Making the Most of Water

Gravity-driven drip irrigation designed for underdeveloped areas

By Jane Moorman

Raising a garden to supplement a family’s diet is tedious work in the desolate areas of Navajo Country in the Four Corners region of New Mexico. Water has to be hauled many miles in a tank in the pickup truck’s bed or in a tank trailer and then distributed to the plants via buckets carried by the gardener.

Researchers at the New Mexico State University Agricultural Science Center south of Farmington are working with an economical system that can be used anywhere. It can save on manpower and deliver the water efficiently through drip irrigation. Dan Smeal, college professor at the science center who has gathered data regarding efficiency of various forms of irrigation, is now testing a system developed in India.

“It is so simple, I wonder why I didn’t think of it before,” Smeal said. The gravitydriven system requires a reservoir six feet above ground level, distribution pipe and emitters, all of which can be very basic or extravagant depending on the amount of funds available.

“This system was created for farms with limited water resources in underdeveloped countries, such as Africa and India, to help them grow crops in an efficient way. People wishing to raise a garden in the remote areas of the Navajo Reservation face similar conditions,” he said.

From a 55-gallon drum mounted on a 5-foot-rack, water flows through one-inch diameter poly-pipe to half-inch irrigation tape to microtube emitters that deliver the water to the individual plants.

“The system can also run from a fivegallon bucket with a simple filtering system, such as cheese cloth, but the reservoir has to be filled more often,” Smeal said of a system that he used in a demonstration plot last year. “We had to fill the bucket seven times each day to water 85 plants.”

This year, with the assistance of research technician Joe Ward, Smeal is gathering data from a third-of-an-acre plot where they are growing tomatoes, chile and corn.

“We are using three irrigation levels where we are watering at 50, 75 and 100 percent of a reference evapotranspiration value which represents the atmospheric water demands of the crop depending on the solar radiation, temperature, relative humidity and wind speed. The hotter, drier and windier it is the more water it’s going to take to fulfill the plant’s needs,” he said. “We are weighing the produce to determine the yield rate at each level of watering.”

For anyone gardening without a water source close at hand, Smeal said this system will allow them to fill the reservoir once a day and gravity will do the rest to deliver the water to the plants. “We have had one lady tell us she plans to install this system next year. Presently she is watering from an artesian well but has to spend a good portion of the day hoeing paths for the water to each plant. She works for the school district and when school starts she is unable to water her garden, so her plants suffer and the produce yield decreases. This system will allow her garden to produce later into the season.”