Complete: Factors influencing crown size and the implications for crown tare

Timescale: 2004 - 2008
Project Lead: P Jarvis, G Milford and M Armstrong
Project Sponsor: British Sugar and BBRO

Project Summary

The crown tares of delivered beet have large financial implications for both grower and processor. Their lower concentrations of sugar and higher concentrations of amino-N, potassium and sodium in the crown affect the efficiency and cost of sugar extraction in the factory and, because growers are now paid for part of the delivered crown tare, very low tares mean a potential loss of income if beet are over-topped leaving potentially deliverable yield in the field.

Main Objectives

The crown is, anatomically, the compressed stem of the plant (Fig. 1). The amount left on the delivered beet (the crown tare) will depend on how large the original crown was (the biological crown size), and the proportion removed by the topping mechanism during harvesting. The effectiveness of topping primarily depends on harvesting conditions and how the machines are set up and operated. But it will also be influenced by the size of the biological crown and its height above the soil - which are not necessarily correlated. Improperly adjusted harvesters machines, could result in large or high crowns being under-topped, and small or low crowns being excessively topped. Crown height is also likely to influence the susceptibility of the beet to frost. It has been shown that frosts are more likely to damage the crowns of beet than the main part of the storage root within the ground, especially when crowns stand proud of the ground and beet are stored in the field and harvested late.

Outcomes / Key Message For Growers And Industry

Under review
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BBRO is a not for profit making company.
We are set up jointly by British Sugar plc and the National Farmers' Union.

British Sugar
National Farmers' Union