Soybean where?

 “You cannot grow soybean in Scotland”, was the advice recieved by Scottish researchers. Without evidence to support the conclusion, and like TRUE researchers we engaged optimistic seed suppliers to acquire the most suitable genotype. Driven by our interest in elite-rhizobia and -arbuscular mycorrhizal fungi (AMF) inoculum, we established a plot scale trial using cv. ES Comandor.

Prior to sowing, the untreated (no fungicide) seeds were infected with one of three different Bradyrhizobia inocula. Additional treatments included an AMF inoculum with each bradyrhizobia treatment. Normally AMF inoculum is only available for delivery on small horticultural scales. However, recent advances with PlantWorks Ltd., have enabled production of AMF inoculum at large arable scales. Control treatments included ‘no inoculum’ and ‘AMF only’ seed treatments.

The video associated with this article shows the experimental plots. The pale green and less dense ‘no inoculum’ and ‘AMF only” seed treatments are clearly visible as distinct from the darker  green and larger  plants of the ‘bradyrhizobia only’ and ‘bradyrhizobia plus AMF’ seed treatments. At the end of the video a graph is shown detailing the summarised dry matter yield data, which were obtained from harvested as whole crop forage (WCF). The potential per hectare dry matter yields are estimated as 8.1 and at 11 t ha^-1 for the ‘bradyrhizobia only’ and ‘bradyrhizobia plus AMF’ treatments, respectively. These are standardised dry matter yields for a plant density of 72 plants m².

The promising ‘Bradyrhizobia plus AMF’ yield was achieved despite sowing late (mid-May), and on the Scottish north east coast at the Hutton’s Balruddery Farm. The yield is currently being analysed to assess its value as an animal feed. Assessments will also extend to estimates of biological nitrogen fixation (nitrogen obtained by the plants from air), and the diversity of the Bradyrhizobia isolated from root nodules. It was curious that untreated control plants were also nodulated, though the nodules were smaller and fewer in number. 

Future trials plan for earlier sowing, and with an intercrop of wheat to try and maximise WFC feed values.