Geha Foods Evaluation of Irrigation for Processed Tomatoes

Once the water is more concentrated for easier irrigation and the fields have been graded, it
would be possible to consider some more controlled means of assuring a uniform application
of water to each furrow instead of the current cut from the head ditch with a targeted
discharge of 1 l/s/furrow. In the USA this was historically done with siphon tubes that have
recently given way to gated pipe. In Tajikistan it might be possible to make adaptation of
some materials that appear readily available. This would be the trapezoidal pre-cast concrete
canal material that is used extensively around the country including some of the irrigation
canals to move surface water around (Fig. 17). If these could be lined up on the dead level,
simple gated outlet structures could be cut near the top at intervals equal to furrow widths.
Then with simple check structures in the canals, it would be possible to raise the water level
in the concrete gated canal above the ports and allow water to enter each furrow. Similarly,
removing the check structure would allow water to drop below the ports and down to another
reach. If dead level and with reaches of appropriate size, a uniform flow of water would enter
each furrow and proceed uniformly down the furrows and reach the end at nearly the same
time. The target application should be 1 l/s/furrow. Again Geha Foods agriculture support
service could be of assistance to the farms by providing credit and assisting in the installation
of the gated canals.
Fig. 17. Prefabricated canals commonly used in Tajikistan for
moving surface water that have the potential to be used for gated
head ditches by installing ports near the top of the section. The
example is approximately 60 cm across the top as shown by the
individual hand being at 1 m.
Overall Water Management: The overall water management of the farms will be somewhat
more difficult to obtain as it has to integrate the needs of all the different crops and fields into
a master plan of some kind that may need to be adjusted on an annual basis depending on the
revolving mix of crops. It would be nice if the farm could be blocked into 14 nearly uniform
field plots and rotate the water on a weekly basis as described in the conceptual example from
Colorado. However, an established surface irrigation system has well established canals and
drains that can not be easily changed. Thus any irrigation plan has to accept the land units as
they are and block them as best they can for easy within farm rotations.
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