The yield gap in some beet producing countries

The efficiency of an arable crop production system can be expressed as the yield gap, defining the difference between the potential and the actual yield; the larger the gap the less efficient the system. One way to assess the yield gap for sugar beet production is to compare the delivered yield with the yield produced without any farmer-imposed constraint, where the yield of the crop is limited only by the availability of heat, sunlight and water. Official trials designed to produce lists of recommended varieties usually suffer few if any constraints. The Plant and Soil Group of IIRB have collected national yield and recommended variety performance data for a range of beet producing countries over the last decade. These data show that yields are increasing in all countries, some more rapidly than others. They also show that the yield gap is stable in most countries while it is getting wider in others. It is only in the USA that the agronomy seems to be getting more efficient. These results will be discussed in relation to the protocols used for the variety trials and in relation to national yield statistics