It certainly does work.

Legumes are good to use as the fix nitrogen. Tares used to be common ( type
of vetch used for horse feed)

We use a similar technique on commercial plantings of tree and shrub whips.
underplant with wheat. It reseeds for the first three years and there is no
need to spray out for weed. The downside it rats so not a good idea in a
small garden



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