More alfalfa management tips

By Gary Sliworsky
OMAFRA Rep.

This is part 2 of a two-part article on cutting management of alfalfa. You may want to refer to the table of Development Stages of Legumes in last week’s article.
The Predictive Equations for Alfalfa Quality (PEAQ) method uses both stage of maturity (vegetative, bud, flower) and stem height to estimate the NDF of the alfalfa in a standing crop. A PEAQ stick has been developed, that incorporates the NDF estimates onto an easy-to-read measuring stick, which can be used in the field.
For beef cow hay, where yield and persistence are greater priorities than quality, cutting after one-tenth bloom (flower) is more appropriate.
With alfalfa-grass mixtures, grasses have the overall effect of increasing fiber levels and lowering protein. Grasses lose quality when heading occurs, so mature grasses can significantly lower quality. A compromise between yield and quality with grasses occurs at “early head emergence from the boot”. Timothy and smooth bromegrass will mature much later than orchardgrass and reed canarygrass, but are less tolerant to frequent cutting schedules.
Subsequent second and third cuttings of alfalfa may be in intervals of approximately 30 days (mid-bud) to 40 days (early flower) or more, depending on whether the goal is high quality or maximum persistence and yield.
Frequent harvests with short cutting intervals of less than 35 days puts stress on alfalfa that can reduce winter survival and first-cut yield the following year. Conversely, a long interval between cuttings will rebuild plant reserves and enhance winter survival.
Harvesting before the “Critical Fall Harvest Period ” allows the plants to regrow and build sufficient root energy reserves for winter survival and persistence, as well as vigorous spring growth and good first cut yields. The Critical Fall Harvest Period is approximately 6 weeks long and varies with location. Refer to Figure 3-4 of Publication 811 “Agronomy Guide” for a map detailing the Critical Fall Harvest Period in your area.
The risk of alfalfa winterkill increases by harvesting during the Critical Fall Harvest Period, and should be weighed against the immediate need for forage. Yield sacrificed by not harvesting during this period is usually easily regained in first cut yield the following year. Cutting before this period can also enhance dandelion control since the alfalfa has time to canopy before dandelions make their autumn comeback.
After a hard fall frost, alfalfa can be harvested without lowering root reserves, but there are risks. Leaving at least 6 inches of fall growth will aid in catching snow, which insulates the soil from cold temperatures. The stubble also helps alfalfa plants survive ice sheeting by protruding through the ice, allowing the movement of air for respiration. Unlike grasses, fall regrowth of alfalfa does not cause “smothering,” but ice sheeting does.