Biological Systems Engineering, Department of

 

First Advisor

Dr. Yufeng Ge

Second Advisor

Dr. Derek M. Heeren

Date of this Version

Fall 11-26-2021

Document Type

Article

Comments

A DISSERTATION Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Doctor of Philosophy, Major: Biological Engineering, Under the Supervision of Professors Yufeng Ge and Derek Heeren. Lincoln, Nebraska: November, 2021

Copyright © 2021 Jasreman Singh

Abstract

Increasing pressure on food production, both in terms of quantity and quality, has called for intensification and modernization of the agricultural sector. The “Internet of Things” (IoT) is a highly promising technology capable of advancing agricultural operations. The IoT-based real-time monitoring of soil water status and crop canopy temperature in maize and soybean could potentially improve irrigation efficiency, leading to the profitability of field crop production and conservation of natural resources. The overall goal of the work presented here is to design, develop, and evaluate the unmanned aerial system-based wireless sensor system (UWSN) for the purpose of irrigation management by real-time monitoring of soil water content and crop canopy temperature. Four specific objectives were identified: 1) assess soil structure and texture effects on soil water content measurements using a capacitance-based electromagnetic sensor, 2) develop upper (water-stressed) and lower (non-water stressed) baselines for the quantification of crop water stress index, 3) evaluate the performance of a sensor-based irrigation decision support system (managed by soil water and plant feedback), and 4) design and validate a UWSN system with the airborne data mule deployed on the unmanned aerial vehicle (UAV) and the stationary sensor node stations on the ground. High precision in soil water content was reported in undisturbed soil structure while the uncertainty in the estimation of soil water depletion (Drw) was low. The parameters ΔT (crop canopy temperature differential) and Drw are related after a Drw threshold are attained for maize and soybean. The sensor-based irrigation treatment yielded higher irrigation water use efficiency in comparison to the conventional treatment for maize and soybean. The UWSN system communicated effectively with the sensor node stations when the UAV maneuvered over the vicinity (within 30 m height and 40 m radius) of the sensor node stations. Future studies aiming to investigate the proposed UWSN system for irrigation management under different climatic conditions would strengthen the practical adaptability of this design and may signal new research opportunities.

Advisors: Yufeng Ge and Derek Heeren

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