Water Conservation Tips for... Farmers, Growers and Agriculture
The Intelligent Use of Water™ is about using water efficiently – in the most precise and even manner possible, minimizing waste. The following is information regarding practices and products that can be used to manage water more efficiently in agricultural applications.
1. Use the right amount of water at the right times
Growers can avoid runoff and maximize water use efficiency by applying the right amount of water at the right time. This is commonly called irrigation scheduling and involves 1) knowing how much water the crop needs, and 2) knowing how much the irrigation system applies. Once these two pieces of information are known, the grower can schedule when to irrigate, and for how long.
To answer the first question, “how much water does the crop need," growers first calculate the crop’s “consumptive use” of water on a daily basis. This is normally expressed as the crop’s evapotranspiration rate (ET rate) in inches of water per day. The ET for any given crop may be obtained from federal, state and/or county agencies serving the agricultural communities, and is derived from weather, historical and research data. It will vary by crop, by stage of plant growth, by region and by time of the year. For instance, a mature orchard in California could use .30” of water per day during a summer month.
To answer the second question, “how much water does the irrigation system apply,” the grower needs to calculate the system’s precipitation rate in inches of water per hour. Since there are 27,154 gallons of water per acre inch, it is easy to calculate precipitation rate if you know the irrigation system flow rate and the irrigated area. Simply divide the total number of gallons applied per acre per hour by 27,154 to calculate the precipitation rate. For instance, an orchard sprinkler system could apply .30” of water per hour.
Once the consumptive use and precipitation rate are known, the grower can estimate how many hours, or minutes, of operation are needed per day. In the simplified example above, the grower would need to irrigate one hour each day to satisfy consumptive use of the crop. If the grower wishes, consumptive use for several days may be combined, and a longer run time may be employed.
Many factors influence irrigation scheduling. Growers may wish to adjust the frequency and duration of their watering due to soil type, wetted area, actual and desired rooting development, water availability, desired deficit and/or leaching requirement. Of course, irrigation schedules are often adjusted to accommodate cultural practices, too.
Various types of irrigation systems are available and should be chosen carefully depending on the crop and the application. Below are guidelines to help growers choose the right system:
Flood irrigation is used when water is plentiful, runoff can be returned to the delivery system and is of high enough quality to be reused, and when targeted irrigation is unimportant. Flood is typically used when slopes are mild enough to prevent erosion, but steep enough to ensure water reaches the bottom end of the field without oversaturating the top end of the field. Although flood systems are usually less efficient than sprinkler, micro or drip systems, they may be operated with acceptable efficiency. However, evaporation losses may be extreme in arid climates, and growers lack flexibility in water application duration and frequency.
Sprinkler irrigation is used in a variety of agricultural applications for germination, irrigation, dust control, climate control and wastewater dispersal. The types of sprinkler systems commonly used include:
Solid Set – Solid set sprinkler systems, whether permanent or hand move, are a popular way to irrigate a wide variety of crops including field, row and permanent crops. Solid set sprinkler systems may be used on flat to severe topography in virtually any climate. Although hand move solid set systems may be labor intensive, they provide the grower a wide range of flexibility.
Mechanized Pivot/Linear Systems – Mechanized systems are commonly used in large open fields with flat to moderate topography. They may be fitted with overhead sprinklers or sprinklers mounted onto drop pipes or tubes. Labor savings may be realized due to the automated nature of these systems, but the corners of circular pivots create irrigation challenges, as do the water delivery systems for linear systems. They are typically used for agronomic field crops, and sometimes used for horticultural vegetable and fruit crops.
Wheeline - Wheeline systems are fitted with medium sized sprinklers and are typically used in smaller rectangular fields with flat to moderate topography on lower value field crops. It is a good choice where efficiencies higher than flood are desired and when other types of sprinkler systems are too labor or capital intensive.
Travelers – Travelers are typically fitted with large gun type sprinklers and are used to supply supplemental irrigation on crops which are not adversely affected by the guns’ large droplet sizes. Similar to wheelines, they are used when efficiencies higher than flood are desired and when other types of sprinkler systems are too labor or capital intensive.
Micro-irrigation – Micro-irrigation normally refers to the use of micro-spray and/or micro-jet irrigation equipment. These products are typically used in orchard, vineyard and nursery/greenhouse applications. Micro-irrigation is more targeted than traditional sprinkler or flood irrigation, but requires management of water quality to avoid plugging of the emission devices. Growers often take advantage of the variety of wetting patterns offered by micro-irrigation to accommodate and manipulate growing root zones of young trees and vines, and to control the climate of the orchard or greenhouse.
Drip irrigation – Drip irrigation normally refers to the use of polyethylene tubes fitted with emission device outlets at various spacing. There are a wide variety of tube and emission device sizes and quality, ranging from inexpensive tubes appropriate for annual usage to high quality tubes appropriate for the life of a permanent crop. Emission devices may be pre-inserted during the manufacturing process, or installed afterwards directly onto the laterals or via smaller tubes that transition from the lateral tubes to the emission device. Growers take advantage of drip to target irrigation to the root zone of the plant, and to improve the overall uniformity of water application. Drip is typically used in row crop, orchard, vineyard, nursery and greenhouse applications. The chief advantages include water savings and the ability to spoon feed and manipulate the crop, but water quality must be managed to avoid plugging of the emission devices.
3. Automate the irrigation system to improve profits and save water.
Irrigation systems use valves to turn irrigation “sets” on and off. These valves may be operated manually, or may be easily automated using controllers and solenoids. Automating farm or nursery irrigation valves allows growers to apply the right amount of water at the right time, regardless of the availability of labor to turn valves on and off. In addition, growers using automation equipment are able to reduce runoff from overwatering saturated soils or pots, reduce wind drift from irrigating at the wrong time of day, use labor for higher value tasks, and improve crop performance by ensuring adequate water and nutrient availability when needed.
Automation can be simple or sophisticated. A simple way to achieve automation is to buy a hand held controller and fit each valve with a solenoid/receptor assembly. A more sophisticated way to automate is to buy a central control system that employs the use of a computer and wired or wireless valve control. Both have their advantages and disadvantages including expense, level of expertise required, and overall automation capabilities. In both cases, the benefits are the similar: automation improves profits and saves water.
4. Apply effluent wisely to save water and avoid ground water pollution.
Land application of wastewater is beneficial in sensitive environmental areas where soils are shallow or where the advanced nutrient removal capabilities of vegetation are desired. Land application is an option where point source discharges are unavailable, such as areas with endangered streams. By only applying nutrient levels that the vegetation is able to use, deep leaching and ground water contamination can be avoided.
Dispersal options include spray irrigation over the top of vegetation, or drip irrigation directly to the soil surface. Where spray irrigation is used in sensitive areas, uniformity and precise rates of application are critical. Sprinklers with high uniformity, dependability, and tolerance to grit are desired.
Drip dispersal systems are rapidly achieving acceptance as one of the more advanced methods of wastewater treatment. They often offer flexibility for site location in sensitive or limited areas. They may also help address any runoff concerns. It is critical, however, to use dripline with a high uniformity emitter and with exceptional tolerance to suspended solids.
For more information, visit our Technical Resource page for information on Rain Bird sprinkler and drip products appropriate for usage with wastewater effluent. If you have other questions or want more information, please use our online referral page to locate your nearest Authorized Rain Bird Agricultural Irrigation Dealer.
5. Take advantage of the Irrigation Association’s Certification Program.
The mission of the Irrigation Association (IA), a non-profit, North American organization, is to improve the products and practices used to manage water resources and to help shape the worldwide business environment of the irrigation industry. The IA’s interest in water resources encompasses the application, conservation, drainage, improvement and recovery of water for economic and environmental enhancement in agriculture, turfgrass, landscape and forestry.
One of the IA’s chief roles is the establishment of recognized standards and guidelines dealing with irrigation related products, engineering applications and practices worldwide. To this end, the IA provides Certification Programs for Irrigation Specialists to become more knowledgeable about designing and installing efficient irrigation systems. Much of the coursework includes information on water-conserving products and techniques that benefit growers worldwide.
Recently, the US Department of Agriculture’s Natural Resources Conservation Services (NRCS) and the IA signed a Memorandum of Understanding that recognized the IA’s Certified Irrigation Designers (CID’s) as being qualified to becoming Technical Service Providers (TSP’s) for the Environmental Quality Incentives Program (EQIP) and companion conservation programs. This marks a unique cooperative relationship between the IA and the government, and underscores the importance of the IA’s certification programs. Growers would be wise to consult with IA certified designers when buying, retrofitting or managing an irrigation system.
For more information, contact the Irrigation Association. If you have other questions or want more information, please use our online referral page to locate your nearest Authorized Rain Bird Agricultural Irrigation Dealer.
