City Research Online

Abstract

Current agricultural practices are increasingly adopting sustainable methods to achieve high crop yields and meet market demands. However, the excessive use of water and fertilisers has led to issues such as food insecurity and climate change. The over-application of plant nutrients increases food prices and results in unused fertilisers contributing to harmful greenhouse gas emissions, which affect the ozone layer. This raises the question: why are excessive amounts of water and fertiliser wasted despite the availability of agricultural sensors and technologies that aim to improve sustainability? This paper critically examines the underlying theory and technology behind these practices to identify their challenges and limitations. The review focuses on the shortcomings of current soil theories, covering soil physics, electrical properties, and factors influencing soil characteristics. Additionally, this paper discusses various techniques used to measure the electrical properties of soil, including traditional methods, capacitive sensors, time-domain and frequency-domain reflectometry, amplitude-domain reflectometry, and broadband dielectric spectroscopy. The challenges and limitations of these techniques are also explored. Furthermore, the paper addresses the theory and challenges of electrical property measurement techniques at the system level, analysing the injection, load, and output stages to identify the difficulties in each part.

Publication Type:	Article
Additional Information:	© 2025 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)
Publisher Keywords:	Broadband dielectric spectroscopy, Capacitance, Electrical conductivity, Fertilisers, Frequency domain reflectometry, Impedance, Moisture, Resistance, Soil sensor, Temperature, Time domain reflectometry, Water tension
Subjects:	S Agriculture > S Agriculture (General) T Technology > TK Electrical engineering. Electronics Nuclear engineering
Departments:	School of Science & Technology School of Science & Technology > Engineering
SWORD Depositor:	Symplectic Administrator

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