Under år 2007 observerades dålig etablering och svag tillväxt hos blålupin i ett odlingssystemsförsök i Bollerup, Skåne. Förfrukten var hampa. I led med sockerbetor som förfrukt var blålupinetableringen god och visade inga tecken på försämrad uppkomst eller tillväxt. Samma iakttagelse gjordes år 2008. En misstanke väcktes då om att baljväxters etablering och tillväxt blir tillbakasatt av att odlas I en växtföljd med industrihampa på grund av dess allelopatiska ämnen.

Hemp is an annual energy crop that fits very well in Swedish crop rotations. It is an interesting crop with many benefits, for example its ability to establish a large quantity of biomass in one year. Hemp is easy to grow and out-competes unwanted weeds through its aggressive growth pattern without the need for pesticides. Interest in growing hemp and other energy crops is currently decreasing, apparently because of high grain prices. These high prices give a higher net profit that we believe could partly cover the cost of hemp cultivation, while the hemp in turn would improve the crop rotation and thus repay its debts in the form of increased yields of other crops. The great disadvantage of hemp is the lack of knowledge about spring harvest of the crop.