Originally Posted by Smallaxe
Actually it makes sense that when dealing with such a volatile element as N(in most any form) that the likelyhood of it remaining stable through a typical winter is almost nill...
Let's say the ground freezes solid about 6" - a foot down, before snow cover hits... We get a huge storms with one or two feet of snow that stays the rest of the winter...
What happens under the snow??? What happens when the snow melts in the Spring???
Once you think about the dynamics of the living world, you don't look at N being 'preserved through the winter' the way hamburger is preserved in the freezer...
I really would like an answer to those 2 questions...
Studies have shown over and over that soil N content is usually very stable in frozen soils.
In the fall, nitrates tend to move down in the soil profile with increased rainfall, then move up with the freeze/thaw of late fall, stay stable in mid-winter, then move up with spring freeze/thaw cycles, and back down with rain and snow melt. Nitrate really follows the water.
Denitrification reactions are inhibited by cold temperatures in fall/winter/spring, do very little nitrate is lost.
Ammonium tends to hang around on CE sites and very little is converted to nitrate in cold weather because the weather is too cold for amped activity of those microbes. This is partially the reason that anhydrous ammonia can be used as an ag fertilizer and is applied in the cooler weather.
Once you look at the dynamics of the living world, you better understand why applications are done in a particular manner.