Three essays on on-farm precision experiments

Edge, Brittani Kimberlyn

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https://hdl.handle.net/2142/117729 Copy

Description

Title

Three essays on on-farm precision experiments

Author(s)

Edge, Brittani Kimberlyn

Issue Date

2022-10-06

Director of Research (if dissertation) or Advisor (if thesis)

Bullock, David S

Doctoral Committee Chair(s)

Bullock, David S

Committee Member(s)

• Paulson, Nicholas D
• Irwin, Scott H
• Mieno, Taro

Department of Study

Agr & Consumer Economics

Discipline

Agricultural & Applied Econ

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• precision agriculture
• agricultural experiments
• electrical conductivity
• data processing
• on-farm precision experiments
• management zones

Abstract

This dissertation investigates three different topics related to on-farm precision experiments OFPE). These types of agronomic trials are becoming more popular with increased equipment availability and interest from farmers. Rather than small-plot trials or strip trials used in past research, OFPE cover the whole field and, thus, the soil variation that is occurring across the field. There are clear advantages of OFPE, but due to the newness of the field, there are questions about how to design and manage these trials. Currently, individual researchers and research projects are defining protocols for OFPE, but not all of their experiences and findings are shared. Additionally, OFPE follow a long history of on-farm experimentation and precision agriculture research on topics such as management zones. That literature did not have access to field-scale trials like OFPE but was often working with yield or soil maps. Datasets from OFPE allow us to revisit topics in the management zone literature with improved data from a variety of field and weather years. Each of these chapters investigates a question relevant to OFPE implementation or a question answered with OFPE data. In the first chapter, I investigate the impact of a specific type of trial implementation error in OFPE data. This error is called harvest misalignment or treatment mixing and occurs when the combine passes through more than one treatment during harvesting. This results in a yield measure that is the average yield from two different treatments. Using a simulation study, this chapter estimated the economic cost of harvest misalignment as seen from the misestimation of the optimal treatment rates from an OFPE. Additionally, I evaluate the use of a potential data processing method to remove areas with harvest misalignment from the data before calculating the optimal input rates. Results show that harvest misalignment does induce profit losses from the estimation of the optimal input rates, and some types of harvest misalignment cannot be addressed through the data processing method proposed. Researchers conducting OFPE should be aware of harvest misalignment, designing trials and communicating with farmers to minimize this error in the trial data. In the second chapter, I evaluate the use of electrical conductivity (EC) for defining seed and nitrogen management on corn. EC is a measure of the soil's ability to conduct electrical current and is often correlated with clay content or moisture in the climate of the Midwest. Data from 33 OFPE are used to evaluate whether EC maps can help define profitable seed and nitrogen management. The results show that EC was not profitable for these fields with all but two fields showing less than five dollars per acre profit increases from moving to VR application from UR application. In the third chapter, I investigate the relationship between yield level and optimal nitrogen and seeding rates. Much of the past literature posits that the yield level or yield potential of the soil determines the nitrogen or seeding rate needed. This led to yield maps being used to delineate management zones and variable selection for management zones through yield prediction. From microeconomic theory, it can be shown that using yield prediction to define management should be suboptimal. Using 38 OFPE to define optimal seed and nitrogen management based on two different yield variables, I found that the yield-based management was not profitable over a uniform rate for the majority of fields and the yield level did not have a clear relationship with the optimal rates. This result highlights the need to refocus the management zone literature from yield to finding the characteristics that change the marginal yield response to the managed inputs such as seed and nitrogen.

Graduation Semester

2022-12

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 Brittani Edge

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