>Also there have been several articles in Science News in the past year which
>reported on the effects of excess nitrogen. It seems to push toward weedy
>species (from native species to such invaders as quack grass, for example).
Although of course nutrient deficiency (particularly N,P,K,S) is a far
more common cause of the loss of more productive species leading to the
invasion of "weeds".
Stuart Brown.
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