Geha Foods Evaluation of Irrigation for Processed Tomatoes

instead of normal square fields. Modern system can have sufficient computer controls to
make adjustments for the two crops when necessary. They will require a continuous 7 day 24
hour water supply of some 70 l/sec. This represents considerable consolidation of the current
water delivery and may require some tough negotiations to obtain, but should be doable.
Organization
Organizationally from an agriculture support services perspective this would be more
difficult to organize as center pivots are permanent installations that can only benefit the land
on which they are installed and not be shared between farms as the laser leveling equipment
can. It thus represents a major capital investment in one farm that needs a secure mechanism
for recovery. They certainly should not be provided free.
Managerial Flexibility
Center pivots do not provide a lot of flexibility in water management. You normally get a
fixed irrigation application which each circle. Pivots can be speeded up to apply less water
and slowed down for more water but within limits of the 24 hour rotation. Also, pressure can
be adjusted to increase or decrease the water, if the water source will allow it. However,
frequently they simply move continuously around the circle, 24 hours a day 7 days a week.
Often when the water supply is limited, such as from a well with declining water yield they
have difficulty keeping up with the ET demand, and actually need some supplemental rainfall
to catch up with the demand or the crop will slowly become progressively more stressed. For
this reason they tend to operate through any showers or thunderstorms, etc. They are
mechanical devises and subject to normal mechanical maintenance particularly with the
gearboxes for each tower and occasionally getting stuck in the mud. They can be advanced
to line up with the fields and allow easy access to the crop for mechanical operations.
However, they still are the most cost effective and reliable irrigation system, at least in the
USA.
Following up on this possibility would best be done by contacting a company representative
for more formal discussion with careful concern for disease control and what can be done to
minimize it.
Overview
Drip Irrigation for Tomatoes
Drip is perhaps the most heavily promoted form of irrigation, particularly by those who do
not have to pay for it, operate it or maintain it, such as our SIDA friends who insisted on it
but did not know what an emitter was, and how easily they can become plugged. It is also
the most expensive, sensitive, and complex to manage, with high reoccurring and
replacement costs as well as the specific mandate of this consultancy. The heavy promotion
of drip irrigation is mostly due to its potential to reduce water use. However, its effectiveness
in saving water can only be done, if and only if, the minimum application by alternative
means, such as sprinkler and surface, is greater that the crop water needs. Thus it can
become important in incomplete canopy crops such as vegetables, but not necessarily process
tomatoes for which the vines tend to fill the canopy. The effectiveness of drip is based on
reducing the soil evaporation component of the evapotranspiration water loss, while not
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