Deep Pipe Irrigation
By David A. Bainbridge
Associate Professor
United States International College of Business
Alliant International University
San Diego, CA 92131
Using a pipe, bamboo with the internal nodes punched out, or a bundle of
straw or sticks to place irrigation water in the deep root zone is very
effective and well suited for gardens, small farms, and remote landscaping
and forestry projects. Deep pipe irrigation is commonly done with 1"
to 3" diameter vertical pipe placed 12-18" deep into the soil
under or near the crop plant or tree. The top of the pipe should be
covered with a cap or a screen disk. For large scale ecological
restoration work we glue 1/8 inch galvanized screen disks to the top of
the pipe with silicone caulk.
A series of small holes should be drilled in the side of the pipe near the
plant if a seed is used or if a small transplant with roots shorter than
the pipe is planted. The seed or seedling should be fairly close to the
pipe (1-3 inches for a young plant). Several pipes are used for a full
grown tree. These can be arranged to encourage root growth to resist
windthrow and minimize interference with inter-planted crops.
These may be filled with water bottles placed in the pipe (observed in
Kenya), filled with water from a water truck or hose, or fitted with a
drip emitter. If a drip system can be setup the pipe can be smaller
diameter (1/2"). We have set up a deep pipe irrigation system on a
remote tank with battery powered timer to irrigate once a week with
excellent success.
Deep pipe irrigation is better than surface or buried
drip systems in several respects. First, it can be used with low
quality water and low technology. Second, even in areas where the
materials and technology for drip systems are available the deep
pipe system provides the benefits of buried drip, greater water use
efficiency (due to reduced evaporation) and weed control; but the
surface mounted deep delivery drip systems can be monitored and
repaired much more easily. And, finally, the pipes can be collected
at the end of the season for full field tillage operations to any
depth desired. |
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Experiments in Africa and San Diego county have demonstrated that deep
pipe systems are much more efficient than surface drip or conventional
surface irrigation. Deep pipe irrigation develops a much larger effective
rooting volume and plants better adapted to survive on their own. Survival
of trees on deep pipes in the California desert has been excellent after
modest irrigation (a total of a few gallons over the first two years)
compared to total failure of surface irrigated trees given the same amount
of water. After five years tree survival was excellent, and some trees
were 15 feet tall.
Deep pipe irrigation can be especially useful on slopes and in crusty
soils where surface applied water will run off. It increases the ease of
watering remote sites and has been very effective in land restoration
projects. It should be much more widely used!
Further Reading:
Bainbridge, D.A., M. Fidelibus and R. MacAller. 1995. Techniques for
plant
establishment in arid ecosystems. Restoration and
Management Notes
13(2):198-202
Bainbridge, D.A., Robert MacAller, M. Fidelibus, R. Franson, L. Lippitt,
and A.C.
Williams. 1995. A Beginners Guide to Desert
Restoration. National Park Service,
Denver, CO 34 pages.
Sawaf, H.M. 1980. Attempts to improve the supplementary irrigation systems
in
orchards in some arid zones according to the root
distribution patterns of fruit
trees. In: Rainfed Agriculture in the Near East
and North Africa. FAO, Rome,
Italy pp. 252-259
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