Relay Intercropping with Cover Crops Improved Autumn Forage Potential of Sweet Maize Stover

Maize (Zea mays L.) stover is used globally as winter feed for livestock but the nutritive value is low, requiring supplementation. A 2-year randomized complete block study with three replicates at New Mexico State University's Alcalde Sustainable Agriculture Science Center compared sweet maize (Zea mays var. rugosa; maize-alone) with sweet maize relay intercropped with oat (Avena sativa L.; maize-oat) or turnip (Brassica rapa L.; maize-turnip). Relay intercropping had no effect (p > 0.05) on sweet maize stover dry matter (DM) yield and there was no difference in aboveground biomass DM yield of the intercropped species. Turnip aboveground biomass had greater crude protein concentration and 48-h in vitro dry matter disappearance (IVDMD) than oat aboveground biomass. Relay intercropping with turnip improved sweet maize stover IVDMD (443, 439, and 515 g IVDMD kg(-1) for maize-alone, maize-oat, and maize-turnip, respectively, p < 0.0001). Intercropping increased animal gains compared to maize-alone (0.36, 0.52, and 0.59 kg/day for maize-alone, maize-oat, and maize-turnip, respectively, p < 0.02), likely due to provision of additional crude protein. Relay intercropping oat or turnip into sweet maize is viable for improving sweet maize stover for fall forage. In addition turnip, specifically, had a positive effect on stover nutritive value.