Agriculture as a system.

No eco-system or agro-system can be perfectly closed. But the degree to which the system can maximise how it retains energy and materials within cycling processes is a measure of their efficiency, resilience and persistence. (For a theoretical explanation of this see: Ripl & Wolter, 2002)

LINK

http://www.tu-berlin.de/~Limnologie/download/ripl_wolter_2002_ecosystem_function_and_degradation.pdf

Cycling processes are those which retain energy and materials such as water and nutrients within the system, and re-use them. The alternative is loss or leakage from the system. Irreversible losses are a measure of system degradation.

We can take solar energy and water as examples. Both are used by the eco- or agro- system in growing plants. Systems which capture and retain more energy and water can grow more plants (or plant biomass). Loss of energy or water from the system is a lost opportunity for more plant growth. Plant growth is a key to energy capture, nutrient cycling and water cycling. This is discussed more fully in relation to grazing management in Better Grazing

(LINK within webpage).

Only systems that maximise the proportion of matter and energy cycled in relation to that lost irreversibly can be considered “sustainable”. While this may sound very theoretical, the application of any practical management activities and systems can only ever be “sustainable” if they are consistent with the theory.