It's mentioned in the article, but doesn't go into detail about why it hasn't caught on
> Continued problems with vinasse-dumping marred the sugar-ethanol industry’s environmental image, even as specialists encouraged repurposing the nitrogen-heavy byproduct as a fertiliser. Today, compliance with anti-dumping legislation is still not effectively enforced.
> Continued problems with vinasse-dumping marred the sugar-ethanol industry’s environmental image, even as specialists encouraged repurposing the nitrogen-heavy byproduct as a fertiliser. Today, compliance with anti-dumping legislation is still not effectively enforced.