Zeolite in the substrate?

I heard a news story on CNN Headline News sometime in the course of the
last week about a wonderful growing medium that NASA had developed to grow
plants on Mars or something.  The stuff had the advantage of being able to
absorb then slowly release nutrients.  They said it would be marketed soon
for farms, and it was hoped that it would stem the fertilizer runoff tide.

I could have sworn they said it was called "Zeolite."  I guess that would
make sense, given Zeolite's reputation for being able to absorb ammonia.

Could this be something that one of the experimenters on the list should
try in a substrate?


P.S.  About the recent discussion of iron . . . a guy who almost became my
brother-in-law (whew! it was close) swore that no matter how much light he
gave his aquatic plants he never had much success till he dropped an iron
nail into his backfilter.  I don't wish to vouch for his credibility,