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Sensors 2016, 16(12), 2196;

Nondestructive In Situ Measurement Method for Kernel Moisture Content in Corn Ear

College of Information and Electrical Engineering, China Agricultural University, Beijing 100083, China
Key Laboratory of Agricultural Information Acquisition Technology (Beijing), Ministry of Agriculture, Beijing 100083, China
Modern Precision Agriculture System Integration Research Key Laboratory, Ministry of Education, Beijing 100083, China
Author to whom correspondence should be addressed.
Academic Editor: Simon X. Yang
Received: 10 September 2016 / Revised: 25 November 2016 / Accepted: 7 December 2016 / Published: 20 December 2016
(This article belongs to the Special Issue Sensors for Agriculture)
View Full-Text   |   Download PDF [5370 KB, uploaded 20 December 2016]   |  


Moisture content is an important factor in corn breeding and cultivation. A corn breed with low moisture at harvest is beneficial for mechanical operations, reduces drying and storage costs after harvesting and, thus, reduces energy consumption. Nondestructive measurement of kernel moisture in an intact corn ear allows us to select corn varieties with seeds that have high dehydration speeds in the mature period. We designed a sensor using a ring electrode pair for nondestructive measurement of the kernel moisture in a corn ear based on a high-frequency detection circuit. Through experiments using the effective scope of the electrodes’ electric field, we confirmed that the moisture in the corn cob has little effect on corn kernel moisture measurement. Before the sensor was applied in practice, we investigated temperature and conductivity effects on the output impedance. Results showed that the temperature was linearly related to the output impedance (both real and imaginary parts) of the measurement electrodes and the detection circuit’s output voltage. However, the conductivity has a non-monotonic dependence on the output impedance (both real and imaginary parts) of the measurement electrodes and the output voltage of the high-frequency detection circuit. Therefore, we reduced the effect of conductivity on the measurement results through measurement frequency selection. Corn moisture measurement results showed a quadric regression between corn ear moisture and the imaginary part of the output impedance, and there is also a quadric regression between corn kernel moisture and the high-frequency detection circuit output voltage at 100 MHz. In this study, two corn breeds were measured using our sensor and gave R2 values for the quadric regression equation of 0.7853 and 0.8496. View Full-Text
Keywords: corn ear; moisture; nondestructive measurement; high-frequency detection; impedance corn ear; moisture; nondestructive measurement; high-frequency detection; impedance

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Zhang, H.-L.; Ma, Q.; Fan, L.-F.; Zhao, P.-F.; Wang, J.-X.; Zhang, X.-D.; Zhu, D.-H.; Huang, L.; Zhao, D.-J.; Wang, Z.-Y. Nondestructive In Situ Measurement Method for Kernel Moisture Content in Corn Ear. Sensors 2016, 16, 2196.

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