Spatiotemporal variability of saturated hydraulic conductivity evident across agricultural management strategies

Authors: O'Brien, Peter; Papanicolaou, Athanasios - Thanos

Submitted to: American Geophysical Union
Publication Type: Abstract Only
Publication Acceptance Date: 9/24/2022
Publication Date: 12/14/2022
Citation: O'Brien, P.L., Papanicolaou, A.N. 2022. Spatiotemporal variability of saturated hydraulic conductivity evident across agricultural management strategies [abstract]. American Geophysical Union.

Interpretive Summary:

Technical Abstract: Saturated hydraulic conductivity, Ksat , is a dynamic hydropedologic property that is responsive to management practices and can be used to make critical insights into soil structure, erosional processes, and solute transport. However, Ksat measurements are often isolated, spot measurements that overlook spatiotemporal variability and limit the effectiveness of Ksat as an important indicator of landscape resiliency. In this study, field experiments were conducted at three hillslopes in southeast Iowa with different agricultural management practices, namely Conservation Reserve Program (CRP), no-till, and conventional till, to identify the effects of land use on Ksat variability. On average, 40 measurements per field were concomitantly performed using an array of semi-automated double ring infiltrometers (DRIs) to ensure adequate spatial representation of Ksat per hillslope. Two distinct patterns were observed in the developed Ksat spatial distribution maps for the three hillslopes. The map for the CRP hillslope showed a “strip pattern” while the cultivated fields depicted a “mosaic pattern”. The strip pattern at the CRP was attributed to past flow-driven preferential erosion along the main drainage-way, which removed the finer soil fractions and exposed a loam substratum with a relatively higher sand content that yielded higher Ksat values in the drainage-way. Conversely, the mosaic patterns in the no-till and tilled fields were attributed to the mixing of soil from cultivation during the crop rotations. However, the magnitude of variability within these measurements at each field indicated that a less intensive sampling regime may grossly misrepresent Ksat. Thus, these patterns would not have been observed without time-intensive measurements provided by the array of DRIs. To meet future research needs of assessing spatiotemporal variability, the employment of new generation infiltrometer sensors is required that can be automated to reach a “true” steady state condition reliably and consistently during each monitoring period.