WSU Extension Q&A: When the ground freezes, why don’t the plant’s roots freeze?

Q. When the ground freezes, why don’t the plants’ roots freeze?

A. In the winter, the ground can be frozen, but that means water between the fine soil particles has frozen. The deeper soil profiles are less susceptible to temperature changes than the surface soil. So in winter, deeper layers may be warmer than top layers, and the reverse is true for the summer, when the sun will heat the top layer of soil. Plants suited for cold climates grow roots that extend deeper in the soil to reach liquid groundwater for use in the spring. Also, plants accumulate starches and compounds to lower their freezing points.

Q. Now that people are using electronic devices to find recipes and food preparation information, are there food safety concerns connected with this practice?

A. A recent national study found that about half of the people surveyed used electronic devices such as a smartphone or tablet in the kitchen, but only about one-third of those people wash their hands with soap and water after touching the devices. Electronic devices can be a source of pathogenic bacteria. When using electronic devices in the kitchen, wash your hands after touching them and before continuing with food preparation.

Q. What is neutral detergent fiber, and why is it important?

A. Neutral detergent fiber, or NDF, is the portion of plant cells that includes most of their structural components in plant cells (i.e. lignin, hemicellulose and cellulose), but not pectin. For dairy, NDF is an important measurement because it affects how fast the hay goes through the animal. Higher-quality hay speeds feed movement through the cow, whereas lower-quality hay slows it down. Neutral detergent fiber is measured in percentages. The U.S. Department of Agriculture quality grades for alfalfa hay and their corresponding NDF range: Supreme (less than 34 percent), Premium 34 percent to 36 percent, Good (36 percent to 40 percent), Fair (40 percent to 44 percent) and Utility (greater than 44). These can be determined either by wet chemistry or by using a NIRS (near infrared spectroscopy) machine.

This story was originally published February 26, 2017 at 1:10 PM with the headline "WSU Extension Q&A: When the ground freezes, why don’t the plant’s roots freeze?."