostof the results reported herein are from a study by Wlliams .
Most of the results reported herein are from a study by Williams .
of these production processes, and like all inputs to production, there
are costs associated with its use. More accurately, there is a cost
associated with use of the services of water just as there are for the
services of land, labor, capital, and management. The magnitude of the
yield per acre is a direct result of the manner in which these services
are organized and combined to produce a crop.
Some substitution is usually possible among the various inputs to
production. At least over limited ranges, for example, more fertilizer
can be substituted for less water to achieve a given yield. Similarly,
it is conceivable that more capital and/or more labor could be substituted
for some water, thus reducing water use. Investment in more efficient
irrigation equipment could reduce water use. Similarly, a more highly
skilled and attentive labor force may be able to increase productivity
from any given amount of water.
Vegetable producers are currently using a particular mix of resources
that are the result of substitution decisions made over years of produc-
tion effort. This mix of resources has been influenced by trial and
error, research results, and purveyors of farm equipment and other farm
inputs. In addition to these reasons, vegetable growers have adopted
particular technologies in response to price and economic conditions pre-
vailing over time. Given opportunities to substitute among inputs in
production, relative prices of inputs play a role in determining the
least-cost mix of inputs required to achieve a given yield. If the price
of a resource is low relative to other resources, an individual attempting
to maximize profits will use greater quantities of that resource relative
to other resources in the input bundle. With respect to water, the
"price" has been the cost of applying the water to the field during the
production season. This "price" has probably been relatively low and
relatively stable over a number of years, encouraging the adoption of
water-using technologies and irrigation strategies that reflect this
relatively low price.
The past set of economic incentives has encouraged the use of large
quantities of water. Also, experiment station recommendations have been
to apply water with the aim of maximizing yield, given the level of other
resources applied (see, for example, ). This level of application
coincides with the profit maximizing level under conditions of "inexpen-
sive" (costs approaching zero) water resources. With no competing demands
for the water supply, such irrigation practices made good sense, both
from the standpoint of the individual irrigator and from the standpoint of
regional economic productivity.
Policies implemented by water management districts through their
governing boards could have the effect of changing the relative prices in
the input bundle (for example, by raising the cost of getting water via
requiring permits), causing resource substitution in vegetable production.
A change in the mix of inputs, in turn, is likely to cause a change in
yield per acre. Whether such adjustments produce a net benefit to society
depends on the extent of loss to vegetable producers compared to the gains
made by other users of water, resulting from a reduction in irrigation.
Projections of impact on vegetable production from increases in the
cost of irrigation water (or decreases in the availability of irrigation
water) requires knowledge of the marginal (incremental) costs and marginal
Strictly speaking, the water level associated with maximum yield
should be applied only when the "price" of water is zero. However, under
highly uncertain field conditions a recommendation of maximum yield water
levels may also be appropriate when water "prices" are very low, relative
to other input costs.
response (in yields) associated with incremental changes in irrigation
levels. Unfortunately, marginal cost and response data are not available
for vegetable irrigation, and their acquisition poses difficult problems
in estimation. However, estimates of average operating costs and invest-
ment levels for production of vegetable crops in Dade County were deter-
mined .in this study.
Limited inferences concerning probable effects of alternative cost and
availability scenarios for irrigation water can be drawn from average cost
data. With some qualification,5 we would expect the following to be
descriptive over the long run:
a) a change in the cost or::availability of water for irrigation
will have the greatest impact on the production of those crops
where costs for irrigation are a high percentage of total costs
b) a policy which affects the investment in irrigation systems will
have the greatest impact on those crops where the investment in
irrigation equipment represents a large portion of total cost
c) in the case where the marginal factor cost of water is either con-
stant or increasing, the average cost per gallon of water delivered
to a crop is a minimum estimate of its value in that use. Thus, a.
comparison of the "price" paid by irrigators with that paid by
residential and commercial or other municipal water users is possi-
ble from average cost data.
Such inferences shed light on the answers to such policy questions as:
a) Which of the vegetable crops grown in Dade County would be most
affected by an increase in the cost of irrigation water or a de-
crease in the availability of irrigation water?
The major qualifications are that the producers must be functioning
in a highly competitive industry (pure competition) and have nearly perfect
knowledge. In addition, the current producers would have to be in a long
run equilibrium position. These assumptions may be rather heroic for the
vegetable industry in Florida, and particularly in Dade County. However,
there is in fact a high degree of competition in vegetable production and
producers may be striving toward a long run equilibrium because of the
need to keep costs low to survive. Only further research can verify or
deny these contentions.
b) What types of impacts and changes are likely given increased
water costs and/or reduced water availability?
c) Can vegetable irrigators afford to pay as much for water as
residential and commercial or other municipal water users?
IRRIGATION COSTS FOR DADE COUNTY
VEGETABLES AND SOME POLICY IMPLICATIONS
Production cost data were collected from Dade County vegetable
growers during the 1975-76 production season . Data on tomatoes,
sweet corn, squash, pole beans, and bush beans were obtained. The number
of observations and acreage surveyed for each crop is presented in Table
1. For each firm, data on total operating costs, irrigation operating
costs, total equipment and machinery investment, irrigation equipment
investment, system type (drip or sprinkler), and some limited information
on amounts of water applied were gathered.
Annual irrigation costs as a percentage of total annual operating
costs, which may be an indicator of relative sensitivity to water supply
and price policies, varied considerably among the crops. Irrigation
costs as a percentage of total annual costs were lowest (at percent)
for tomatoes and highest (at 16 percent) for squash (Table 1). This
implies that output of squash would be affected relatively more by any
given change in the price or availability of water, barring consideration
of possible off-setting factors such as a relatively strong market price
There was also considerable variation among crops with respect to
proportion expended on machinery and equipment investment and other costs.
This will be an indicator of sensitivity if the industry is near a
long run competitive equilibrium, To the extent there is divergence,
the percentage expended in different categories is not an indicator of
output response (see footnote no. 5).
Table l.--A si-rase size of firms (acreage), vield, operating cc;ts, and investment levels for selected vegetable-crops, Dade County,
No. Acres Boxes ---------------Dollars-------------- --------Percent-------- -----------Dollars---------
Tomatoes 1S 322 476 37 2287 30 283 (2637 1.2 10.7 11.9 393 153 546
Sweet corn 4 454 194 38 651 32 79 800 4.0 9.9 13.9 304 158 462
Sclash 7 218 173 34 941 30 154 1159; 2.6 13.3 15.9 370 149 519
Pole7 beans 7 356 306 42 1255 21 97 '415( 1.5 6.8 8.3 200 104 304
Bush b-=s 5 572 96 43 583 19 88 733\ 2.6 12.0 14.7 226 93 319
Number of individual observations obtained in the survey.
b.Rntal rate in area (For comparable land if owned land).
C'.nnual irrigation machinery and equipment costs (ME) represent an assumed 10 percent return (opportunity cost) and a 10 percent
depreciation charge on machinery and equipment investment.
Inclu'd.: interest of 9 percent on operating capital for the growth period of the crop: 14 weeks s for tomatoes and corn; 12 weeks
for squash:; .nd 10 weeks for beans.
eIrrigation equipment costs (ME), other irrigation costs, and .total irrigation costs as a percentage of total costs per acre.
The av.rge yield for the sprinkler irrigators was 465 boxes and for the drip irrigators 504 boxes.
Interpretation of the results is again similar. The results suggest sweet
corn output response would be the greatest for a reduction in annual costs
of machinery and equipment investment. Again, caution must be exercised
in use of this interpretation in policy matters, as it depends on long run
equilibrium positions being realized.
Tomatoes are grown under both drip and sprinkle (big gun) irrigation
systems in the area, permitting comparison of costs between two systems
on a given crop. The portion of total annual costs accruing to irrigation
averages s6 percent for drip systems and IM percent for sprinkler systems
(Table 2). This difference in percentages is not dramatic, but it suggests
that those tomato producers with sprinkler systems may be slightly more
responsive to changes in costs of irrigation water (Table 2).7 However,
slightly higher overall production costs and higher average yields for
tomatoes produced under drip systems suggest that other factors besides
relative irrigation costs for the two systems will influence the response to
changes in water policy.
Additional insights may be gained by comparing average water use per
acre and average cost per unit of irrigation water delivered by crop
The range in annual irrigation costs per acre was larger in both a
relative and absolute sense for the sprinkler systems. This may reflect
the relative age of the two system types in the area; i.e., the drip sys-
tems were all relatively new and all reflected about the same "state-of-
the-art" in terms of equipment types and operating characteristics. The
sprinkler systems have been used more years, with the possibility that
producers employ a wider variety of equipment type and age, and different
operating strategies causing costs to vary more.
The procedure for arriving at these estimates is discussed in Appen-
Table 2.--Average annual costs and investment levels y *ype of irrigation system for tomato production in Dade County,
Drip Sprinkler (big gun)
Average Per-b Standard Average b Standard
Item per cent Range deviation per Percent Range deviation
--Dollars-- -------Dollars------- --Dollars-- -------Dollars------
non-irrigation 2451 80.5 1700-3003 528 2275 91.7 1863-3003 322
irrigation 594 19.5 354-1074 277 205 8.3 48-476 136
total 3046 100.0 2659-3358 314 2481 100.0- 1939-3252 359
M and E investment-
non-irrigation 459 72.6 178-821 230 368 71.9 174-901 188
irrigation 177 27.4 119-250 51 144 28.1 75-306 72
total 636 100.0 544-1,071 272 511 100.0 264-1,039 216
Acre inches Acre inches Acre inches Acre inches
Water per acre
irrigation 5.8 43.1 4.2-7.2 1.14. 11.1 61.2 7.0-15.4 2.4
precipitation 7.7 56.9 6.2-9.2 1.35 7.0 38.8 5.2-11.1 1.7
total 13.6 100.0 11.5-15.1 1.53 18.2 100.0 14.4-22.5 2.59
aThere were 5 observations on firms with drip systems and 13 with sprinkler systems.
bNon-irrigation and irrigation costs as a percent of total costs, for the cost estimates. Irrigation water
applied and precipitation received as percentage of the total, for the water per acre variable.
CIncluding 9 percent interest on production capital, a 10 percent opportunity cost on M and E investment, and 10
percent of M and E for annual depreciation charge.
"This is the investment level ner acre based on producer estimates of the current market value of machinery (1) and
(Table 3) No dramatic differences among crops are a;.p :-re:- in the acre
inches of water appliedd during the production season, with 10 acre inches
for tomatoes and sweet corn and 7 each for squash, pole beans, and bush
i',. average "price". of water to irrigators.in "i. County was highest
for tomatoes at an estimated $1.19 per thousand gallons and lowest for
sweet corn at 41 cents per thousand gallons. Clearly, water is not "free"
to the i r r.:-ior. The -,:-ril.:e price paid by residential users in Dade
County in 1974 was $0.28 per thousand  and for commercial users :in the
county was about $0.80 per thousand gallons in 1976 .
The higihet-- average cost per thousand gallons was paid 1. tomato
growers-using drip systems. Drip irr>." t-r': paid $3.78 per thousand as
compared with $0.68 per thousand, or over 5 times the cost incurred by the
sprinkler irr;i irt.-.n (Table 4).
The unit costs in Table 3 were calculated from total annual costs in
Table 1 in the following manner:
ACA. = average costs per acre inch for crop i
TC.' = total annual cost of irrigation per acre
A. = acre inches of water applied during the production season
ACG. = average cost per thousand gallons applied to crop i
F- = conversion factor, from icre inches to thousands oF
gallons, F = 27.1543.
Table 3.--Water per acre and costs of irrigation for all irrigation
types by selected vegetable crops, Dade County, 1975-76.
---Acre inches--- -------- Dolls---------------
Precipitation received at Hcnestead Agricultural researchh and Educaticn
Center, plus irrigation water applied (see the Appendi::).
ACA is "average annual cost per acre inch."
ACG is "average annual cost per thousand gallons."
Table 4.--Average irrigation water applied and annual costs per acre inch
by irrigation system type, tomato production in Dade County,
Drip 5.8 594.59 102.51 3.78
aACA is "average annual cost per acre inch."
bACG is "average annual cost per thousand gallons."
The much higher costs found for drip systems may have implications
for water allocation decisions at the water district level. The physical
efficiency of the drip system is apparent, with sprinkler systems using
nearly twice as much water. However, the economic efficiency of the drip
system needs to be examined further. The additional costs (on the z
to use the drip system were $389 per acre, or a cost of $73 for each acre
inch of water saved ($2.71/thousand gallons). The producer would bear a
substantial burden, then, to save water
It is, of course, conceivable the producer cost of $73 per acre inch
saved is justified, in a social efficiency sense. That is, if the
economic productivity in other uses of the 5.3 in.-'es saved exceeds the
economic loss to the tomato growers, economic efficiency is improved by
the switch to the drip system. However, the distributive effects (income
transferred from Lo:n'ato growers to other segments of the regional economy)
may not be socially desirable. In any case, it is very important to -....
there are distribute i.on and efficiency effects of decisions and recomr
resulting from water district actions. These economic effects must be
considered, in addition to physical efficiency, in such decision prot
SUMMARY AND RECOMMENDATIONS
A large proportion of all vegetables grown in Florida are irrigated.
Water of suitable quality and quantity is in demand by vegetable growers
throughout the state. This demand is in competition with the water demand
by resid rntial, commercial, industrial, recreation, and "natural" uses,
(Th implicit assumption of this analysis is that yields are i
under either system. Yields would have to be about 76 boxes per acre
(1975-76 prices) from the drip system to make th' t.wo systems comparable
.in I he c'conomic returns to lie farmer.
as well as for irrigation of other agricultural crops. The 1972 Water
Resources Act was passed to alleviate conflicts and reconcile diEferences
as the different water users compete for the finite supply of water, which
is becoming a more scarce resource with each passing year.
Producers were asked to reduce irrigation withdrawals in the Dade
County area in 1971. According to planning documents recently published
by the water district in the south Florida area, water "shortages" will
occur in the not too distant future. It becomes important, then, to under-
stand the major characteristics of vegetable irrigation systems ;a; a step
toward informed decision making regarding water allocation and management.
The well-being of all Florida residents, as well as those directly associated
with the vegetable industry, is better served by informed decision making.
This publication provides information on the costs of irrigation in Dade
The Framework used in the analysis is predicated on the fact that
services from various production inputs (labor, fertilizer, pesticides,
water, etc.) are combined in such a manner as to generate different yield
lcvels. There is, in fact, an economic optimum level of input usage asso-
ciated with the prices of resources and products although in practice the
optimum may be difficult to identify or to achieve. Resources or pro-
duction inputs can be and are substituted among one another as production
methods evolve to ultimately generate the maximum profit level of output.
The current "mix" of resources devoted to vegetable production in Dade
County reflects the efforts of growers over a relatively long period of
time to adjust to economic conditions given available technology and know-
tedge of production relationships. The water use levels and irrigation
technology, for example, probably reflect the fact that water has been
relatively inexpensive and readily available over a long term period. The
rules'and regul!aio-s that reflect the policies cf :ater zeanaement disti :
can cause resource substitutions rnd pr5oductic response Vhich ay or -ay
not be the hi-'- s valued or =ost desired pcsib-e result.
annuall (crop year) irrizaticn costs varied frc- SS. -- acre for
bush beans to .313 per acre for to-atoes. Irriat--- c-sts an a percent
of total annual costs ranged fro- S percent for pole beans ct 16 percent
in squash production, suggestin-. that squash production o-2 be the -ost
responsive to changes in the ccsts of irrigationn. io.evr, the-re -ere
several lii-taticns in the data, that are discussed further below.
Aver-age cost of 'water per acre inch applied varied from S11.10 to
$32.43 across the crops in survey. This :_ves a ra-e of S.1 to $S.19
per thoi.nd gallons, values which are very sim-ilar :c -water costs paid
by residential and commercial users in Dade County during the sa~e period
of time. Esti-ntes of average water applied ranked frc- 7 t: 10 acre inches
per acre, over all crop types.
Data were collected on drip versus sprirnlcr irricaticn costs and
features in tomato production. Drip irrigation used 6 acre inches c w after
per acre. as co-pared to 11 acre inches, by the srin-ker irriaz.trs. Drip
irrigators also expn-ded -ore for inputs and received -igher yields, on
the average, than their sprinkler irrigator counterparts, -,:Z:e Lr; c-ore
intense itiput usage by the drip irrigators.
?"*.-.r":c costs of irrigation water were $102 per acre inch under the
drip system as compared to $18 per acre inch with sprinkler systems. There
was also a large variability in water supply costs by irrigators having thet-
same type of system, Fsu:"-e.tin; diffrn .-e:-:4 in efficiency in the irri,::;;:tion
A survey report of chiM kind does not lend : --i :TI to *.,;: '.iity .e, -."
*i. .:::.' .-ng '-:i- : conclusions -' .'...'., there are several considera-
tions t!hi: evolve fIr : th.- ror.''tNing which provide in-~i'l.t as to whete
future research --f forts should be dir-.cec.!:
1. Annual irrf --t i.on. costs are not a large share of :-.s tot I annual.
.:~r- ictle production costs. 'i.'.c,.-.;, tri.- cannot be ignored; any
.significant increase in such costs will most likely lead to.re-
source substitution (reduced water use) and reduced ;--. :i_ ...
2. r-.- c levels resource use (ici.luJin'!i water use) and the
current mix of such use is rho- result a ;: term" :-'. -::.
.p..-rn-..-; by the tnv..,l r-, a riod during which water has been-re'adily
.:-.' Ir:.:'ion A:-Lr.,..i :_ and investment levels in particu-
lar irrig:it to, system Lype ,'rWi' ] J.. ,L -water in the
past. Th:.-, !!..:.:,r- in the "rules-of-the-game" toward higher water
cost and less water availnC'-: y .water 7-. .-:.. 'districts
would have n-,.:t ive -i'VC ct; on ve.:.-.oabiT production add the growers,
which may or may not be in the best interests of society.
3. Water is not free to '. .rt.ble Z.va.''r.I in D0i3 County. In fact, the
costs of water use .:''..-.- higher than the costs borne by residential
Users. Also, for two of the crops, the-costs were -: g than for
c. '*'r'-Lal users,
4. The costs-of drip :irrTi.-;: L; were consider, -: .:- (over 5 : -.)
than sprinkler irrigation, for tomato i-i.-,.. ,rs. If yields were'the
;.-. this implies that economic .: :-'iiency '" the -.ar". irn level)
is considerably lower with the drip system, 'iC,- .' .. : ef.T- n
of O'itp F...l:o.-, however, is liilr.-r ()pr irnklers u.A;1 nearly twice as
much water). The income-distri.:Y': ?- .* economic -fficiency ef-
fects, must .e considered in addition to h: i -i- .'ci-., the
water -wa '.-'c.'T:' districts.
5. Data sources must be .l,...''lop1'd to, facilitate estimates .m 'i:.nr;-: ;.il
yield response and i.i'-.1: 1 costs. All *r:-.'. r:s concerned with pro-
fits should have knowledge.',' these marginal conditions. This is
'also true for the water r-. i m:',.:-mL 'districts .b1ar;-,..'d with ala .at in.,
water in the public interest.
- A enveat is also i.,cOrt L .t at this juncture: the notion that the r,''..'nn;.',
." total annual cost devoted'to ir'; ,itfIo can be :'- as aa measure oaut-'
put r' i'': m-' :.-:: ay be-tentous-. Its vni-'li~3 ". is tot:!" .1-:. .i'Alcn. on the
dttgre; to which '! i' o' L.. Lt. ,b i e i .ndtn try 'al.-'., ip.ro Kt s the conditions of' a
purelyy, cne.nii,,-ve Industry in oni. run equilibrium. Only further res~arc
can give answers to these issues. 1hr economic 7" -' .:1 quantity of water
use in vegetable production also cannot be deter-i-ed fro- these results.
The estimated after r use levels herein were based c several assutions,
discussed in tihe Appendix. C .ly further research, -here due conideration
is also given the economic di-ension, :ill generate data en the appropriate
water de-and levels for vegetables grc.mn irn D'e Conty.
'emc:;,ble sro--ers -ust and :.ill adjust t. changrin. ecor--ic ccnditions.
The prevailing water institutions influence the "rules-of-th, -a-e'" which
in turn ;:rfect these, conditions. This publication is a first step toward
help ing both the grov:er and the --ter manager better understand the eco-
nom.ics oi vegetable irrigation, --h ich should ultiL-tely inprcv decisions
re;,ardi::r' after r management.
PROCEDURES FOR CALCULATING WATER LEVEL ESTIMATES
PROCEDURES FOR CALCULATING WATER LEVEL ESTIMATES
Very few of the producers surveyed had records of water received (from
precipitation) and/or applied with irrigation systems . Thus, an
estimation procedure was necessary, based on each producer's best estimate
of how much water was actually used (or how long a pump was operated) on
each acre. Producers were asked to describe their irrigation strategy.
Most indicated a fixed strategy with smaller amounts applied per week during
"startup" times and larger amounts (again fixed amounts per week) applied
during the growing season for the crop. Generally, most producers indi-
cated approximately one inch of water was applied per week during the bulk
of the growing season. Some producers indicated if an inch or more of
precipitation was received during any particular week they did not irrigate
that week. This knowledge was used in conjunction with estimates of
precipitation received at the Homestead Agricultural Research and Education
Center to estimate water used on a particular acre for a particular pro-
ducer. The procedure used is best illustrated with reference to Appendix
A hypothetical situation is depicted in Table 1. The hypothetical
tomato producer has a total of 120 acres planted a week apart, starting
with the llth of October. This gives three weeks of harvest starting with
the 10th of January and completion of harvest during the last week of
January, starting with the 24th of that month. This hypothetical irrigator
is shown to pump 15 minutes during the first week (right after planting)
and to pump 45 minutes each week (except when an inch of precipitation is
received) until the last three weeks, when each well is pumped 50 minutes.
The approach used in calculating the water use from the data in
Appendix Table 1 is represented by the following set of equations:
Ap;enALx Table l.--lypothetlcal water levels for three 40 acre blocks of tomatoes in Dade County, Florida
Planting, irrigation, and harvest datesb
s a ells 10/11 10/18 10/25 11/1 11/8 11/15 11/22 11/29 12/6 12/13 12/20 12/27 1/3 1/10 1/17 1/24 Total
( (ai) P M P M P H P M P M P PP M P M P M P M P M P M P. H P M P H Pi
41 25 .20 15 1.19 0 1.20 0 1.08 0 .05 45 .03 45 0 45 0 45 1.19 0 0 45 .14 45 .26 50 .06 50 .02 50 5.42 435
41 25 1.19 0 1.20 0 1.08 0 .05 45 .03 45 0 45 0 45 1.19 0 0 45 .14 45 .26 50 .06 50 .02 50 .08 50 5.30 470
4' 25 1.20 0 1.08 0 .05 45 .03 45 0 45 0 45 1.19 0 0 45 .14 45 .26 50 .06 50 .02 50 .08 50 .02 50 4.13 520
12- --------- ----------------------- Not Calculated--------------------------------- --------------- ------------------------------------ ---- -. 14.85 .1.425
aMeasured in acres.
bDates used to signify the entire week of activity.
CPrecipitation () measured in acre inches received for the week and minutes (M) wells pumped during the week.
WI = (F )(C) E H M. (1)
WP = Z A P. (2)
WT = WI + WP (3)
A = A. (4)
IWA = (5)
PWA = (6)
W = IWA + PWA (7)
where (all variables defined for a firm for a season):
WI = total water used for irrigation, in acre inches,
F-1 = conversion factor from gallons to acre inches [F-1=(1/27,154)]
C = capacity of irrigation pumps, in gallons per minute,
H = number of wells in block i, i=l, 2, ..., m,
M. = number of minutes each well pumped in block i,
WP = total water received from precipitation, in acre inches,
A. = acreage in block i,
P. = precipitation received on block i,
A = total acreage in tomatoes over the entire season,
WT = total water used on the farm, in acre inches,
IWA = average irrigation water applied per acre,
PWA = average precipitation received per acre, and
W = average total water use per acre of tomatoes, in acre inches.
The hypothetical data presented in Appendix Table 1 is used in the following
to illustrate the procedure. Given an assumption of pumps capable of
yielding 1,000 gallons per minute, Equation (1) becomes:
WI = (1/27,154) (1,000) [(25 x 435) + (25 x 470) + 25 x 520]
= 1,312 acre inches.
and for (2):
WP = (40 x 5.42) + (40 x 5.30) + (40 x 4.13)
= 594 acre inches.
Equations (5) and (6) give (as A = 120):
IWA = 1,312 = 10.9 acre inches
PWA = = 5.0 acre inches
Thus, the average total water use per acre by this hypothetical producer is
W = 10.9 + 5.0 = 15.9 acre inches.
This is the water use on a "typical" acre, as defined in this study. Note
that M. = 0 (no irrigation) during weeks where P. > 1.0 (for example, the
week of 12/6, Table 1).
 Carriker, Roy and Gary D. Lynne. "The Florida Water Resources Act of
1972: A Synopsis, University of Florida, IFAS, Water Resources
Council, WRC-10. Gainesville; 1978.
 Dalton, J. "Water Use Table by Crops." Homestead, Florida: Dade
County Cooperative Extension Department, March 1976.
 Florida Crop and Livestock Reporting Service. Florida Agricultural
Statistics -- Vegetable Summary, 1976. Orlando: March 1977.
 Florida Crop and Livestock Reporting Service. "Florida Cash Receipts
from Farming." Orlando: September 1977.
 Lynne, Gary D. and Kenneth C. Gibbs. Demand and Pricing Policy for
Residential Water. Food and Resource Economics Department,
Economics Report 83, Gainesville: University of Florida, December
 Lynne, Gary D. and Clyde Kiker. "Water Use in Southwest Florida: An
Economic Perspective." Food and Resource Economics Department,
Economics Report 82, Gainesville: University of Florida, November
 Lynne, Gary D. and William G. Luppold, and Clyde F. Kiker. Water De-
mand by Retail and Service Business Establishments, Dade and
Monroe Counties, Florida. University of Florida Agricultural
Experiment Station Technical Bulletin 800. Gainesville: 1978
 McGuire, John F. "Value of Agricultural Products in Dade County 1975-
76." Homestead, Florida: Dade County Coop. Ext. Dept., 1976.
 Pride, R. "Estimated Use of Water in Florida, 1970. U.S. Geological
Survey Info. Circ. 83. Tallahassee: 1973.
 Rogers, J.S. and George A. Marlowe, Jr. Water Needs of Florida
Vegetable Crops. University of Florida, IFAS, Water Resources
Council, WRC 2. Gainesville: 1977.
 South.Florida Water Management District. Water Use and Supply
Development Plan -- Executive Summary. West Palm Beach: April,
 Storch, W. "Water Management During Drought Events." In-Depth Re-
port, 2 (April 1974) West Palm Beach: Central and Southern
Florida Flood Control District.
 Williams, John H. "An Estimation of the Agricultural Demand for Water
in Dade County, Florida. University of Florida, 1976.