Evidence of the potential use of saline water for irrigation Rhoades J.D. in

Rhoades J.D.

in

Bouchet R. (ed.).

Reuse of low quality water for irrigation Bari : CIHEAM

Options Méditerranéennes : Série A. Séminaires Méditerranéens; n. 1 1989

pages 133-139

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--- Rhoades J.D . Eviden ce of th e poten tial u se of salin e water for irrigation . In : Bouchet R. (ed.).

Reuse of low quality water for irrigation. Bari : CIHEAM, 1989. p. 133-139 (Options Méditerranéennes : Série A. Séminaires Méditerranéens; n. 1)

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I Evidence of the potential I

use of saline water for irrigation

I James

Riverside Salinity Laboratory- UC Riverside - USA

in irrigated agriculture can occur in the near future because the readily available suitable lands and waters are fully developed ( U N World Food Conference, 1974). This author believes that this' conclusion is not entirely valid and that the

concept of suitability has been misapplied because of the conservative standurds used to assess the f i t n e s s o f w a t e r ( a n d l a n d ) f o r i r r i g a t i o n . Furthermore, only conventional criteria and procedures of producing crops under irrigation

have been considered in the evaluation of our future production capacity. Water commonly c l a s s i f i e d a s u n s u i t a b l e f o r i r r i g a t i o n b y c o n v e n t i o n a l m e t h o d s c a n o f t e n b e u s e d

successfully to grow crops without hazardous long- term consequences to crops or soils, even with the use of ordinary farming practices. The adoption of new croplwater management strategies will

further enhance the agricultural use of saline be expanded considerably through the implementation of certain strategies which allow greater use of more saline waters for irrigation. Considerable saline water, including drainage waters from irrigation projects and frequently associated shallow ground

waters, is available in many parts of the world, including the U S ,

Australia, and the

l n this paper, l present a n appropriate method for assessing the suitability of saline waters for irrigation, a brief review of relevant literature documenting the successful use of saline waters for irrigation, and the concept and summary results of a test of a new croplwater management strategy to facilitate the use of saline water for irrigation.

- Assessing the suitability of saline water for irrigation

The suitability of a

be evaluated on the basis of the specific conditions of use,

assessing the suitability of of:

1. composition

of the soil

2. of how

how

would of

1972).

A model

which uses

1976). A of it, called "watsuit", has also been developed and used to

- a of "watsuit"

(1987).

A of

1984). is accomplished using Table 1 and Figure 1, a s discussed

of

compositions A soil salinity

options

is deemed likely if the

of the

of will a yield

is a change in

in place of t h e no-

yield-loss of

by

(1977) (1986).

Example data given

in Figure 2.

The effect of of

(Le.

exists) is

uptake-weighted salinity" F, values of Table 1.

salinity F, values of Table 1

1 9 7 6 of changing the

index of of

To assess toxicity

specific used in

place of is used as

of

of t h e

topsoil of

- EC of 1982

details). The of the

is taken be t h a t of

of the soil at depth in the soil is if

of (1977) (1981).

Figure 1 can be used in lieu of Table 1

of conventional it

levels, of

be

of Table l of high of Table 1 Figure 1

is following example. Given

= 2 dSm-1 and a of 0.10 with conventional

salinity at steady-state is ECe = (1.88) (2) =

1.88 is

(F,) Table l.

to be is wheat with a

EC, of dSm-1 (Figure 2), t h e

is of

salinity is but 3.8 dSm-l. is

assess) s p e c i f i c s o l u t e as in the soil when they of

the effects of exchangeable sodium on by high

independently of soil

of a n

excessive ECiw

and The values in Figure estimates of the

soils. is

the

-

of Figure 3.

The slope of is below

values of 10 ECi, axis at a value of 0.3 because of the dominating effect of at such low s a l i n i t i e s . T h u s , e v e n a t l o w l e v e l s o f

soil of salt

subsequently used effects, techniques.

Toxicity seldom

they should be assessed as 1987).

- Evidence of the potential of using saline waters for irrigation

of

have concluded 1977) that the bulk of

in the US as well) have

potential value of

would of

disposal and as well.

options

Though of on the successful use of

conventional schemes of will

allow, can be of

of 1,500 mg/L of total dissolved solids and up

to 5,000 mg/L Valley,

1976). et al. (1978)

to 7.1 dSm-1 without effects on yield. gives a of examples of

of of

of up to 6,000 mg/L often classed as acceptable and indeed used.

(1966) concluded that the the salinity level of a n

is (1978)

4,000 mg/L without

(1975) (1978)

that cotton is

of 4.6

dSm-1. tJha yields of alfalfa

achieved in the with 12,500 mg/L of

good

of 5,000-6,000 mg/L total dissolved solids.

cited above, the successful use of of up to about dSm-1 (-6,000 mg/L) was noted. been claimed that

be 1967;

1977);

(1976) the

use of to 15 dSm-1

annual monsoons. et al. (1952) with salinities of up to 20,000 mg/L in the

only when a

stand establishment. These

be often

the

combined with indicate of

as suitable can be used finding implies that if a of the UN

Food

of

suitability if

a would

- A crop/water

management strategy to facilitate the use of saline.watex-s

irrigation

this section, a

of using is

of

et

al., 1988a, b). The impetus its

will if access to of salinity is available, unless significant losses in

signifcant changes of

The which meets

is to substitute the saline (such

the "good"

when they a suitably salt- stage; the "good" is used at

soil salinity in the use of

is used only a of the time. The timing and amount of substitution will

quality of the two

salt buildup in the

is alleviated in the subsequent

when a is

using the low-salinity

should be noted that a soil will not

become of a

a of a not

options

of

used to leach salts out of the seed and shallow soil depths. Subsequent "in season"

down in the ahead

of the advancing the

soil which

will be used a

This cyclic use of lllow't and "high" salinity

of a

a (50%) of the

This has i n a 20-

which was begun on a

a of

of wheat and of the melons.

Alamo

of The

a block of

two of cotton (a followed

by and

then by alfalfa (a

of cotton

with the wheat only

was used. was hypothesized that wheat would

d e s a l i n a t i o n of

alfalfa to of yield.

The yields of the in the successive -and block - given in Tables 2 and

No significant losses in the yields of

cycle of

(even CA

65-75%)

establishment. The mean yield of cantaloupe seed obtained in the CA

statistically significant. The yields of

melons of of cantaloupe

obtained by

in the Ca and CA in the C

Table 2).

cantaloupes using of wheat The yields of

Table

lint yield of

when it

A). no significant loss in lint yield in the second cotton use of

following seedling establishment which was accomplished

CA). But was a significant and substantial loss of lint yield, a s expected,

used

A). This loss of yield was caused by a loss of stand that in the second

in the seedbed No loss in yield of

in the block the

of

The qualities of all of

or on the i t

et al., 1988a).

of

and given

i n Tables 4 a n d 5

-

block - data include

data show that substantial amounts of

of loss.

The estimated amounts of by the as deep given i n T a b l e 6 by individual

by succession of

was assumed that consumptive use was the no substantial losses of

leaching.

on soil

et al., 198813).

of the when the

of the facilitate the use of

- Blending drainage waters for reuse or discharge

is not uncommon to to expand by

too saline use by

to obtain a of the mixed

t h a t is blending is

1 9 8 8 ~ ) . T h e following logic is applied. A plant

must (that would

used to

a saline (low osmotic potential) soil solution.

When a of

is mixed with a low-salinity

"good of the mix made up of the excessively

is left. is still as unusable

of view) as it was

point without excessive yield loss. Thus, a of the low-salinity (fully

as a consequence of blending.

Thus diluting excessively less

of

is only usable by

indicated that, any succession of of

of high salinity) available is

by:

EC, 1 -

ECb

EC

a, and the efficiencies needed a

of EC = 1.0 dSm-1, of

1/45 to 1/15 would be the most salt- With such effkiencies, 67% of

the most sensitive would

the most of such saline

to a common t h a t

supply of sensitive

The above estimate of of

is based on the assumption of steady-state conditions and use

of of

will not be of

sequentially with it. a is so saline that its

use is

diluting it with

of of the same or

in this of mixing, simply mixed the usable which must be by the plant. The

if the two used cyclically as

show that a loss i n of a

a good 1 9 8 8 ~ ) .

options

V - Conclusion and summary

of now

conventional methods of

of good of low salinity

of low

typically classified a s good

documents the successful use that can be made of

of of

of

be enhanced if a modified dual of management is used. The objective is to substitute the saline

of

yield loss

or

For

low

The feasibility of by

J.W. Wadleigh, 1952. Salt

of

salinization J., No. 44, pp. 307-310.

1979. The use of saline in

the Joint Commission on Scientific and Technical

L., 1966. of

to of

No. 10, pp. 185-189.

1967. Sci.

(31, pp. 89-96.

1976. of highly saline

conditions in soil a cyclic

Lubbock: Texas Tech. Aug. 1976, pp.

608-609.

Espstein, E.

A feasibility :Sci., No. 197, pp. 247-261.

~.

and 1975.

Chemical soil

cotton -

Symp., pp. 175-183.

A., 1976.

conditions. Salinity

Tech. Aug.

1976,pp.165-169.

Stolzy, 1978. Use of

(51, pp. 169-192.

and

i t s effect on the soil and on cotton fields.

No. 58, pp. 963-976.

E.V. and G.J. salt

Evaluation of existing data. Salinity Lubbock TexasTech. Aug. 1976, pp. 187-198.

E.V., 1986. of plants.

1 ( l ) , pp. 12-26.

-

1977. Valley of

C.O., 8 0 p.

J. and J.V.

the Valley of West Texas. 2 Salinity

Lubbock: Texas Tech.

Aug. 1976,pp. 339-344.

evaluating the effective salinity and sodicity of

Salinity Lubbock Texas Tech.

Aug. 1976, pp. 1-14.

X.J., 1972. with saline New 198p.

A.F. and Salinity

and management in No.

pp.

Quality of for Soil Sci., No. pp.

for using

for Water

and Nevada, July

pp.

for

a to salt loading of

lnt'l Symp., State-of-the-Art Control Salinity. Utah: Salt Lake City, July

for

America. Venezuela, Oct. pp.

Also published in Scientific review on arid zone, Vol. :

New for using

for Spec.

Conference, Water Today and Tomorrow, July Flagstaff, AZ.

Use of for

Nat'l

Water Quality Bulletin, No. pp.

of for

supplies. Agri.

and Assessing the

suitability of for

of Salinity and Alkalinity. FAO Soil

J. Letey, G.J. W .J. Alves, Swain,

and of drainage water for

irrigation Hilgardia (in

F.T. J. Letey,

W.J. A1ves;G.J. J.A.

Swain and 1988b. o f drainage water

for irrigation: Soil

balance. Hilgardin (in Shalhevet, J. and J.

salinity: a l n t 7 C o m m i s s i o n o n p.

and sodium of estimating of soil or Soil Sci. Soc.

Ameri. J., No. pp.

UN Food Assessment ofthe World

Nov.

options méditerranéennes

Table 1: Relative concentration or electrical conductivity of soil water (saturation paste extract basis) at steady-state compared to that of irrigation water (Fc)

Rootzone interval 0.05 0.1 o 0.20 0.30 0.40 0.50

- - - _ _ _ _ _ - - _ _ _ _ _ - - _ - _ _ - _ _ _ _ _ _ _ _ _ _ _ _ - - - _ - - _ - _ - _ _ _

Linear average (1)

Upper quarter 0.65 0.64 O. 62 0.60 ^{, 0.58} 0.56

Whole rootzone 2.79 1.88 1.29 1 .O3 0.87 0.77

Water uptake weighted (2)

Whole rootzone 1.79 1.35 1 .O3 0.87 0.77 0.70

(1) Use for conventional irrigation management.

(2) Use for high frequency irrigation management or where matric potential development between irrigations is insignificant.

Table 2: Yields of crops in successive rotation

I

C r o p y e a r

sugar sugar

Treatment Wheat/l982 Beets/l983 Cantaloupes/l983 Wwheatll984 BeetSA985 Cantaloupes/l985

1 ) 4 ) 3 )

2 )

3 ) 5 )

I I

C 3.60 (0.06) ' l ' 4.3 (0.1) 392 (1 2) 3.51 (0.09) 4.1 (0.1) 115 (5)

3.60 4.3 (0.2) 384 (10) 3.46 (0.10) 4.1 (0.1) . 142 ( 8 )

CA 3.71 (0.06) 4.1 (0.1) 355 (1 4) 3.55 (0.09) 3.9 (0.1) 139 (12) 1) C = Colorado River water used solely for irrigation; Alamo River water used in relatively smaller (Ca) and

larger (CA) amounts, after seedling establishments with Colorado River water for wheat and sugar beets.

Cantaloups only irrigated with Colorado River water.

2) Tons grain per acre 3) Tons of sugar per acre 4) Lbs. of seed per acre

Commercial yield in numbers of cartons per plot;

6) '-Value within ( ) is standard error of mean; six replicates plot size = 750 X 38 feet = 0.6543 acres

.

Table 3: Yields of crops in block rotation

Crop year

Treatment Cotton/l982 Cotton/l983 Wheat11 984 A l f a I f a i l 9 %

1 ) 2 ) 4 ) 3 )

C 2.62 (0.07) 2.06 (0.10) 3.43 (0.06) 7.8 (0.4)

CA 2.65 (0.06) 2.00 (0.06) 3.43 (0.06) 7.0 (0.5)

A 2.76 (0.04) 1.32 (0.05) 3.41 (0.05) 7.4 (0.3)

1) C = Colorado River water used solely for irrigation; A = Alamo River used solely for irrigation; CA = Alamo River water used for irrigation after seedling

establishment with Colorado River water for cotton. Wheat and alfalfa irrigated only with Colorado River water

2) Commercial yield of lint, bales per acre 3) Tons of grain per acre

4) Tons of dry hay per acre

5) Value within ( ) is standard error of mean; six replicates

options

O

ü

5

S

O O 2

- S

S

O

c o m a

C U C U C U

c o c o w

e n - Y V W

m - o

c 3

9 8 %

a m * ^od-CD

n t - 0

N N O

n - &

N o 0

n d - o

O

- 5

S

ò

S

O

' 8 %

S

E S

r- r - a

7

D O O

.- ^C

- E

Table Estimated evapotranspiration and water lost as deep percolation (inches 1

Accumulated (5)

Crop

v

et iw dw i w e t dw

wheat S. beet

melons wheat S. beet melons

cotton cotton wheat alfalfa

Successive crop rotation

Block rotation

Evapotranspiration estimated from pan evaporation and crop factors at Brawley, California Total amount of water applied for irrigation

Estimate of deep-percolation ,drainage water, i.e., Vi.\;

-

(4) Estimate of leaching fraction, i.e., Vd, 'Vi, Accumulated over entire experimental period

options méditerranéennes

Figure l ^8: between average rootzone salinity (saturation extract basis), electrical conductivity of irrigation water, and leaching fraction to use

for conditions of conventional irrigation management

o r .

c

O 4 6 . 8 10 12

Elixfrical Conductivity 01 Irrigation Wafer, dS/m

Figure 2: Salt tolerance of grain crops (after 1977)

5 15 25 . 30 35

Millimhos/Cm

Figure 3: Threshold values of sodium adsorption ratio of topsoil and electrical conductivity of infiltrating water for maintenance of permeability

Areo of unlikely permeability hazard

Electrical Conductivity of Infiltrating Water, dS/m