Growers have many good reasons to invest in irrigation management. Water scarcity continues to be a pressing issue in the West, especially in years such as this one, when the snow pack in the mountains was far below normal. Water quality issues also continue to fester, principally in regions where vegetables are intensively produced, due to the loading of nutrients to ground and surface water supplies.
During the last decade, vegetable growers have made significant investments in drip irrigation to improve water use efficiency of their crops. But of equal importance, investments in personnel, decision support tools, and research are needed to meet the water management challenges that lie ahead in the upcoming decades.
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While many growers rely on advice from professional crop consultants for their pest and fertilizer management decisions, they less frequently seek out equivalent expertise for irrigation management. An experienced irrigation consultant can often pinpoint critical problems in the management of an irrigation system and propose economical solutions. Mobile irrigation labs can give a snap-shot assessment of the efficiency of an irrigation system and often determine how to improve the operation and design of the system. Investing in training of irrigation personnel can also pay off.
Irrigators need to understand the importance of their jobs, and learn new skills that will help them improve their effectiveness. Too often I find that the least trained workers on a farm are the irrigators. While they may be excellent at fixing leaks, moving pipe, and running pumps, they often lack the knowledge necessary for evaluating if an irrigation system is working properly and applying water uniformly to the crop.
Decision support tools are now becoming available to help growers fine-tune irrigations so that watering schedules better match the needs of the crop. A new generation of soil moisture sensors is easy to use and inexpensive, relative to costs a decade ago.
In addition, most of these sensors can interface with wireless systems to provide data to the end user through Internet-accessible devices such as smart phones and tablet computers. Flow meters have also improved in recent years, and can provide an accurate record of how much water is being applied to crops.
Several companies sell meters that use magnetic sensors that accurately measure flow, and because they have no moving parts, they break less often and stay calibrated better than traditional propeller meters. They also can be integrated into online monitoring systems so that the applied water of each irrigation is recorded and viewable from the web.
Estimates of crop evapotranspiration (ET) are also becoming more accessible to farmers. The California Irrigation Management Information System (CIMIS) provides daily reference ET data for more than 100 sites throughout the agriculture regions of California. Growers retrieve ET data from the CIMIS website (www.cimis.water.ca.gov) or sign up to receive email updates of the data for specific weather stations. For farms located far from a CIMIS station, there is also the option to use estimates of ET based on satellite data.
In addition, many companies now sell weather stations that estimate ET for those interested in determining ET on their ranch. Easy to use atmometers, which work like a reverse rain gauge by recording daily water evaporation, can be useful for determining how much water a crop needs.
To continue to make advances in water management of vegetables, investing in research also is needed. Genetic improvements in varieties may help growers use water more efficiently. Research currently being conducted by University of California-Davis and USDA Agriculture Research Service scientists is attempting to identify genes that increase drought tolerance in lettuce.
This research involves conducting field trials to screen varieties that are high yielding under water stressed conditions. The final goal is to develop parent lines that can be used by plant breeders to bring drought-tolerant traits into commercial varieties.
In summary, just as water management has become more critical to farming, more tools, technology, and services have emerged that can assist growers in becoming more efficient water managers. Other innovations
will likely be developed in the future, such as vegetable varieties that are drought tolerant.
Along with these technological developments, well trained personnel will be equally important for improving water management on the farm. Water management will likely remain a challenge for growers in the West, but with investments in personnel, technology, and research we can find economical solutions for improving water use efficiency of vegetables.