Document Type

Thesis - Open Access

Award Date

2015

Degree Name

Master of Science (MS)

Department

Plant Science

First Advisor

Douglas D. Malo

Abstract

Recent (1990-2014) increases in salt affected soils in the Northern Great Plains states of South Dakota (SD) and North Dakota (ND), MLRA 55B and 55C, have prompted more intensive research on groundwater derived saline and sodic soil characteristics in semi-humid and humid climates. Past research has focused on salinity and sodicity in irrigated agricultural systems in semi-arid and arid climates. Due to the disconnect between prior research and current problems in this region, it is necessary to assess widely used laboratory methods, and determine if short cuts can be used for rapid evaluation. The objectives of this research were: 1) to establish a relationship between soil electrical conductivity (EC) and the total soluble cations (TSC); 2) establish the relationships between EC of saturated paste extraction solutions, 1:1, and 1:5 soil:water extraction dilutions; and 3) to assess the field scale spatial distribution of saline and sodic soil properties in order to identify soils at high risk of developing saline and sodic issues in the future. EC, soluble sodium (Na+), calcium (Ca2+), and magnesium (Mg2+) and the sodium adsorption ratio (SAR) were measured for soil samples collected from four sites across SD and N research established a robust linear relationship between EC and TSC of TSC = 13.54 *EC – 0.29 (R2 = 0.88). Based on the results of the second study, not only can linear regression relationships be developed between saturated paste extractions and various soil:water dilutions, but a non-linear relationship can also be established to predict the salinity parameters based on the dilution factor. Finally, the third study found that while the prediction maps generated using ordinary kriging were not statistically significant, they showed that the salt affected soil area increased with depth. Soils that lack saline and sodic soil problems at the surface, but have moderate saline and sodic soil problems in the subsurface should be considered high risk for developing more severe limitations in the future when capillary and groundwater rise could bring soil solutes to the soil surface.

Library of Congress Subject Headings

Soils -- South Dakota --Testing
Soils -- North Dakota -- Testing
Soils, Salt in
Sodic soils

Description

Includes bibliographical references

Format

application/pdf

Number of Pages

136

Publisher

South Dakota State University

Rights

Copyright © 2015 Rachel K. Owen

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