Sorghum sudangrass as a summer coverand hay crop for organic fall cabbageproduction

No-tillage (NT) organic vegetable production presents several economic opportunities for growers in the southeasternUnited States while promoting natural resource conservation. This study was conducted to determine if removal of sorghumsudangrass (SS) cover crop biomass as hay, frequency at which the cover crop is mowed, and tillage affect weed suppressionand head weight of transplanted organic cabbage. Sorghum sudangrass [Sorghum bicolor (L.) MoenchrSorgum sudanense(Piper) Staph.] was planted in May 2004 at Reidsville and Goldsboro, NC, preceding the planting of organic ‘Bravo’cabbage (Brassica oleracea L. Capitata group) in August and September 2004, respectively. SS management systemsincluded: low-frequency mowing with hay removed following the first mowing operation (LFM-H), low-frequency mowingwith hay not removed (LFM), high-frequency mowing with hay not removed (HFM) and a no cover crop control. Twotillage treatments were applied within each management system: conventional tillage (CT) and NT. Under NT conditions,SS mulch generated by LFM offered broadleaf weed control in cabbage similar to that achieved under CT, regardlessof whether cover crop biomass was removed as hay. Mowing with higher frequency reduced SS cover crop biomass by18–33% and reduced weed suppression in NT cabbage. Mowing frequency did not influence the quantity of SS that re-grewin the cabbage crop. SS re-growth contributed to lower head weight in NT compared to CT cabbage in Goldsboro, and cropfailure of NT cabbage in Reidsville. Cabbage head weight was highest when the crop was not preceded by SS in both CTand NT systems (1.6 as opposed to 1.3–1.4 kg head -1). Our findings suggest that the potential for growers to manage a covercrop also as a hay crop does exist; however, SS may not be a compatible cover crop species for organic fall cabbageproduction due to high amounts of re-growth.