Those pictures and my limited experience with sunn hemp are from a university research farm. An early season insecticide was still used (an issue with reductionist research that I won’t get into here). Nodulation seemed decent, but this was the first year so I don’t really have any comparison to say it was good or bad. Insect activity in general was massive relative to the no cover crop plots. There were several other species in the mix that flowered- buckwheat, cowpeas, brown mustard, and phacelia. This was in 60″ row corn so there was plenty of sunlight to grow a big cover crop.