Harvesting The Cereal Nurse Crop As Silage

There are good arguments for and against the use of a cereal nurse crop when seeding down alfalfa. While the cereal nurse crop provides some early season weed control and additional forage, it also has the potential of providing severe competition to the underseeded alfalfa crop. As well, the stage of maturity of the cereal crop at harvest is critical in determining the yield and quality of the cereal crop when used as forage.

The nurse crop can either be harvested as silage at the late-boot to early-heading stages, or as grain in August with the straw baled.  This year, most new alfalfa seedings are well established, but lush cereal growth is likely to provide intense competition to the new seedings. Consequently, if forage feed is needed, removing the nurse crop as silage may be the best option. Removing the cereal competition early in the summer will also allow the alfalfa to establish quickly, giving the opportunity of a second cut by summer’s end.

From a feed value stand point, when harvesting the crop as silage, best results are obtained when the cereal crop is harvested early. The ideal time to cut the cereal nurse crop is at the boot (just before heading) to early-heading stage, which usually is about 50 days after planting. It is often tempting to delay the harvest of the nurse crop given that dry matter yield of the cereal increases by about 50% from the boot stage to the milk stage. But, research at New Liskeard campus, University of Guelph demonstrated that as cereal maturity progresses from the boot stage to the milk stage, the in-vitro digestibility of the crop drops from approximately 80% to 60%, crude protein drops from above 17% to 10%, while ADF increases by about 20%. Once the cereal crop reaches the milk stage and beyond, it becomes high in fibre and low in digestibility, dropping significantly in feed value. Additionally, a cereal nurse crop at the late-milk stage or dough stage is difficult to ensile since the moisture content of the plant drops too low for proper fermentation.

As for harvest management, cereal grains mature rapidly around the heading stage. As such, harvest of a cereal nurse crop as silage should begin slightly ahead of the harvest maturity stage desired.

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