Thesis
Controls on spatio-temporal variability of exchangeable bases and base saturation in a dryland agricultural field
Washington State University
Master of Science (MS), Washington State University
2017
Handle:
https://hdl.handle.net/2376/101031
Abstract
Soil acidification threatens base cation status in agricultural soils in the semiarid Palouse River Basin of eastern Washington and northern Idaho, where over 65% of the region's surface 30 cm are acidified to below pH 6. Understanding the processes and drivers of acidification and resultant spatio-temporal variability of soil pH, base cations, and base saturation is key to comprehending how management practices may impact future sustainability of agricultural soils. The three objectives of this study were to (1) investigate spatio-temporal variability of soil exchangeable base cations and pH in soil profiles to a depth of 150 cm, (2) identify processes and drivers of base cation and pH variability, and (3) develop a model for the prediction of percent base saturation based on soil properties and terrain attributes. Soil pH, exchangeable base cations, and percent base saturation were measured at twenty-one sampled locations on the Cook Agronomy Farm (CAF) during the spring and fall periods of 1999, 2008, and 2015. Average soil pH and percent base saturation tended to increase with depth from the soil surface to the subsurface. However, average soil pH tended to decrease over time from soil surface to 30 cm depth and increase over time below 30 cm depth while average base saturation decreased slightly over time at all depths. Exchangeable base cations (meq/100g) tended to increase with depth from soil surface to subsurface except K+, which tended to decrease with depth. Exchangeable base cations tended to decrease between 2008 and 2015 at all depths with the exceptions of K+, which tended to increase from soil surface to 10 cm and 20 to 30 cm depth and Ca2+ and Mg2+ which tended to increase at depths below 120 cm. Drivers of base cation and base saturation variability included hydrologic processes and terrain attributes. Predictive models showed differences in the variables useful in explaining each exchangeable base cation's variability. Five variables, sampling depth, pH, relative yield, specific catchment area, and fall electrical conductivity, were found to be useful in explaining the variability of percent base saturation.
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Details
- Title
- Controls on spatio-temporal variability of exchangeable bases and base saturation in a dryland agricultural field
- Creators
- Kayla Beth Jones
- Contributors
- C. Kent Keller (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Environment, School of the (CAHNRS)
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525294301842
- Language
- English
- Resource Type
- Thesis