Document Type

Thesis - University Access Only

Award Date

2011

Degree Name

Master of Science (MS)

Department / School

Plant Science

Abstract

Soil properties are dynamic throughout landform positions and vary with land management. Cultivation changes soil chemical and physical properties and the effects are intensified over time. Two studies were undertaken measuring soil attributes across landforms. Study 1 is a comparison of soil quality characteristics between a cultivated site in the process of conversion to native vegetation and a remnant tall-grass prairie at upland and wetland locations. Study 1 assesses the effects of long-term land uses examining commonly measured indicators of soil quality within and across landforms. It was hypothesized EcoSun Prairie Farm would have lower soil quality as a result of anthropogenic management than Sioux Prairie. Study 1 presents a unique opportunity to examine soil from an uncultivated tallgrass prairie remnant. Using Sioux Prairie as a reference site allowed the effects of cultivation and wetland drainage to be examined between two divergent land uses over a long period of time (approximately 120 years). This information allows an assessment of the degree of degradation that has occurred due to land use associated with cultivation. The remnant prairie contained higher soil organic matter (SOM), particulate organic matter (POM), wet aggregate stability (WAS), and microbial hydrolytic activity indicating lower overall soil health at the cultivated site. Significantly higher levels of SOM were measured for the footslope position compared with the backslope and upper shoulder positions. In contrast, there were no differences in SOM among landscape positions at the remnant prairie. The cultivated site contained approximately 50% of the SOM, 20% of POM, 50% of the microbial hydrolytic biological activity, and 33% of the WAS than the prairie remnant. The cultivated site also contained higher pH values at every depth of the footslope position compared with the uncultivated site. The undisturbed wetlands contained greater SOM, POM, and microbial activity than did the previously drained wetlands presumably due to microbial oxidation of organic matter after drainage. The recently rehabilitated wetlands contained only 50% SOM, 20% POM, 50% biological activity, and 80% of the WAS measured at the undrained wetland sites. Study 2 is an inventory of soil quality indicators at landforms across EcoSun Prairie Farm using zones based on digital elevation data and using the Tillage Erosion Prediction model to highlight areas most vulnerable to cultivation. This study presents a base data set available for future studies evaluating the degree that rehabilitation of native vegetation has on a section-wide (640 ac or 260 ha) land area. This study was conducted across multiple land uses as a snapshot in time and provides detailed spatial soil information for mapping over the study area. Study 2 examined the relationship of soil chemical and physical properties across five landscape positions with depth. Landscape positions were classified by creating a detailed digital elevation map to run the Tillage Erosion Prediction Model (TEP) and then sampled to represent all soil types, landscape positions, and current land uses present at the site. Landscape zones were compared within two soil associations: Wentworth-Egan (WeB) and Egan-Ethan (EeB). Association WeB showed no significant differences between zones whereas EeB showed differences in SOM, POM, FDA, pH, and EC between zones 2 compared with 4 and/or 5. The significance found in soil association EeB and the lack of significance in WeB is the result of differing soil properties related to the soils composing each association. Deeper soil profiles and less dramatic changes in topography of soils contained within soil association WeB account for the lack of significant differences between zones. Distinguishable differences in the depths of the soil profile contained within association EeB as well as more dramatic topography changes provided greater differentiation of soil properties between zones.

Library of Congress Subject Headings

Soils -- Quality

Land use, Rural -- Environmental aspects

Format

application/pdf

Number of Pages

132

Publisher

South Dakota State University

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