Precision agriculture and irrigation: Current U.S. perspectives

Authors: Evett, Steven - Steve; O`Shaughnessy, Susan; ANDRADE, MANUEL - Orise Fellow; Kustas, William - Bill; Anderson, Martha; Schomberg, Harry; Thompson, Alondra

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/19/2019
Publication Date: 3/9/2020
Publication URL: https://handle.nal.usda.gov/10113/6934599
Citation: Evett, S.R., O'Shaughnessy, S.A., Andrade, M.A., Kustas, W.P., Anderson, M.C., Schomberg, H.H., Thompson, A.I. 2020. Precision agriculture and irrigation: Current U.S. perspectives. Transactions of the ASABE. 63(1):57-67. https://doi.org/10.13031/trans.13355.
DOI: https://doi.org/10.13031/trans.13355

Interpretive Summary: The decreasing supply of water from the Ogallala and High Plains aquifers for irrigation is a threat to agricultural productivity and sustainability in the Southern High Plains of Colorado, Kansas, Oklahoma and Texas. Agricultural production practices, including irrigation, must become more efficient in order to sustain productivity in the face of declining and increasingly expensive resources. Precision agriculture and irrigation methods are effective responses to this challenge. Based on GPS location and guidance systems and mapping, precision planting, fertilization and weed control optimize crop production and return on dollars spent on inputs. Precision irrigation systems based on weather, soil and plant sensing, enable irrigation response to crop water needs as needs vary in space and time during stress periods and critical crop growth periods, thus helping to maintain yields in the face of declining water availability. Scientists and Engineers at the USDA ARS Conservation and Production Research Laboratory, Bushland, Texas, developed sensor systems and variable rate irrigation (VRI) control systems that are user friendly and provide irrigation recommendations that can be used easily in combination with a variable rate center pivot irrigation system. The system uses either the speed control that is available on all center pivots or the speed and zone control that are available on VRI center pivots. A major center pivot manufacturer has licensed the system and plans to make it available to farmers. Cooperation with USDA ARS scientists at Beltsville, Maryland has resulted in new wireless soil water networks that provide data to farmers and irrigation managers through the Internet. Other USDA ARS scientists in Maryland have developed a system to use data from multiple satellites to provide maps of ET that producers can use for irrigation management and are growing the system to cover the entire USA. This combination of bottom up and top down irrigation management approaches gives producers great flexibility in choosing the system that works best for them.

Technical Abstract: Precision Agriculture (PA) as a conceptual framework for farming operations responds to the need to manage inter-field and intra-field variability on farms, within watersheds, regionally and internationally. How PA is used, the objectives involved, and the technologies that support it have changed substantially since the inception of modern PA in the 1980s when the U.S. Global Positioning System (GPS) became available for public use. Coupled with geographical information system (GIS) computer technologies that were first developed for satellite imagery, PA became a mainstream tool for farmers to plan site-specific agricultural operations, early on including fertilizer application, followed by seeding rate, seed variety, pesticide spraying and now site-specific irrigation. Equipment with GPS steering and position-aware supervisory control systems allowed pre-determined site-specific prescription maps to be downloaded into equipment and used, for example, to turn off a spraying system as it passed over a waterway. GPS-enabled harvesting equipment produced yield maps that were some of the first data to be used for site-specific management, often with confusing results due to a lack of co-varying field data and adequate decision support systems (DSS) based on how soil spatiotemporal properties influence plant development. This kind of passive and indirect PA has evolved, however, to provide more capable solutions for precision management. One example provides for variable rate application of fertilizers based on georeferenced soil sampling that leads to prescription maps of fertilizer need. Another example facilitates spatially variable irrigation management based on 30-m resolution maps of crop water use developed from multi-satellite data fusion. Many of the more successful PA technologies involve on-board sensor systems that feed data to embedded computing platforms that make on-the-fly adjustments to equipment. Such active and direct PA systems use modern technology that provides the ability, for instance, to turn spray equipment on in the presence of weeds and off otherwise, or to turn on variable rate irrigation nozzles where abiotic stress sensors indicate crop water stress. Such supervisory control and data acquisition (SCADA) systems rely on algorithms based on sophisticated understanding of biophysics and biological systems. Today the confluence of computing power, data acquisition and management infrastructure, new modeling paradigms, and spatial decision support systems ushers in new possibilities for PA. Providers of PA services now include government institutions from national to local levels, private providers (often using publicly available data from government ground, aerial and satellite sensing systems), university extension systems and farmer cooperatives. Sources of data range from public domain to private data held by farmers or third parties. Questions around data standards, data sharing, data ownership, and public and private rights add further complexity to modern PA but are actively being addressed by both public and private institutions.