"The appellation of the word 
      'sustainable' to a farming system 
     remains a matter of opinion. Most 
              farmers and agricultural 
         professionals have a 'feel' for 
             what 'sustainable' is…." 
     (Smith, M., 1994. The Real Dirt: Farmers Tell About Organic 
         and Low-Input Practices in the Northeast, Northeast 
                    Organic Farmers Association.) 
                                   
            To paraphrase Rodale: 
       Sustainability is like being 
      pregnant—either you are or 
                  you aren’t. 
                           
    Goal: To develop a readily-measurable 
    indicator of farm (agroecosystem) 
    sustainability. The difficulty of measurement 
    should be comparable to organic certification. 
    Such an indicator would enable:
    • Policy makers to support sustainable 
      farm operations through legislation.
    • Consumers to support sustainable farm 
      operations through purchases.
    • Farmers to analyze and address the 
      sustainability of their own operations.
                             
                     First we need a definition:
         "A sustainable agriculture is one that, over the 
       long-term, enhances environmental quality and the 
          resource base on which agriculture depends; 
       provides for basic human food and fiber needs; is 
      economically viable and enhances the quality of life 
        for farmers and society as a whole" (FAO, 1989).
           Nice, but difficult to operationalize.
                                  
           Characterizations of 
      agricultural sustainability 
      Taken from: Hansen, J.W., 1996. Is Agricultural Sustainability a Useful 
               Concept? Agricultural Systems, 50:117-143.
       Four frameworks for defining 
       sustainability. 
       Each framework leads naturally to 
       methods of measurement.