Geha Foods Evaluation of Irrigation for Processed Tomatoes

main river in the areas it becomes return flow and can be reallocated for irrigation and, since
there are no storage structures, down stream users may actually be highly dependent on this
return flow to meet their irrigation needs. In poorly drained soils, it can become a major
problem with water ponding in the fields long enough for anaerobic conditions to occur and
crops to suffocate as well as develop seepage areas and salt accumulations, etc. However, the
farms visited appeared to have sufficient deep drainage canals so it would not be a major
problem for the contract farmers. Typically it takes about 24 hours of ponded water for
anaerobic conditions to damage a crop. Tomatoes are one of the more sensitive crops to wet
feet.
% Maximum Yield
125
100
75
50
25
0
0 25 50 75 100 125 150
Well Drained
% Water Requirement
Impeded Drainage Paddy
Fig. 14. Schematic crop production function to applied water
Irrigation Promotions: It is interesting to note that most of the irrigation efficiency efforts in
the USA are not driven by agronomic yield increases, but by water as an economically
valuable and environmentally sensitive commodity. In the USA, with our very complex,
privately owned system of water rights, we have by necessity become obsessed with
measuring water. Water rights have highly paid lawyers specializing in water law and courts
dedicated to water rights litigation. Since we obtain water on a volume basis any water saving
has a direct economic return in terms of reduced production cost, and opportunity to “rent”
unused water to other users. It is also interesting that much of the shift away from siphon
tubes to gated pipe and center pivot irrigation system was driven more by increased labor cost
then need to conserve water. The water saving was a nice by-product. For over a century
Colorado irrigated at about 30% efficiency with no apparent detrimental impact on crop yield
or the environment and many people filing water rights on the tail water of other users.
In Tajikistan with what appears an ample water supply and not encumbered with the complex
water rights laws of the USA, the need to keep accurate account of water is greatly
diminished. With this will come less concern for irrigation efficiency. Thus, the emphasis on
irrigation management will rightly be making certain the crops ET needs are met, and little
more. Over irrigation will not be a major concern and one that the drainage canals should
readily handle. This limited need for highly sophisticated water accounting needs to be
carefully taken into consideration in evaluating how to assist farmers in improving their
irrigation for producing processing tomatoes and make certain there is a solid economic
return to the efforts, or a long term positive environment impact, and sustainable economic
return.
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