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International High Tunnel Designs
Photos courtesy of Gary Hickman |
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| Egypt |
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High
tunnel production in Egypt occurs in both winter and
summer. This typical high tunnel is 9 m (29.5ft) X 40 m
(131ft) on sandy soil in reclaimed areas. Structures are used
for production of drip-irrigated tomato, cucumber, eggplant, and pepper (as
shown at left.) Over 15,000 high tunnels are now
under production in Egypt. |
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| El
Salvador |
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This
12 m (39ft) X 6 m (20ft) high tunnel structure in El Salvador is supported
by bamboo posts. One-inch PVC forms the sidewall and roof supports. |
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The
structure is covered with 6-mil UV-stabilized polyethylene.
Twenty-liter plastic bags filled with local sawdust waste and
sand will be used as growing media. |
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| Mexico |
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Although there are many high tunnel operations in the
state of Sinaloa, Mexico, this one operation has 375 hectares (925 acres)
of high tunnels. They grow primarily beefsteak tomatoes, but
also produce seedless cucumbers and bell peppers. It is the largest
single complex of high tunnels in North America.
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The
metal structures are 106 meters long, 30 meters wide and 5
meters tall. The sidewalls and endwalls are covered with insect
netting and the roof is polyethylene. No heating, misting or fans are used.
Freezing temperatures here are very infrequent |
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| Mongolia |
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A
very inexpensive high tunnel made of two-by-four and scrap lumber
in Mongolia is covered with polyethylene. The wood wall on the
left is a snow wall, to hold back Siberian winds and snow. One
problem is the lack of ventilation; however, with this area
experiencing extreme cold, the grower is reluctant to add vents.
Cucumbers are being grown in this tunnel and growers are learning
how to string the crop for support. |
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| Nicaragua |
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These
tunnels in Nicaragua are 2 m (6.7 ft) in height. The sides are covered
with insect netting and the roof with UV-stabilized polyethylene.
The ends, or doors, are simply plastic sheets that can be pulled
together and tied off. Tomatoes are being produced in these
tunnels. |
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Tajikistan |
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With no electricity or heat for most of the day in the rural
areas in Khujand, Tajikistan, these poly high tunnels are built into the ground.
Two meters of soil are dug out, then a 1 meter tall roof is
added from
the soil level up. The tunnels are oriented with the long side facing
south. The plastic roof is covered with straw and a layer of
poly each night which is removed the next morning. The wooden
structures are 8 m x 50 m.
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The
main crops grown are lemons, mandarins, cucumbers and tomatoes. The
citrus crops looked good, the tomatoes were newly transplanted,
and the cucumbers were not doing well. Heat absorption during
the day provides adequate night time temperatures. The average
night temperatures in winter are in the 0 to -4 C range. |
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| Uzbekistan |
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The
design of these high tunnels in Uzbekistan show hoops constructed
of re-bar which support the polyethylene covering. The poly
can be vented at the ridge.
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Roof
vents have been cut in the polyethylene to allow heat and humidity
to escape. |
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End
vents accommodate air flow into and through the high tunnel
structures. |
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| Gary
W. Hickman is a Horticultural Consultant for US-AID projects.
For more information, see www.cuestaroble.com |
