Long-term post-harvest field storage of sugar beet (Beta vulgaris subsp. vulgaris)


The post-harvest storage of the sugar beet crop in Sweden occurs in the field. The harvest of roots generally ends along with the month of November, but the processing campaign can continue into February. The loss of quality of the stored roots during this period is economically important. This thesis groups the main mechanisms that results in loss of quality during post-harvest storage in two categories: plant health, and the storage environment. It focuses on the plant health dimension of mechanical properties, and the storage environment dimensions of moisture and temperature. 

The relationship between key agronomic inputs and mechanical properties and storability of sugar beet roots was investigated. Growing season available nitrogen and water were found to have little impact on mechanical properties. The storability of roots was found to decrease significantly when irrigation gave an optimal soil water availability throughout the season. This is likely a result of an interaction with an unspecified dimension of plant health. The quantification of sugar beet root mechanical properties with a traditional handheld penetrometer applied in-field was found to be reliable. It was also found that the methods used in the analysis of mechanical properties could be expanded to include the apparent modulus of elasticity and that fall-tests can be used to assess dynamic impacts. 

The use of a short, intense period of forced ventilation of a sugar beet bulk was found to lead to dehydration of sugar beet roots in a predictable manner. This resulted in increases to sucrose concentrations that would lead to greater gross income. Computational Fluid Dynamics modelling of the temperature within a clamp proved to be possible and insightful. The fluid dynamics within the clamp are important to include in such modelling.


clamp; quality; mechanical properties; handheld penetrometer; forced ventilation; computational fluid dynamics; mass transfer; heat transfer

Published in

Acta Universitatis Agriculturae Sueciae
2023, number: 2023:36
ISBN: 978-91-8046-124-5, eISBN: 978-91-8046-125-2
Publisher: Swedish University of Agricultural Sciences

Publication Identifiers


Thesis on SLU publication database

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Table of contents

List of publications
Terms, Abbreviations, Symbols

  1. Introduction
    1.1 Long-term post-harvest field storage of sugar beet
    1.1.1 Post-harvest field storage system
    1.1.2 Long-term storage
    1.2 Principles of successful post-harvest storage of sugar beet
    1.2.1 Healthy sugar beet roots
    1.2.2 An optimal storage environment
    1.2.3 Summary of principles
    1.3 Swedish conditions
    1.3.1 The natural environment conditions: Climate
    1.3.2 The market conditions: Industry agreement and contracting
    1.3.3 Post-harvest field storage under Swedish conditions
    1.3.4 Long-term storage under Swedish conditions
    1.3.5 The broader conditions
    1.3.6 The research conditions: Applied
  2. Aims and objectives
  3. Methods
    3.1 Experimental design
    3.1.1 Field trials including laboratory testing (Paper I and II, and SSs)
    3.1.2 Modified environment experiment (Paper III)
    3.1.3 Computational Fluid Dynamics modelling (Paper IV)
    3.2 Assessment
    3.2.1 Quantifying quality
    3.2.2 Quantifying mechanical properties
    3.2.3 Measurement of dynamic impacts
    3.2.4 Modified environment conditions
    3.2.5 Mass transfer, water vapour deficit, convective mass transfer coefficients, diffusivity
    3.2.6 CFD model functionality and accuracy
    3.2.7 Economic analysis
  4. Results and discussion
    4.1 Plant health and the long-term post-harvest storage of sugar beet roots
    4.1.1 Agronomic inputs and storability
    4.2 Storage environment and the long-term post-harvest storage of sugar beet roots
    4.2.1 Moisture and mass transfer
    4.2.2 Temperature and heat transfer
  5. Conclusions
  6. Outlook

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