Precision Agriculture

, Volume 14, Issue 2, pp 215–223 | Cite as

The most common errors of capacitance grain moisture sensors: effect of volume change during harvest

  • M. Csiba
  • A. J. Kovács
  • I. Virág
  • M. Neményi


The objective of this study was to investigate the inaccuracy of a capacitance moisture sensor mounted on a combine harvester based on the datasets of six consecutive years. Variation of sensed volume is a major cause of measurement error for a capacitive sensor. The percentage of the sensed volume occupied by grain changes continuously by filling and emptying of the grain bin, which causes a large fluctuation in sensor output during on-the-go moisture sensing. At the beginning of the bin filling process when the grain bin is empty, under-measures were recorded and when it is approximately 60 % full, large over-measures are observed compared to the actual moisture values. This effect mainly influences the precision of the recorded site-specific moisture values and causes inaccurate yield maps. To assess the effect of varying sensed volume content during harvest operation, a bin level transmitter sensor was mounted on the top of the grain bin to continuously measure the height of the grain. A clear correlation between the actual amount of material (available space) in the grain bin to the bias from the standard moisture was demonstrated. The coefficient of determination was R2 = 0.86 for corn (Zea mays L.) and R2 = 0.87 for winter wheat (Triticum aestivum L.). By using equations generated from the datasets of consecutive years (2008, 2009 and 2010), an effective post-correction method for the recorded data is proposed.


Capacitance sensing Grain moisture Harvest 

List of symbols


Distance (m)


Voltage (mV)


Grain bin fill (%)


Grain bin coefficient


The highest difference from standard in negative range


The highest difference from standard in positive range



The research was financed in the framework of the TÁMOP-4.2.2. B-10/1-2010-0018 project entitled “Talentum-Improvements in the conditions available for encouraging talented students at the University of West Hungary” with funds from the European Union and the European Social Fund.


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Copyright information

© Springer Science+Business Media New York 2012

Authors and Affiliations

  • M. Csiba
    • 1
  • A. J. Kovács
    • 1
  • I. Virág
    • 1
  • M. Neményi
    • 1
  1. 1.Faculty of Agricultural and Food SciencesInstitute of Biosystems Engineering, University of West HungaryMosonmagyaróvárHungary

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