Graduate Studies

 

First Advisor

Jay Parsons

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Agricultural Economics

Date of this Version

12-5-2023

Document Type

Dissertation

Comments

Copyright 2023, Jessica L. Windh

Abstract

This dissertation is a compilation of 5 chapters culminating in a bioeconomic model of the interactions between an integrated crop-livestock system and native rangeland grazing system. The model is developed using data from the eastern Sandhills of Nebraska, a location where cropping systems of Eastern Nebraska border one of the last intact grasslands remaining in North America. The first chapter introduces the reader to the systems that will be modeled in the dissertation. In Chapter 2 we used a linear regression to model grassland biomass production as a function of climatic variables; we were unsuccessful in modeling season-long production in this way. In Chapter 3 we again modeled grassland biomass production, but this time as a mathematical function using the Gompertz growth curve equation. Cereal rye production was modeled in Chapter 4 following methodology from Feyereisen et al. (2006) and Coufal (2019). Production numbers were substantially lower than what was modeled by Coufal (2019) at a study site 200 miles away, so more investigation is needed to validate the conclusions of Chapter 4. In Chapter 5, all previous chapters culminate into the bioeconomic model. Cereal rye grazing is coupled with rangeland grazing to determine 1) the reliability of cereal rye as a feed resource, and 2) the benefits derived by the rangeland system from having a cover crop delay the start to grazing. We found that cereal rye provided 19 to 27 days of grazing and that it replaced the need for hay feeding in 4 of 9 years. Furthermore, by delaying rangeland grazing by 5 days, we can see returns to the delay of 400 to 1000%.

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