Entropy as an indicator of sustainability in agro-ecosystems: North Germany case study

An indicator for the sustainability of agro-ecosystems, based on the overproduction of entropy, is suggested. In the main research area of the Kiel Ecology Centre energetic input and output parameters characterising agriculture were assessed in 1988 and 1897. It is demonstrated how excess of entropy changes with land management. Different kinds of crops have different values for their overproduction of entropy. It is assumed that these differences are due to a varying, but in many cases an excessive, use of (organic) fertilisers. The characteristics of the crop itself play a minor role. Although the method allows only rough estimations of entropy in agro-ecosystems, it can be stated that, due to a reduction of artificial energy input, sustainability was improved, comparing with the 1988 and 1997 results. Nevertheless, all the examined crop fields are far from reaching a sustainable state from a thermodynamic point of view.