MICROMORPHOLOGY OF A SALT AFFECTED SOIL NEAR FARGO, NORTH DAKOTA

Soils high in salts pose many agricultural problems. Salts hinder plant growth and alter soil properties, and can be difficult to diagnose and remediate. There are two distinctive types of salt affected soils: saline and sodic. Saline soils contain high amounts of all salts, while sodic soils contain a high concentration of sodium salts in particular.

Traditional soil testing involves disaggregating a natural soil to determine chemical properties of the bulk sample. Conversely, micromorphology involves the analysis of undisturbed soil samples using microscopic techniques to determine the mineral constituents and their relation to weathering products and pore space geometry. This case study evaluates micromorphological changes throughout a soil profile of a salt affected soil in both vertical and horizontal orientations. In particular, this study assesses the spatial relationships and types of salts in the profile to gain a better understanding of how the salts accumulate.

The soil sampled is located on nearshore sediments of Glacial Lake Agassiz in central Cass County, ND. The soil is part of the Exline series, which consists of poorly to moderately well drained soils. They are classified as smectitic, frigid Natrudolls according to USDA Soil Taxonomy because of their high clay and salt content. Unproductive soils like these make accurate soil mapping challenging because it can be extremely difficult to separate saline from sodic phases.