Comparative analysis of water budgets across the U.S. long-term agroecosystem research network

Authors: Baffaut, Claire; Baker, John; Biederman, Joel; Bosch, David; BROOKS, ERIN - University Of Idaho; Buda, Anthony; DEMARIA, ELEONORA - University Of Arizona; Elias, Emile; Flerchinger, Gerald; Goodrich, David - Dave; HAMILTON, STEVE - Michigan State University; Hardegree, Stuart; Harmel, Daren; Hoover, David; King, Kevin; Kleinman, Peter; Liebig, Mark; McCarty, Gregory; Moglen, Glenn; Moorman, Thomas; Moriasi, Daniel; OKALEBO, JANE - University Of Nebraska; Pierson Jr, Frederick; RUSSELL, ERIC - Washington State University; Saliendra, Nicanor; SAHA, AMARTYA - Archbold Biological Station; Smith, Douglas; Witthaus, Lindsey

Submitted to: Journal of Hydrology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/26/2020
Publication Date: 5/4/2020
Citation: Baffaut, C., Baker, J.M., Biederman, J.A., Bosch, D.D., Brooks, E.S., Buda, A.R., Demaria, E.M., Elias, E.H., Flerchinger, G.N., Goodrich, D.C., Hamilton, S.K., Hardegree, S.P., Harmel, R.D., Hoover, D.L., King, K.W., Kleinman, P.J., Liebig, M.A., McCarty, G.W., Moglen, G.E., Moorman, T.B., Moriasi, D.N., Okalebo, J., Pierson Jr, F.B., Russell, E.S., Saliendra, N.Z., Saha, A.K., Smith, D.R., Yasarer, L.M. 2020. Comparative analysis of water budgets across the U.S. long-term agroecosystem research network. Journal of Hydrology. 588. https://doi.org/10.1016/j.jhydrol.2020.125021.
DOI: https://doi.org/10.1016/j.jhydrol.2020.125021

Interpretive Summary: Intensified agricultural production coupled with increased frequency of weather extremes will affect soil water storage and water movement in agricultural landscapes. Understanding how management and climate may affect those is critical to using water more efficiently and sustainably. However, this understanding is largely incomplete. The Long-Term Agroecosystem Research (LTAR) network provides a geographically diverse and unique set of agricultural study sites in the US. The objectives of this study were to: 1) characterize the variability of water availability and movement across the LTAR network; 2) identify data gaps in our knowledge of water movement across the LTAR network; and 3) identify opportunities to leverage the LTAR network to improve understanding of water movement and storage across agricultural landscapes. For each of the 18 LTAR sites, we developed water budgets, which account for all of the inputs and outputs of water on an average annual basis. Datasets length ranged from three to 50 years, depending on the site. The network covers a range of precipitation from 240 to 1400 mm yr-1, evaporation and plant water uptake from 228 to 1080 mm yr-1, and surface runoff and subsurface flow from negligible to 1500 mm yr-1. However, uncertainties of where all the water is going remained high, in part because soil water storage and downward movement of water were often neglected or measured for very short periods. More accurate measurement of the major inputs and outputs, and direct measurement of water content and percolation are keys to understanding how agricultural lands affect water movement. These results will benefit water resource managers and scientists and inform policy makers.

Technical Abstract: Understanding the movement and storage of water within agricultural landscapes as functions of management and climate is essential for more efficient and sustainable water use. However, knowledge of water storage and fluxes on U.S. agricultural lands is largely incomplete. The Long-Term Agroecosystem Research (LTAR) network provides a unique and geographically diverse set of agricultural study sites in the United States. The objectives of this study were to: 1) characterize the hydrologic variability across the LTAR network; 2) identify data gaps in the water budgets across the LTAR network; and 3) identify opportunities to leverage the LTAR network to improve understanding of water budgets across agricultural landscapes. For each of the 18 LTAR sites, we developed water budgets on an average annual basis. Uncertainties for each component were based on the quantification method and the length of the data sets. Uncertainty propagation methods combined these uncertainties and the unquantified components to calculate an overall water budget uncertainty. Datasets length ranged from three to 50 years, depending on the component and the site. The network covers a range of precipitation from 240 to 1400 mm yr-1, evapotranspiration from 228 to 1080 mm yr-1, and surface runoff and subsurface flow from negligible to 1500 mm yr-1. However, uncertainties of where all the water is going remained high, in part because soil water storage and downward movement of water were often neglected or measured for very short periods, resulting in average water budget uncertainty of 25% of the water inputs. More accurate measurement of the major inputs and outputs, and direct measurement of water content and percolation are keys to understanding how agricultural lands affect terrestrial water budgets.