transpiration rate; it is only indirectly related to salts in the irriga-
tion water.
 Most of the salts added with the irrigation water are left
behind in the soil as water is removed by the crop. These may
accumulate and reduce the availability of water to future crops
and the overall productivity of the field. To dissolve and remove
the salts, adequate water must be applied to allow percolation
through the entire root zone (leaching). If water management
accomplishes sufficient leaching, saline irrigation water can be
tolerated to some extent.

PERMEABILITY
 A permeability problem occurs if the irrigation water does
not enter the soil rapidly enough to replenish moisture. This can
be directly related to unfavorable changes in soil chemistry as
caused by the quality of the irrigation water applied; the problem
is related to one of two causes -- either low salinity or high sodium
in the irrigation water.
 A corrosive liquid will tend to dissolve soluble materials on
contact. Low salinity waters are corrosive and tend to deplete
surface soils of the more rapidly soluble minerals and salts such
as those containing calcium. When such neutral soluble salts are
removed, the presence of sodium tends to dominate the system.
Sodium causes the dispersal (breaking apart) of soil particles.
These dispersed particles fill soil pore spaces, tending to seal the
soil surface by making it tight and impervious. This makes it
difficult for plant roots to penetrate and grow.

 High evapotranspiration rates on St. Croix cause concen-
tration of the soil solution with a tendency for less soluble com-
pounds to precipitate out. The carbonate forms of calcium and
magnesium are much less soluble than the sodium combinations,
and with their precipitation the proportion of sodium in direct
solution is increased. Sodium is the major problem with respect
to dispersal and soil structure as discussed above.

SOLUTIONS
 One of the biggest hindrances to the development of a
sound agricultural industry on St. Croix is the lack of water. The
rainfall pattern in recent years has been such that a vegetable
enterprise without supplemental irrigation would have faced
disaster. Unfortunately the potable water is too expensive, the
groundwater is limited in quantity and in many cases the sodium
and/or chloride content is too high for prolonged use. Under
special soil conditions, with certain crops and using careful irriga-
tion techniques, water with high dissolved solids can be used. The
fact that St. Croix has poorly drained soils combined with a high
evapotranspiration rate aggravates any attempt to irrigate with
waters of marginal quality.

 The situation for irrigation and water quality is not entirely
 bleak on St. Croix, however. With a SALINITY PROBLEM there
 are procedures to improve soil water availability to the crop.
 Some management practices include:
 irrigate more frequently to maintain a more adequate
 water supply for the crop;
 plant crops that are tolerant of an existing or potential
 salinity problem such as date palm, spinach, sugar and
 garden beets, and Bermuda grass;
 routinely use extra water to satisfy the leaching
 requirement;
 change the method of irrigation (i.e. sprinkler to drip)

 Since the PERMEABILITY PROBLEM only reduces the


MANY THANKS TO

THE DEPARTMENT

 OF AGRICULTURE

 Produced Daily On St. Croix
 From Six Purebred Dairy Herds


Grade A Fresh Milk
Non Fat Skim Milk
Fresh Whipping Cream
Chocolate Milk
Buttermilk
Sour Cream


Cottage Cheese
24 Ice Cream and
Sherbet Flavors
made fresh daily
Orange Juice


1 A tr island DaI ris Pr ducr a! avour local gro c'rv .str I,
(r stop at 17/II (G;O.n D '\ Co ( in Christiansted.


 ISLAND


 DAIRIES

 ST. CROIX, VIRGIN ISLAND