Von Liebig was quoted by Marx who, in my view could be counted among the   
environnementalists. This point is developped in a paper coauthored with   
Ms Ferrari and H. Hanusch (Augsburg University, prepared for the   
Georgescu-Roegen Conference, Strasbourg, November 1998  
Marx, Schumpeter and Georgescu-Roegen : Three conceptions of the   
evolution of economic systems? "  
The paper can be downloaded at  
http://lirhe.univ-tlse1.fr/publications/notes/385-04.pdf  
  
Alain Alcouffe