Susan O’Shaughnessy,Manuel Andrade,Steven Evett,Paul Colaizzi 2016-06-29 04:33:16
Efficient use of water resources is critical to the Texas High Plains, a region in the Panhandle of Texas that represents only 10% of the state’s land area but almost 28% of the state’s irrigated acreage. The Ogallala Aquifer supplies most of the water for agriculture in this region. Minor aquifers include the Blaine, Dockum, and Whitehorse, which mainly support the surrounding municipalities and industries. Despite plentiful rainfall in 2015, the average water level in the Ogallala Aquifer continues to decline. Water conservation districts across the state and the Texas Development Water Board are actively promoting strategies for efficient management of water resources to sustain the rural economies and the environment. The trend toward efficiency As part of this effort, irrigation methods across Texas continue the trend toward greater efficiency. The percent of irrigated acreage supplied by gravity- fed systems fell from 19% in 2008 to 12% in 2012, while the irrigated acreage with sprinkler and drip systems increased by 4% and 3%, respectively. Center pivots are the mainstream (94%) of sprinkler irrigation systems in Texas. A reduction in water losses that do not contribute directly to crop production has also been demonstrated. The majority of farmers in the Texas High Plains now use in-canopy drops or low-elevation spray application (LESA), and some have adopted low-energy precision application (LEPA) bubblers or LEPA drag socks. These application methods reduce losses due to evaporation and wind as compared with drops at mid-elevation heights or impact sprinklers mounted on a moving lateral. When using in-canopy drops, planting crops in a circle under a center pivot provides more uniform distribution of the irrigation water. Further reductions in evaporative losses can be achieved using subsurface drip irrigation—as much as 4 to 5 inches less evaporative loss compared to mid-elevation spray irrigation in the windy Panhandle environment. However, the Texas Water Resources Institute predicts that by 2060, municipal demand for water will increase to 47% of the state’s total water demand due to population growth. This prediction continues to pressure irrigated agriculture to reduce water use by conserving water, growing drought-tolerant crops, improving irrigation scheduling, and adopting advanced irrigation management technologies. There have been steady advances in the research and development of irrigation management technologies in different parts of the U.S. At the USDA-ARS Conservation and Production Research Laboratory in Bushland, Texas, we are developing a supervisory control and data acquisition (SCADA) system to help farmers manage water more efficiently. What is SCADA? In brief, a SCADA system uses various sensors strategically located within the environment to provide optimal control of system processes and early warning of potential failures. Our irrigation scheduling SCADA system (or ISSCADA) supports site-specific irrigation management by integrating: (1) measurements from plant canopy temperature, soil water, and weather sensors with (2) plant stress-based irrigation scheduling methods, and (3) a commercial variable-rate irrigation (VRI) center pivot system. Wireless infrared thermometers are mounted on the ISSCADA-equipped center pivot system, providing continuous canopy temperature measurements as the system moves across the field. An embedded computer at the center pivot point collects all data streams. A few wireless infrared thermometers are stationary in the field over a well-watered crop to provide a reference temperature curve. This is used to scale the onetime- of-day remote temperature measurements as the ISSCADA system travels across the field. Soil water sensors provide feedback and redundancy as to how well crop stress is detected by the canopy temperature sensors, and they can be used to provide feedback over areas where the ISSCADA system does not travel during daylight hours. The ISSCADA system can be controlled remotely by means of a client-server program developed by the ARS. This program incorporates a user-friendly graphical user interface (GUI) to aid in configuring and operating the ISSCADA system, and it uses geographic information system (GIS) concepts to facilitate the spatial and temporal analysis of the information collected by the sensors. The overall goal of the ISSCADA system is to detect crop stress across different areas of a field throughout the irrigation season and provide irrigation recommendations to the farmer. Canopy temperature measurements or calculated crop water stress indices (CWSI) are plotted geographically to create maps that are displayed using the GUI. The maps show the locations and levels of canopy temperature and crop stress for the part of the field that the ISSCADA system traveled over during daylight hours. These maps are a visual guide to the farmer and indicate areas within the field that require attention. The ISSCADA system also provides prescription maps to aid the farmer in irrigation scheduling by showing which management zones within the field require water and the amount of water required. Irrigation timing is accomplished by establishing thermal stress index thresholds for each management zone. When the threshold is exceeded, an irrigation is triggered. The farmer can remotely access the prescription map, review it, and accept or modify the irrigation recommendations. Uploading the prescription to the center pivot’s control panel through the GUI causes the irrigation system to apply the prescribed irrigation depths. The client-server software provides an integrated environment for communication between the ISSCADA system and the irrigation equipment. Similar to other SCADA systems, the ISSCADA system also allows operation of multiple irrigation systems. In addition, the prescription maps are dynamic, responding to spatially variable crop water needs throughout the irrigation season. After an irrigation season, the farmer can use the GUI to enter historical information for each management zone (e.g., intra-seasonal information, such as average CWSI and soil water content for the zone, and inter-seasonal information, such as yields and total seasonal irrigation amounts). The information is stored in relational databases that can provide an additional layer of information for the next growing season. The ISSCADA system and its client-server software are ultimately decision support tools. The farmer can view various layers of information pertaining to the field and has the choice to accept the recommendations of the prescription map, or modify the map, before uploading it to the center pivot’s control panel using the GUI. More to come As with any new technology, beta testing in different climates and with different crops is needed to determine crop responses to irrigation management using the ISSCADA system. As partners in a cooperative research and development agreement (CRADA), Valmont Industries and ARS scientists at three sub-humid and humid locations, in addition to Bushland, will pursue beta testing of the ISSCADA system to help facilitate its commercialization. We also acknowledge two other CRADA partners with whom we have worked to develop the sensors used in the ISSCADA system: Dynamax, Inc., with whom we have a CRADA for commercialization of the wireless infrared thermometer network, and Acclima, Inc., who is our CRADA partner in the development of the TDR soil water sensors. Further Reading Andrade, M. A., O’Shaughnessy, S. A., & Evett, S. R. (2015). Advances in irrigation management tools: The development of ARSmartPivot. ASABE Paper No. 152170793. St. Joseph, Mich.: ASABE. http://dx.doi.org/10.13031/irrig.20152170793 Evett, S. R., Brauer, D. K., Colaizzi, P. D., & O’Shaughnessy, S. A. (2015). Corn and sorghum performance as affected by irrigation application method: SDI versus mid-elevation spray irrigation. In Proceedings of the 27th Annual Central Plains Irrigation Conference (pp. 83-95). Colby, Kans.: Central Plains Irrigation Association. https://www.ksre.k-state.edu/irrigate/oow/p15/Evett_15R.pdf O’Shaughnessy, S. A., Evett, S. R., Colaizzi, P. D., & Howell, T. A. (2013). Wireless sensor network effectively controls center pivot irrigation of sorghum. Applied Engineering in Agriculture, 29(6), 853-864. http://dx.doi.org/10.13031/aea.29.9921 O’Shaughnessy, S. A., Evett, S. R., & Colaizzi, P. D. (2015). Dynamic prescription maps for site-specific variable-rate irrigation of cotton. Agricultural Water Management, 159, 123-138. http://dx.doi.org/10.1016/j.agwat.2015.06.001 The USDA is an equal opportunity provider and employer. The mention of trade names, commercial products, or companies in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the USDA. ASABE member Susan O’Shaughnessy, Research Agricultural Engineer, email@example.com; ASABE member Manuel Andrade, ORISE Post-Doctoral Fellow, firstname.lastname@example.org; ASABE member Steven Evett, Senior Research Soil Scientist, email@example.com; and ASABE member Paul Colaizzi, Research Agricultural Engineer, firstname.lastname@example.org, USDA-ARS Conservation and Production Research Laboratory, Bushland, Texas, USA.
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