If short, drought-stricken alfalfa starts blooming, it may be wise to wait until the crop approaches full bloom, then cut it at normal stubble heights, suggest Rory Lewandowski and Mark Sulc, Ohio State University Extension educator and forage specialist, respectively.
Many areas of Ohio are under drought conditions, and some fields are starting to bloom at 4-6” of height. Lewandowski and Sulc point out that alfalfa’s growth slows as it starts to bloom, and stops when it reaches full bloom. Very little tonnage is added after blooming begins. But quality declines more slowly in dry conditions, and waiting until full bloom will let the plants build carbohydrate reserves.
If alfalfa is cut under drought conditions, there is no advantage to raising the cutting height, say the experts. Alfalfa can regrow from axillary buds higher on the stubble instead of from crown buds, but those stems are smaller and produce less yield. So growers might as well harvest alfalfa at the normal height and gain all the yield available.
If livestock are available, producers may want to consider salvaging low-tonnage yields by grazing the crop. But take precautions to prevent bloat. Don’t turn hungry livestock into alfalfa, don’t graze dew-covered alfalfa, make sure stocking density is high enough to prevent animals from selectively grazing plant tops and consider using a bloat preventative.
Lewandowski and Sulc say drought impacts alfalfa three ways:
- When plants are moisture-stressed in the first 14 days after a cutting, the number of basal buds and stems per plant is reduced.
- The stem internode length is reduced under moisture stress, thus the blooming seen in plants 4-6” tall.
- Leaf size and growth rate are reduced, although to a lesser degree than stem growth. The result is that the leaf-to-stem ratio and forage quality are higher than under normal growing conditions.