Relay Cropping Practices That Improve Performance of Italian Ryegrass As a Cover Crop after Silage Corn.

Winter cover crops after silage corn can improve the quantity and quality of home-grown feed on dairy farms, reducing feed imports and possibly also nutrient losses. Establishing cover crops into juvenile corn in spring can improve fall N recovery and spring yield. We planted a series of three- year experiments to test relay cropping practices on the host crop (corn) and the cover crop (Italian ryegrass). The study was conducted under maritime conditions with mild wet conditions in southwest BC, Canada. The relay crop had very little impact on corn yield if planted when corn was at 6-9 leaves, but earlier planting reduced corn yield by about 0.5 t DM/ha. At corn harvest, relay crop biomass varied from 0.3 to 1.2 t DM/ha with greater biomass occurring under lower corn populations (55,000 vs 65,000 or 75,000 plants/ha), earlier planting (3-leaf stage of corn) and earlier corn harvest (by 7 to 18 days) Fertilizing the relay crop in March (50 kg N ha) doubled its late April yield to approx.. 1.6 to 2.4 t DM/ha. We found that of 40-60 Italian ryegrass varieties evaluated over three years, tetraploid biennial types were consistently better relay crops than diploid biennials or Westerwold annual types. We hypothesized that the tetraploids biennials had greater tolerance than diploids to Fusarium graminearum.