Soil Quality

I have read the exchange pertaining to John Ikerd's paper with 
interest.  Aside from the more philosophical points that are being 
expressed and postulated, there appears to be some need of term 
clarification arising from the discussion.  Granted this is not a 
formal medium; however, we should have some agreed-upon terms since
we cannot see one another and conversation via this medium is very 

The term is "productivity".   In terms of natural systems it has a 
specific meaning in the ecological sense and in the economic 
sense as well.  Ecologically, productivity is the rate at which 
radiant energy is stored by photosynthetic and chemosynthetic of 
producer organisms.  It is the rate of accumulation of biomass (i.e.
production).  Management applied to natural systems is said to be 
good or bad based on productivity of management systems or their 
components.  Productivity in this sense has to do with the 
efficiency of use of inputs to produce outputs.  One can increase
productivity in this sense by increasing outputs without 
increasing inputs or by maintaining outputs while decreasing 

Because sustainable agriculture relates to both the physical and
the economic system we should be clear when we are referring to 
terms such as productivity.  Especially when we may be referring
to the harvested production and not necessarily the rate of 
accumulation of production.  

Application of nitrogen inputs may increase production and 
economic productivity; however, by use of alternative sources of 
nitrogen and other management inputs, productivity may or may 
not be improved.

Marc Safley