Yields of Corn Silage Fertilized with Manure and Grown with Legume or Non-Legume Companion Crops.

While growing companion crops with corn can reduce soil and nutrient loss from cropland, they also can affect corn silage yields. In a four-year study in southern Wisconsin, no-till corn was grown with herbicide-suppressed kura clover or with June-interseeded red clover followed by one year of clover production. These rotations were compared to continuous corn grown with June-interseeded Italian ryegrass, September-seeded winter rye, or no cover crop. Each year, manure slurry was applied on a phosphorus basis and continuous corn plots received additional fertilizer at planting to supply 180 kg/ha of available nitrogen. In 2003 (dry summer), dry matter yields of corn silage were greatest with red clover (23.0 Mg/ha) and lowest with Italian ryegrass (18.4 Mg/ha). In 2004 (wet spring and cool summer), corn silage yields with kura clover (20.0 Mg/ha) exceeded other systems (16.1 to 17.8 Mg/ha). In 2005 (dry spring and early summer), corn silage yields with red clover (22.1 Mg/ha) surpassed other systems (14.1 to 16.3 Mg/ha). In 2006 (wet spring, uneven stands), corn silage yields were greatest with kura and red clovers (16.0 Mg/ha, respectively) and lowest with Italian ryegrass (12.2 Mg/ha). Spring vs. fall manure application did not influence corn yields. By late October, growth of companion crops was greatest for Italian ryegrass (0.9 to 2.0 Mg/ha), while growth of winter rye (2.9 to 5.7 Mg/ha) exceeded other companion crops by late April. Overall, corn silage yields were usually enhanced by clovers, depressed by Italian ryegrass, and not influenced by winter rye.