Here's a national selenium map that the university sent me. As usual I'm right in the middle of "maybe".
http://www.ansci.cornell.edu/plants/...nium/map1.html
Then to make it even more uncertain.
"In addition, all soils are made up of many different minerals which all
interact with each other. The plants ability to uptake those minerals also
plays into that equation.
Instead of asking if your soils are deficient, a better question might be to
ask if your forage contains the proper mineral and then balance your ration
depending on the findings. For example, let's say that you DO live in an
area with suffient SE. There may be other interactions that aren't allowing
the plant to properly uptake the mineral. While your soil might be suffient,
your forage could be deficient.
I would recommend having your forage analysed for mineral content. Easier
said if you make your own hay. Harder to monitor if you purchase your hay
from several sources. Hay mineral content (as well as soil types) can vary
greatly in a short amount of distance.
You could also ask your local vet if they are seeing any mineral imbalances
in livestock in your area."
"