Outcome of Sorghum-sudangrass as a cover crop for organic no-till vegetable production and as a hey crop for the organic market

The development of organic and conservation tillage-based vegetable production systems will offer growers in the United States new economic opportunities and promote resource conservation. The purpose of this research project was to assess the impact of including a summer crop that serves as both cover crop and marketable hay crop in an organic fall vegetable production system. Sorghum sudangrass [Sorghum bicolor (L.) Moench X S. sudanense (Piper) Staph] is commonly cultivated as a forage crop for grazing, hay, or silage and has the potential to produce abundant biomass, suppress weeds through physical and chemical interference, and decrease soil compaction as a summer cover crop. Field studies were conducted to determine the effects of sorghum sudangrass mowing frequency and biomass removal as hay on cover crop biomass production, weed suppression by cover crop residues, and cover crop re-growth in a subsequent cabbage (Brassica oleracea L. var. capitata) crop under conventional and no-till organic management. Small plots of cabbage were planted as a test crop in mow-killed sorghum sudangrass residues to determine if sorghum sudangrass mulch reduced cabbage head weight and time to maturity. Results suggest that harvesting a sorghum sudangrass hay crop early in the summer growing season did not affect suppression of broadleaf, annual weeds by the cover crop mulch in a fall cabbage crop. In this study, however, the presence of sorghum sudangrass led to reduced cabbage head weight. Sorghum sudangrass may not be suitable as a cover crop immediately prior to conventional or no-till organic fall cabbage production because of its capacity to regrow following mechanical kill by mowing and its ability to produce chemicals that may harmful to direct-seeded and transplanted vegetable crops. Economic analysis indicates that harvest and sale of a single cutting of hay from a sorghum sudangrass summer cover crop can provide additional income to a farm enterprise. 

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