On research farms on which vegetable crops are studied, there is often a need to aggressively maintain and improve soil health, while also keeping fields ready to be assigned to research projects. We tested a protocol for keeping a Northeast farm in an appropriate condition by alternating a winter cover crop of cereal rye and a summer cover crop of forage sorghum-sudangrass with no tillage. The alternating cycle was flexible for entry points when vegetable researchers finished with an experiment, as well as for exit points to make the ground ready for an experiment. Rye was sown in late September in Geneva, NY with a no-till drill and allowed to grow to anthesis in May. Sorghum-sudangrass was sown in mid-June with the no-till drill. We tested how much nitrogen fertilizer was needed to obtain a desirable amount of growth (3 tons/acre dry mater) in the sorghum- sudangrass. The trial was done in four fields using 0, 20, 40 and 60 lb N broadcast on the rye residue at planting. The highest rate is as much as our farm would agree to invest in a cover crop, but also below forage-crop recommendations. The biomass when growth stopped due to cold (Sept 18) responded strongly to nitrogen. Without nitrogen, the biomass was only 0.5 T/ac. At 60 lb/ac, the biomass ranged among fields from 2 to 4 T/ac. Nitrogen limitation was also assessed using a SPAD chlorophyll meter. The leaves in the 0, 20 and 40 lb/ac were yellow (SPAD 22-28), with the top N rate notably greener (SPAD 30-35). The fully green control had a SPAD value of 40. The cover crop rotation kept the field in a condition where is could be prepared to being a research project with about a month’s advance notice. However, to get sufficient growth of the summer cover crop, additional nitrogen is needed. This farm is on a high-fertility silt loam, but with low organic matter from repeated research trials. In that situation, at least 60 lb/ac of actual N is needed for the cover crops to meet biomass expectations.
