Harvesting the Cereal Nurse Crop Early

Alfalfa winterkill this spring was worse than anticipated across the province, forcing many to reseed significant acreage. Where a cereal nurse crop is used to establish a new alfalfa seeding, the nurse crop will provide some early season weed control and additional forage when harvested as silage. However, the nurse crop has the potential to provide severe competition to the underseeded alfalfa crop resulting in reduced establishment. A nurse crop can also reduce the feed quality of the first-cut if harvested late.

Harvest As Silage Or Grain?
Whether the nurse crop is harvested as silage at the late-boot to early-heading stages, or as grain in August will largely be determined by the relative need for feed or straw. Given the high soil moisture levels this spring, most new alfalfa seedings are well established. However, lush cereal growth is likely to provide intense competition to the new seedings. If forage feed is needed, removing the nurse crop early 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.

Harvest Early For Forage Quality
From a feed nutrient 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. This is usually 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. However, New Liskeard Campus, University of Guelph research demonstrates that as cereal maturity progresses from the boot stage to the milk stage, the in-vitro digestibility drops from approximately 80% to 60%, crude protein drops from above 17% to 10%, while Acid Detergent Fibre (ADF) increases by about 20 percentage points. 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 plant moisture content drops too low for proper fermentation.

Cereal grains mature rapidly around the heading stage. Therefore, harvest of a cereal nurse crop as silage should begin slightly ahead of the harvest maturity stage desired.