I have a field dominated by broom sedge. Can I use the mature clippings of this grass as a mulch for my vegetable garden? I have read that decaying broom sedge releases a phytotoxin which I obviously do not want in my garden, but it would be very useful if I could cut and harvest this grass once or twice a year to use as bedding for my ducks and chickens and as mulch or a compost component for my garden.
Since most people who ask about broomsedge (Andropogon virginicus) want to get rid of it, this was quite a different question. As you did, a search turned up that it does have allelopathic properties in both the roots and shoots. So, yes, it could cause problems as a mulch in beds where you are planting vegetables from seed. Transplants may not be as affected. In other words, it would work around your tomato, pepper, or cabbage transplants but not over your newly seeded carrots, radishes, or cucumbers.
Organic mulches are often the best choice as they help improve the soil over time. However, I do not know (and it may be unknown) how long those allelopathic residues stay in the soil. Therefore, if you applied the broomsedge mulch this year around your tomatoes, next year when you plant carrots in this same area, there is a potential for those seed-killing residues to still be there.
I studied allelopathy a little and most of what I know about is its effects against germinating weed seeds from either residues or root exudates.
Hope this helps you make a better decision.