Geha Foods Evaluation of Irrigation for Processed Tomatoes

Too often the interpretation is either “a” or “b”, lack of knowledge or lack of concern.
However, more often than not, in this consultant experience, it has been “c” lack of means,
and the emphasis on “a” and “b” at the expense of “c” has been major reason for the limited
effectiveness of total agriculture development effort over the past 40 years. How you
approach improving the irrigation system or other agriculture activity varies tremendously
depending on which of these choices is assumed and which is actually correct. In the first
two cases the need is to emphasize knowledge, education and motivation, while in the latest
case it is facilitation and enhancing the resources available to the farmers to do what they
already knows needs to be done. Mistaking “a” and “b” for “c” can not only result in an
ineffective effort, but can be somewhat antagonistic to sensitive recipients as it implies
considerably less competence than they may actually posses.
When the farm chairmen in the last field visit could accurately tell the elevation drop down
the furrows and acknowledge the importance of leveling, but claim that it has not been done
since Soviet time, I think “lack of means” could be the major problem. Certainly, if he is
leveraged to produce cotton with uneconomic returns, the lack of means to fully maintain the
on-farm irrigation system is very real. It has to be a legitimate second priority to wages for
the farm families. If this is the case, Geha Foods can provide some valued assistance to the
farms by working with the various chairmen and implementing irrigation improvements as
fields are rotated into tomato production, and mostly following the desires of the farm
chairman for what he sees as needing to be done. From the political perspective of obtaining
the cooperation needed for tomato production, it is really the only option.
Brief Description Irrigation in Tajikistan
Field Applications: The current irrigation system in Tajikistan is a surface system that
appears developed primarily for large State Farms, with their excessive labor supply. It thus
appears more like the systems I have seen serving smallholder communities than those
serving large farms. This has resulted in the water flows that appear subdivided to the extent
the water can be manually shifted to individual furrows or small groups of furrows (Fig. 5),
rather then large 20 ha surface irrigation sets common in Eastern Colorado. Such limited
flows result in substantial conveyance losses in the system most of which will leach to the
water table and eventually return to the rivers. Also, the irrigation furrows tend to run
directly down the slopes instead of along the contour with slopes of up to an estimated 3%
(Fig. 6). This is too steep of non-critical (laminar) flow resulting in turbulent flow and
noticeable erosion in the furrows, some of it approaching 30 cm of erosive cut. To some
extent the erosion is minimized by allowing very low flows to enter the furrow, perhaps as
low as 0.25 l/s instead of the 1 l/s or more usually needed to push a wetting front expediently
to the end of a furrow. Furthermore, the furrows are not uniform in grade and will have one
or two benches down the furrow that will slow the flow, deposit some suspended sediment,
and possibly breech between furrows, before continuing to the end of the furrow (Fig. 7).
The actual flows into the individual furrows are often insufficient to reach the end and the
irrigation physically stalls, preventing the lower end from receiving any water. Irrigation
stalls occur because as water flows down a furrow or basin the wetted surface continually
increases as does the rate of water infiltration (Fig. 7). If the rate of infiltration exceeds the
rate water enters the furrow no further advance is possible and the irrigation stalls. It also
results in increasing the opportunity time for water to infiltrate and thus increases the
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