Degree Type

Dissertation

Date of Award

1981

Degree Name

Doctor of Philosophy

Department

Agronomy

Abstract

The objective of Part I of this study was to investigate water table relationships among soils in both an artificially tile drained and undrained traverse and develop mathematical water table prediction equations for each soil within each traverse and each entire traverse. Soil development among several members of a toposequence consisting of a Typic Hapludoll, Aquic Hapludoll, Typic Haplaquoll, Calcic Haplaquoll, Typic Calciaquoll, and Cumulic Haplaquoll in a closed drainage system was either directly or indirectly influenced by water table fluctuations. Time of the year in conjunction with meterological variables of antecedent and cumulative precipitation, evapotranspiration, and net water were used to develop regression models. Water table inflections decreased as percent slope decreased and distance from watershed edge increased. Depth to water table was generally 0.7 m deeper in the artificially tile drained traverse. Regression models were used to estimate depth and duration of water tables for any position along either drained or undrained traverses;The objective of Part II of this study was to determine if there were differences in clay and total phosphorus distributions among and between soils of artificially tile drained and undrained traverses. The tile drain had been installed approximately 80 years ago. Water tables had little or no effect on clay or total phosphorus distribution in either tile drained or undrained Clarion, Typic Hapludoll, sola. Higher percentages of clay in the sola and more total phosphorus translocation (100 to 180 cm depth) were found in Aquic Hapludoll through Cumulic Haplaquoll soils. Differences in average percent clay and total phosphorus were due to variability of till, but incipient acceleration of clay and phosphorus was suggested for the tile drained traverse;The objective of Part III was to measure in situ electrode potentials (Eh) for the soils in Part I and to estimate the chemical weathering environments. Platinum electrodes in conjunction with a reference Calomel electrode were used successfully in estimating relative differences between weathering environments, associated water tables, and soil colors for all soils of the undrained traverse. Eh was related to oxidized environments of Typic Hapludoll in the tile drained traverse but Eh did not relate to oxidized-reduced environments, associated water tables, and soil colors for remaining soils in the tile drained traverse.

DOI

https://doi.org/10.31274/rtd-180813-5484

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Harry Rudolph James

Language

en

Proquest ID

AAI8209132

File Format

application/pdf

File Size

398 pages

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