Soybean farming leads to devastating impacts on forests, such as the Amazon. It destroys soil, making it harder to grow crops in the future. It provides incentives for governments to build large transportation systems through forests in order to better facilitate transit. This obviously leads to the destruction of the habitats of non-human life.
I quickly googled these two articles that provide information about the impacts of soy production: http://ipsnews.net/news.asp?idnews=3365
I think we must mobilize fellow vegans to start using alternatives, such as rice milk or almond milk.