Increased Demand for Water Calls for Greater Efficiency
Save Water. Save Labor.
What trends will shape the future of agriculture, and how will they affect the demand for irrigation water? Every type of irrigation used has both benefits and drawbacks. However, the superior efficiency of mechanized (pivots and linears) gives it a clear edge.
More water used by crop.
The concept behind irrigation efficiency is simple – deliver the required water to plants, when they need it. By that standard, surface irrigation is the most wasteful method, with only 40
percent to 50 percent efficiency. Drip sets the standard
at just below 100 percent, but mechanized is only slightly
less efficient at 98 percent when using LEPA. However,
because water flow cannot be seen with drip, there may
be a tendency to over water.
percent to 50 percent efficiency. Drip sets the standard
at just below 100 percent, but mechanized is only slightly
less efficient at 98 percent when using LEPA. However,
because water flow cannot be seen with drip, there may
be a tendency to over water.
Reduced installation costs.
Installation costs for subsurface drip systems generally are 50 percent to 100 percent greater than for mechanized on relatively large fields.12 The efficiency of the system is highly dependent on the skill of the irrigation technician who designs and installs it. Mechanized systems, by contrast, can easily
be moved among fields and installed for consistent
performance.
be moved among fields and installed for consistent
performance.
Lower maintenance costs.
The annual maintenance
expenses for an mechanized system typically are less
than 1 percent of the original purchase price. Maintenance
costs for subsurface drip average between 3 percent and 10 percent of the purchase cost per year. If the system is not routinely maintained, efficiency can quickly deteriorate because of plugging, root intrusion and pest damage.
expenses for an mechanized system typically are less
than 1 percent of the original purchase price. Maintenance
costs for subsurface drip average between 3 percent and 10 percent of the purchase cost per year. If the system is not routinely maintained, efficiency can quickly deteriorate because of plugging, root intrusion and pest damage.
Automated controls.
Computerized monitoring and control systems can ensure that mechanized equipment operates at peak efficiency. Automated controls maintain the correct relationship among soil type, water-holding capacity, crop water demands, equipment speed and sprinkler package design.
Energy savings.
The rising cost of energy is a concern for every grower. The low operating pressure of modern irrigation systems, such as mechanized, makes them far more energy-efficient than older technology, such as surface irrigation, which requires far more
water. Mechanized also operates at lower pressures than
solid set and wheel-line irrigation, which reduces energy costs.
water. Mechanized also operates at lower pressures than
solid set and wheel-line irrigation, which reduces energy costs.
Increased longevity and resale value.
When properly maintained, mechanized systems can perform
efficiently for up to 30 years, compared with an average
of 10 years for drip systems. Because mechanized systems
can be moved to another field, they hold at least
50 percent of their resale value for up to 15 years. By
contrast, growers replacing a drip system must dispose
of worthless used tape in an environmentally sound way.
efficiently for up to 30 years, compared with an average
of 10 years for drip systems. Because mechanized systems
can be moved to another field, they hold at least
50 percent of their resale value for up to 15 years. By
contrast, growers replacing a drip system must dispose
of worthless used tape in an environmentally sound way.
Reduced salinity.
Water logging associated with surface irrigation increases soil salinity, which can reduce both yields and land value. The western part of the Central Valley, where 57 railroad cars of salt from irrigation water and other sources are added to the soil daily, is a major area of concern in the state. Although both mechanized and drip irrigation address this problem,
salinity can build up where wet and dry soil meet in
drip-irrigated fields. The capillary action of the upward
movement of water in drip systems also can move salt
into the root zone.
salinity can build up where wet and dry soil meet in
drip-irrigated fields. The capillary action of the upward
movement of water in drip systems also can move salt
into the root zone.
Greater agronomic flexibility.
Growers who use mechanized can do more things on more crops than they can with surface or drip irrigation. The high clearance allows mechanized to be used on most commonly
grown crops other than fruit trees, such as vegetables,
alfalfa and corn. Mechanized is preferable on crops
where surface water application is necessary to germinate
seed and stabilize soils. Mechanized systems also
can be used to apply foliar crop protection products and
cool temperature-sensitive crops such as corn. Finally,
because row spacing is not predetermined, it is easier to
rotate to other crops when using mechanized.
Affordability for lower-value crops. Because mechanized is cost-efficient, it also can be used on lower-value crops, such as field corn grown for dairy feed.
NOTES
*Managing the Lifeblood of California Agriculture.
grown crops other than fruit trees, such as vegetables,
alfalfa and corn. Mechanized is preferable on crops
where surface water application is necessary to germinate
seed and stabilize soils. Mechanized systems also
can be used to apply foliar crop protection products and
cool temperature-sensitive crops such as corn. Finally,
because row spacing is not predetermined, it is easier to
rotate to other crops when using mechanized.
Affordability for lower-value crops. Because mechanized is cost-efficient, it also can be used on lower-value crops, such as field corn grown for dairy feed.
NOTES
*Managing the Lifeblood of California Agriculture.