Master's Theses

Document Type

Thesis

Date of Award

Spring 2021

Degree Name

Master of Science (MS)

Department

Biology

Advisor

Dr. Mitchell Greer

Abstract

Throughout southwestern Kansas thousands of acres of native grassland have been converted to cropland for agricultural use, reducing native prairie by over 60% in the sandsage prairie. Due to low precipitation and arid conditions, much of these croplands are irrigated by center pivot irrigation systems fed by the Ogallala Aquifer. These fields are abandoned when the aquifers dry up, resulting in erosion of the unused farmland. Conservation programs such as the Conservation Reserve Enhancement Program (CREP) were established to address this problem but have been unsuccessful in restoring native grasslands in abandoned croplands in southwestern Kansas. We hypothesized that insect larvae infestation could be instrumental in the lack of vegetation establishment success. To address this, we investigated whether insecticide use would result in higher seedling survival and plant cover of native grasses. Using a custom seed mixture, we planted three strip plots in an abandoned center pivot located in Kearny County, Kansas and measured seed establishment and canopy cover in two transects per strip plot. The strip plots were divided into halves, with one half sprayed with insecticide and the other half used as a control. We found marginally significant difference in average median seed counts between unsprayed and sprayed plots, with sprayed plots having greater seedling counts. We also found significant difference in Total Plant cover and Planted Grass cover, with more Total Plant cover and Planted Grass cover in sprayed plots. We found that Pivot soil had greater amounts of carbon than Native soil. In 2020, we planted a total of three new strip plots in two new sites in Kearny County, Kansas, with the intent to evaluate which of three different frames worked better for seed counting – A small frame (20 cm x 50 cm), a larger frame (one m x one m), and a three-meter tract of seed row. We found a significant difference between the three frame types, but only the small frame was shown to be inferior to the other two types

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Rights

© 2021 Alonso Barragan-Martinez

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