Hi there. I'm a Scandinavian so sorry about the English. Not really awesome at chemistry on another language but here it goes.
I'm interested in understand why phosfates bind so much better then nitrogen when it comes soil. It's well known that phosfates make more or less insoluable molecules with for instance Al or Fe. Phosfate can continue developing a negative charge (when it comes to C.E.C.) by amongst others bind to Iron-hydroxides. But Nitrate doesn't. Nitrate on the other hand is very mobile, hardly any electrostatic forces that bind it and is more or less washed out of the earth unless plants take it up.
Now looking at the two molecules they are fairly similar. PO43- and NO3-. Nitrate will even hold a far higher E.N. so why doesn't it react with anything? I read something about it being about a shared charge, were phosfate 5/4 = 1.25 and nitrate 5/3 = 1.66
Cheers