Relay Intercropping with Cover Crops Improves Fall Forage Potential of Sweet Corn Stover.

Small landholders globally must consider all options to produce more food with less land. Crop residues, such as maize (Zea mays) stover after grain harvest, are used throughout the world as an economical winter feed source for livestock. In two years at New Mexico State University's Alcalde Sustainable Agriculture Science Center, sweet corn (Zea mays) was left intact (corn-alone) or relay intercropped with oat (Avena sativa; corn-oat) or turnip (Brassica rapa; corn-turnip) and grazed in the late autumn. Each year the test was a randomized complete block with 3 replicates. Crude protein (CP) and in vitro dry matter digestibility (IVDMD) of turnip topgrowth was higher than oat topgrowth (119 and 186 g CP kg^-1 for oat and turnip, respectively, P < 0.001, and 422 and 623 g IVDMD kg^-1 for oat and turnip, respectively, P < 0.001). Relay intercropping turnip improved sweet corn stover IVDMD across ear, leaf, and stalk components, averaging 443, 439, and 515 g IVDMD kg^-1 for corn-alone, corn-oat, and corn-turnip, respectively (P < 0.001). Relay intercropping with oat or turnip increased cattle average daily gain over grazing corn stover alone (0.45, 0.54, and 0.54 kg d^-1 for corn-alone, corn-oat, and corn-turnip, respectively, P < 0.02. Additional research is needed to determine if the same effect of digestibility improvement by relay intercropping with turnip in sweet corn can occur with corn grown for silage or grain or other species using turnip or other brassica species.