Regulations, falling aquifers and water restrictions alter irrigation practices.
I fondly recall the coolness of the water flowing down the ditch on my father’s farm when I was a youngster. The V-notch ditch was filled with water pumped from the Ogallala aquifer under the High Plains of Texas, and we had a seemingly endless supply.
Playing in the irrigation ditch is an activity that is long gone on the Texas farm in 2012. Changes in water laws, falling aquifer levels, water production restrictions and commodity production input costs have all worked to curtail the use of less efficient methods of irrigation. These factors have had the same net effect in all the major irrigation centers of the U.S. V-notch ditches gave way to underground piping systems with gated pipe. These are now morphing into subsurface drip and mechanized irrigation methods, such as pivot irrigation.
Above: Flood irrigation on date palms by a vertical turbine pump, circa 1952, California
Left: Pivot irrigation from a pump’s point of view
Irrigation Methods
Total irrigated acres in the U.S. hover near the 56.5-million-acre mark with flood, sprinkler and drip irrigation methods accounting for 22.0, 30.8 and 3.7 million acres respectively according to the U.S. Department of Agriculture (USDA) Census of Agriculture. Mechanized and sub-surface irrigation methods can save up to 50 percent of the water used given the same set of commodity production circumstances. Pivot irrigation exploded in popularity in the mid 1980s, reflecting one of the first significant changes in the efficiency evolution. Sub-surface irrigation accounts for 3.7 million acres, showing a 28-percent increase in acres from 2003 to 2008. Pivot irrigation grew 20 percent during the same period.
Economic forces have an undeniable effect on farm irrigation practices, but other forces (water laws and global population growth to list a couple) are becoming equally important. As a result, American farmers find themselves at a crossroads. The pressures of production costs, water laws and global population growth are driving increasing demand for commodities. Therefore, these economic realities have created an environment for change in technique and technology.
Facts and Statistics
Some interesting statistical and demographic data give us a glimpse of changes to come on the American farm and for global agriculture. A widely accepted statistic is that 70 percent of all the fresh water used in the world is used for agricultural irrigation. Many of the major aquifers, the Ogallala or the San Joaquin for example, are in decline as aquifer recharge is outpaced by the withdrawal rate.
The total number of farms in the last 30 years has decreased 28 percent. During this same timeframe, the total acres in production have decreased by only 14 percent. The data from 1978 to 2007 indicates that two farm categories are increasing, farms in excess of 2,000 acres and farms smaller than 50 acres. Mid-sized family farms are being consolidated into larger farms. Small hobby farms are increasing in number. However, the total revenue provided by those farms is almost inconsequential when compared to total U.S. commodity production. Many of today’s younger farmers are better educated than past generations and are more accepting of new technology than previous generations.
Ninety-nine percent of all farmers use mobile phones and 87 percent are connected to the Internet. This level of connectivity is driving new trends in irrigation. Many companies are developing new, remote monitoring technologies and linking pump systems and other salient soil and wind variables together to eliminate inefficient irrigation practices. Technology that is routine in industrial and municipal settings is not widely adopted on the farm due to the distances covered for data collection and transmission.
New sensor technology is being linked to small weather stations integrated into irrigation systems. These weather stations can be linked to sub-surface moisture devices and wind speed indicators to recommend start and stop functions associated with the irrigation system when conditions fall out of limits. Inclusion of variable frequency drives (VFD) on traditional irrigations systems has proven to lower the electrical demand by 22 percent without addressing the inefficient pumping equipment that may be present. Adoption, development and deployment of these technologies on the farm have been slower than in other industries.
Future Irrigation Systems
The recent past has ushered in a new attitude of stewardship toward our underground resources. Most experts predict the irrigation system of the future to be a fully-integrated package that includes:
Pump controls and monitoring
Weather and soil sensors
Water quality chemigation/fertigation analysis and injection
Irrigation delivery system that compensates for soil type and elevation changes
At a recent meeting of irrigation technology and equipment providers, no consensus could be found for standard protocols for network connectivity and data transfer. The arguments presented hearken back to the days of VHS versus Beta. Clearly, both technologies were eclipsed by the development of a video disk. Those who are early adopters of the eventual industry standard will assume the position of market leader.
Currently, no commercially viable systems are available that integrate all the available information that is needed to efficiently manage the large corporate farming operation from a central location. Advanced pump controls coupled with VFDs could help deliver constant pressure through the system and compensate for elevation while giving producers the ability to monitor the health and operation of the pumping system. Amp draw, vibration and flow measurements could provide early warnings and allow the farm to proactively remedy the system prior to an outright pump failure. Water quality analysis, in addition to chemigation/fertigation dosing technology can deliver micro nutrients and pesticides at the time of crop maturity and or pest infestation. All these components would have the ability to be remotely monitored.
The tallest hurdle to clear in the quest for system integration and irrigation efficiency is how to compensate for soil types, irregular field shapes and soil moisture variations along the span of the mechanized irrigation system or subsurface system. These variables add the most complexity to current systems in development and future solutions.
Uniform application and timing of the water will produce a more consistent and predictable crop yield and drive more efficient resource usage. Aerial photographs demonstrate the application variation that may not be visible from the ground. Pivots often stretch more than a half mile in diameter. The variation in soil type, elevation and field saturation levels are virtually limitless. Controlling and adapting irrigation rates on the fly, in real time is a complex task. A fully-integrated system that is reliable, robust and adaptable is somewhere on the horizon. Economic pressures, commodity demand and resource scarcity will accelerate a system’s development that creates value for all participants.
As newer technology evolves, farmers may one day remotely conduct multiple tasks, such as:
Verify the operation of all components involved in multiple irrigation systems.
Verify soil moisture and wind speed at each location.
Increase the injection rate of the fertigation system.
Stop, start or reverse the system.
Adjust the operation of the system based on future weather forecast.
Flexibility and control will be possible from a laptop or smart phone.
P&S