Global oil yields: Have we got it seriously wrong?

Up to now, most oilseed crop specialists have assumed that one metric ton (MT) per hectare (1MT/ha) was a pretty good ballpark figure for average oil yields from annual oilseed crops such as canola or sunflower. Of course the precise figure varies somewhat depending on the crop variety, climatic zone, and agronomy. Hence, spring-sown canola has quoted yields of about 0.6 MT/ha of oil in the Canadian prairies, whereas high-input, autumn-sown canola/rapeseed varieties in milder European climates average something closer to 1.4 MT/ha. Soybean has lower seed oil content, but it still manages about 0.5–0.6 MT/ha. Hence, the globally averaged oil yield from temperate crops is generally quoted at more or less 1 MT/ha. Thanks to improved varieties and agronomic practices, these estimated yields have increased slightly over recent decades but have not strayed too far from that magic figure of 1 MT/ha (see Table 1).