Researchers at McGill and AZ State report global increase in phosphorus demand and amount of mined P consumed per person/yr 1961-2007 as linked to increase in meat consumption.  They suggest modification of meat consumption and slowed population growth as a partial solution to rapid exhaustion of this essential non-renewable resource.  See: http://environmentalresearchweb.org/cws/article/news/52298.   Cool video abstract includes nod to P losses in ag systems and livestock systems.