In a natural ecology, virtually no waste leaves the system; the waste of one species serves as food for other species as materials efficiently cycle and recycle throughout the ecosystem.

By comparison, flows of materials through industrial agricultural systems are much more linear. System inputs (e.g., fertilizers, pesticides and fuel) are synthesized remotely and transported to farms; likewise, most farm outputs travel great distances to points of consumption. The inability of such linear agricultural systems to efficiently process waste in situ, combined with practices that disrupt ecological integrity, result in leakage of materials (e.g., nutrients, pesticide residues and eroded soil) from these systems to become pollutants to off-farm resources.

At least two conditions are required for today's linear-flow agricultural production systems to remain viable: 1) needed inputs must be readily available at costs that do not exceed returns from outputs, and 2) adequate sinks must be available to process wastes that leak from farms. Already, the second condition cannot be met: many streams, rivers, lakes and estuaries currently receive loadings of nutrients and sediments in excess of their capacity to process them. And, it is only a matter of time before inputs manufactured from finite resources (mined fertilizers and fossil fuels) become scarce and prohibitively expensive.

Agricultural systems modeled on principles inherent in ecosystem interactions can reduce reliance on external inputs and minimize or eliminate pollution-causing leakages from farms. This presentation will describe an organic, grass-based dairy farm that processes its milk on farm and markets dairy products locally, as a model of an ecologically based farming system. The interactions of system components that reduce reliance on external inputs, contribute to conservation and enhancement of the resource base, and prevent off-site degradation will be discussed.