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Open Access Knowledge and Scholarship

Date of Award

12-2021

Culminating Project Type

Thesis

Degree Name

Geography - Geographic Information Science: M.S.

Department

Geography and Planning

College

School of Public Affairs

First Advisor

Kirk Stueve

Second Advisor

Jeffrey Torguson

Third Advisor

Michner Bender

Fourth Advisor

Eric Fuller

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Keywords and Subject Headings

Crop Productivity, Remote Sensing, Soil Zonation, Hierarchical Multiple Regression, Ordination, Vegetation Indices

Abstract

Accurate and timely assessment of within-field crop vigor heterogeneity is essential for detecting field-wide crop productivity and yield, contributing to improvements in the management of corn fields. Yet, studies designed to explore the spatial heterogeneity of crop vigor in corn over different productivity zones, where soil nutrient characteristics are known to limit crop productivity during the growing season, as yet been reported. We assessed whether changes in temporal weather conditions within a growing season, contribute to crop vigor variability. Furthermore, we evaluated whether within-season changes in precipitation and temperature contribute to variable nutrient concentrations within different productivity zones. More so, we utilized random forest regression to calculate the relative importance of predictor variables to crop vigor variability. We then employed hierarchical multiple regression (HMR) to build several regression models to determine whether the collinearity of variables (soil characteristics) showed a significant improvement in the R2 i.e., the proportion of explained variance in crop vigor response. The principal component analysis (PCA) was employed to find components that express as much of the inherent variability of the complete data set as possible as well as, to plot how variables map relative to field productivity or management zones. We inferred that, changes in precipitation and temperature during the growing season influence soil nutrient concentrations within productivity zones especially, potassium, calcium, nitrogen, phosphorus, and magnesium. We hypothesize that, significant and yet subtle crop vigor differences can be observed within field productivity zones attributed to the heterogeneity of soil macro nutrient concentrations within corn fields, using the combined utility of remote sensing and hybrid statistical approaches. Thus, aiding farmers to ascertain, early season, whether they will obtain a poor harvest or not, improve on soil nutrient use efficiency, and field management practices to ensure a bumper harvest.

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