Prediction of various effects of harvest date in sugar beet growing

One crucial decision in sugar beet growing is determining harvest date. This paper focuses on some aspects associated with harvest date which have to be included in a decision support system for sugar beet growing, Firstly, a module was created for dirt and crown tare, mainly based on lutum (or clay) and soil moisture contents. An independent test of the module showed poor results, because fine tuning of harvest machinery has an overriding effect. Secondly, the variation in weather conditions during autumn in Wageningen over a period of 38 years was analysed. The ranges of future root and sugar production appeared to be so wide that early predictions of the day on which the sugar quota are exceeded will not be very reliable. Thirdly, risks of severe frost or heavy rainfall in autumn were assessed, based on the same 38 year data set. The risk of frost damage to unharvested beets proved to be negligible when the crop was harvested before November 10, as advised by the sugar industry. The work described in this study makes the model PIEteR (a field specific bio-economic production model for sugar beet, developed for decision support at field and farm level) more applicable by using its potential to analyse the effects of different years and quota options.