We’ve previously published a report on using summer cover crops, including sunn hemp, for weed suppression in organic no-till pumpkins. Last fall, a Southern SARE Producer Grant reported results of a similar cover crop mix for fall broccoli production.
Wild Hope Farm, in Chester, South Carolina, ran a two-year trial of sunn hemp, both alone and in combination with various other summer cover crops, including millet, soybeans, and buckwheat.
For sunn hemp alone, there were two termination treatments: tillage and crimping. For the mixes, crimping was the only termination method.
Sunn hemp was more effective at suppressing weeds in combination with other cover crops than alone, but the timing of crimping and the weight of the crimper were important for ensuring complete termination.
When these factors were not properly adjusted, regrowth of the cover crops could become a bigger impediment to yields than the weeds they were meant to control.
Broccoli yields were highest in the combination of sunn hemp and millet.
More information on the project, including a full fnal report, handouts, a slide presentation, and a short video, is available from the Southern SARE Producer Grant webpage.