Water saving technologies in U.S. irrigation

Authors: Evett, Steven - Steve; Vories, Earl; Stone, Kenneth; Sui, Ruixiu; Trout, Thomas; Reba, Michele; Bronson, Kevin

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/12/2014
Publication Date: 9/12/2014
Citation: Evett, S.R., Vories, E.D., Stone, K.C., Sui, R., Trout, T.J., Reba, M.L., Bronson, K.F. 2014. Water saving technologies in U.S. irrigation [abstract]. Sino-US workshop on water use efficiency in Yangling, China, Sept. 12. skp

Interpretive Summary:

Technical Abstract: In the United States, less than 2% of citizens work on farms, yet agriculture production accounts for 16% of the $9 trillion gross domestic product, 8% of exports and 17% of employment. Since WWII, the growth of agricultural inputs has remained flat, while productivity has increased 250%, largely due to the large increase in irrigated acreage during that period, but also due to the great improvements in crop genetics, fertilization, irrigation methods and irrigation management engendered by scientific effort addressing agricultural problems. During the same period, water use per acre in agriculture has dropped by 50% due to the advent of pressurized irrigation systems and advanced application methods and management. Today, irrigated agriculture produces 40% of global food supply on only 18% of total cropped area, but irrigation uses just 34% of water in the nation. Nonetheless, there are great challenges to sustainable water use in agriculture due to trends in resource use and population, which result in increasing demand by cities and industries and less water available to agriculture in many parts of the USA. The USDA Agricultural Research Service (ARS) is charged with extending the nation's scientific knowledge and solving agricultural problems through its four national program areas: 1) Nutrition, food safety and quality; 2) Animal production and protection; 3) Natural resources and sustainable agricultural systems; and 4) Crop production and protection. Irrigation water management is addressed by ARS largely through National Program 211, Water Availability and Watershed Management, specifically in Problem Area 1, Water Management, which has five objectives: 1) Managing and scheduling irrigation for efficient water use; 2) Innovative surface and subsurface irrigation tools and techniques; 3) Improved irrigation and cropping for reuse of degraded water; 3) Sensor technologies for site-specific irrigation water management; and 4) Cropping and management strategies under limited water supplies. ARS currently implements 201 research projects related to irrigation, 163 of which include irrigation in the research approach and 177 of which include irrigation in the research objectives, while 53 are primarily devoted to solving irrigation problems. As water resources become more limited and the cost of pumping increases, it is becoming economically critical to irrigate only as much as needed for optimal economic return. Such precision irrigation avoids over irrigation and the lost of nutrients to deep percolation, thus saving both in pumping costs and in fertilizer costs. The result is often increased yields as nutrients are held in the root zone, furthering yield development. Several ARS laboratories are measuring water use and yield of specific crops in response to new irrigation methods and management. New sensors are being developed to measure soil water status and plant water stress so that irrigation can be delivered when and as needed. All these laboratories are determining the amount of yield gained per unit of water used for each method of application and management, the so called crop water productivity, which is a key indicator of productive water use. Another aspect of precision irrigation is accurate water application in time and space. Pressurized irrigation systems are amenable to computer control and can often be configured to apply water in one place and not another. The sensors developed by ARS scientists are engendering a new era of computer control of precision irrigation systems that allows controlled deficit irrigation, further increasing the crop water productivity while lowering pumping costs and allowing an economically optimal result. The resulting irrigation automation systems developed by ARS scientists can reduce management effort while improving production and using fewer energy, water and nutrient reso