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Tools can help producers become more efficient irrigatorsBy Kylene Orebaugh The Internet can be a helpful tool when it comes to making decisions for crop irrigation. So can agricultural professionals trained to help farmers make important choices. From an Extension service fact sheet, to an energy estimator from the Natural Resources Conservation Service, to association news with the latest technologies, each can be helpful in deciding what crop to grow to how much water to apply to the chosen crop. NRCS irrigation awareness tool Located at http://ipat.sc.egov.usda.gov, the irrigation energy estimator helps a producer estimate the energy cost of pumping water in their irrigation operations. According to the website, NRCS technical specialists have developed the cost estimates based on irrigation methods for predominant crops in a certain state. However, this tool does not provide field-specific recommendations, but rather evaluates the options based on user input. The third in a series of web-based tools from NRCS, the estimator helps identify water usage and fuel costs based on the crops being grown and considering certain settings on the farm. They also have tools for animal housing, nitrogen and tillage. On the first page of the irrigation energy estimator, a producer is required to put in his location using a ZIP code for the first step of the analysis. In step two, there is a page where users choose their hydraulic setting and irrigation system. Here, users must input the following settings: --Well lift; --System pressure; --Energy cost; --Use of a flow meter; --Use of irrigation scheduling; --Whether or not regular maintenance and upgrades occur. Step three allows users to select a common crop and input the number of acres to be irrigated. A default value (ac-in/acre) will appear for each crop for the average gross seasonal water application depth. However, if a user knows his specific gross seasonal application depth, he can enter the value and all computations will be based on the value entered. The process culminates in step four where all the inputs are analyzed. Factors considered here are: --Adding a flow meter; --Implementing irrigation scheduling; --Conducting system maintenance and upgrades. From the inputs in step four, a report is generated. It indicates irrigation system water use and cost estimates for the selected crop, and compares it with projected use and costs for the system after irrigation system modifications have been implemented to improve efficiency. The report also shows estimates of energy cost and potential cost savings if producers were to implement recommendations of a pumping plant evaluation with the corresponding irrigation system modifications. For additional information, visit a local NRCS office. Extension resources University Extension services are valuable tools for information seekers. Many have fact sheets and publications available online or in local Extension offices. The national Extension website, www.extension.org, is a compilation of resources from academia. Tying into the issues related to the NRCS irrigation awareness tool, irrigation scheduling is an important part of the watering process. A fact sheet can be found at www.ext.colostate.edu/pubs/crops/04708.html. "The purpose of irrigation scheduling is to determine the exact amount of water to apply to the field and the exact timing for application," the sheet by I. Broner states. "The amount of water applied is determined by using a criterion to determine irrigation need and a strategy to prescribe how much water to apply in any situation." According to the paper, there are several advantages to scheduling irrigation. --The farmer is able to schedule water rotation among fields to minimize crop water stress and maximize yields. --It can help reduce the cost of water and labor through fewer irrigations, making maximum use of soil moisture storage. --Fertilizer costs are lowered by holding surface runoff and deep percolation or leaching to a minimum. --Net returns can be increased by increasing crop yields and quality. --Water logging is minimized by reducing drainage requirements. --Root zone salinity problems are better controlled through controlled leaching. --Additional returns can result by using the "saved" water to irrigate non-cash crops that would otherwise not be irrigated when there is a shortage. According to the paper, research in Nebraska (where most water is pumped), shows irrigation scheduling provides an average 35 percent savings in water and energy. "In fuel costs alone, this is a per-season savings of about 550 kwh per acre for a center pivot sprinkler or about 200 kwh per acre for gated pipe." There are several methods for irrigation scheduling. Several examples are: --Hand feel and appearance of soil. Moisture is measured by feel using a hand probe. It is easy to do and can improve accuracy with experience. However, it involves field work and accounts for low accuracies. --Gravimetric soil sample. This method finds moisture levels by taking samples using augers, a cap or oven. It has high accuracies, but is labor intensive and takes time. --Tensiometers. Measures soil moisture tension using tensiometers which include a vacuum gauge. It does have good accuracy and is instantaneous, but requires some labor, needs maintenance and has breaks at certain tensions. --Electrical resistance blocks. Uses the electrical resistance of soil moisture using a resistance block AC bridge (meter). It is instant and works over a large range of tensions, as well as having the ability to be used remotely, but it is affected by soil salinity, not sensitive enough at low tensions and needs maintenance and field reading. --Water budget approach. A weather station or available weather information is used to evaluate various weather changes to predict how fast the water will evaporate. This method is fairly flexible and can help forecast irrigation needs in the future with the same equipment for a number of fields. It does need to be calibrated and adjusted; calculations can be difficult without a computer. --Modified atmometer. An atmometer helps give an estimate of the soil moisture. It is easy to use for a direct reading of the reference evaporation rate, but is only an estimation and needs calibration. For more information about irrigation scheduling visit, www.ext.colostate.edu, or visit with your local county cooperative Extension agent. Other helpful irrigation tips and facts can be found at http://www.ag.ndsu.nodak.edu/abeng/irrigation.htm#irrigationwatermanagement. Other resources Both the USDA and NRCS, as well as Extension personnel, are good places to start when making irrigation planning choices. Other places to go may be ag instructors at the local community college or high school, crop consultants or irrigation specialists. Kylene Orebaugh can be reached by phone at 620-227-1804 or by e-mail at kscott@hpj.com. 4/7/08 Date: 4/3/08 Advertisement
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