Relay-Intercropping Turnips (Brassica rapa L.) and Oats (Avena sativa L.) into Sweet Corn (Zea mays L.) to Enhance Forage Biomass and Quality.

Small-scale cattle producers in northern New Mexico commonly overwinter their animals on the residue of whatever cash crops they have grown during the previous season. Chile and sweet corn are very commonly grown cash crops in this region, but can only utilize the frost-free period for production. Relay intercropping describes systems in which two crops are grown in the same field, but at different times, and has the potential to increase overall productivity. This study examines cool-season annual forages (oats and turnips) relay interseeded into sweetcorn to enhance the feed value of the corn residue after the sweet corn has been harvested.  Sweet corn was sown at a rate of 7.4 kg ha^-1 in early May. Annual forages were broadcast in mid-July in both years (at 5.2 kg ha^-1 and 109 kg ha^-1 seeding rate for turnips and oats, respectively). Sweet corn harvest occurred in early August each year; and after a killing frost in October, total forage biomass was sampled in early November, prior to grazing. Biomass was partitioned by species and plant part, and quality factors were determined for each component.  Interseeded forages increased the total forage biomass by 43% to 80%. In year one of the study, turnips produced significantly more biomass than oats, but in the second year, turnips and oats produced similar total biomass. In addition, intercropped forages significantly increased crude protein yield. Taken together, the increased biomass and improved quality could translate either into increased average daily gain of cattle, intensified stocking levels, or greater number of grazing days in the season.