Feb. 1, 2011

The recent snows blanketing much of the state may be a headache for growers but they’re a benefit for the alfalfa crop.

Alfalfa loves snow. In fact, nothing can increase the chance of alfalfa surviving winter better than a thick blanket of snow.

Moderate weather last fall allowed alfalfa plants to harden well for winter, leaving them with a high concentration of nutrients and a low concentration of water in their roots. This winterized condition enables alfalfa crowns and roots to withstand temperatures as low as 5° above zero.

This may not sound all that cold, but remember that soil temperatures don’t get as cold as air temperatures. When soil is covered with a blanket of snow, this snow acts like a layer of insulation protecting the ground from bitter cold temperatures. Plus, it reduces the rate that soils and alfalfa roots dry out. This is why alfalfa can sustain more injury in winters with little snow cover than in those with a layer of snow, especially if soils are dry.

Of course, management practices in the fall influence the effect of snow on your alfalfa. Tall stubble provides some insulation value and will catch more snow.

Also, avoiding alfalfa harvest during the so-called risk period from mid-September through mid-October helps alfalfa roots winterize well by building up nutrients and reducing water content.

You may not like how snow disrupts your daily routine, but remember how valuable it can be for your alfalfa’s winter survival.

Bruce Anderson
Extension Forage Specialist