What is in this article?:
- Distribution uniformity an irrigation key
- Irrigation scheduling
- Even distribution of irrigation water can mean a combination of high tech wizardry and low tech, hands-on tweaking.
David Jamison, senior agronomist with PureSense in Fresno, uses a moisture probe to check how far into root zone water is seeping.
He said new technology enables the use of irrigation systems to better understand infiltration rates and to convert the number of hours used to the amount of applied water.
Irrigation scheduling draws on information from a variety of sources, including historical data and software that includes that provided through the university with its Wateright program.
Jamison said PureSense makes available a free software tool for irrigation scheduling. He said PureSense is not alone in providing help on distribution uniformity, noting there are private consultants and public agencies that can help.
All of the speakers said system maintenance is important, and that means filtration maintenance, checking for leaks and, flushing the system. Not doing so can mean lost money through inefficiencies in delivery of water or nutrients if a system is also used for fertigation.
Green explained that the highest pressure readings can be expected closest to the water source. Vang said guidelines from the Irrigation Training Research Center at California Polytechnic State University, San Luis Obispo are used to evaluate an irrigation system.
That’s where the goof plugs, pliers and other tools enter the picture. A punch is used to open a hole where a pressure gauge can be inserted. A reading is taken, adjustments are made and the gauge is withdrawn. Then a goof plug is inserted.
Vang and Green showed that measurements were taken at six locations -- near the water source, midway to the end of irrigation lines and furthest from the source. They found considerable variability in pounds per square inch at the different sites, as much as a 10 PSI difference in places.
They also showed how to check emitters to determine flow levels, using a bucket to catch water for two minutes and then pouring the water into a measuring container.
Jamison also talked briefly of developments in recent years to improve cherry production in the San Joaquin Valley where the number of chilling hours is critical.
He said some growers are using overhead evaporative cooling to boost the number of hours in order to gain a market advantage by encouraging earlier fruit production that can command a higher price.
Jamison said the past two cherry harvests in the Valley have been late, resulting in lower prices for many growers. He said it is important to take into account that warmer temperatures during the day can reverse effects of overnight chilling.
Cherries are not the only crop that can benefit from evaporative cooling. He said those measures are also being used in kiwis, applies and grapes.
Aric Olson, president of Jain Irrigation Inc., said his company has been using micro jets to cool vineyards in Napa Valley field trials for three years and is close to rolling out a new product for that.
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