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

An indicator for the sustainability of agro-ecosystems, based on the overpr oduction of entropy, is suggested. In the main research area of the Kiel Ec ology Centre energetic input and output parameters characterising agricultu re were assessed in 1988 and 1897. It is demonstrated how excess of entropy changes with land management. Different kinds of crops have different valu es for their overproduction of entropy. It is assumed that these difference s are due to a varying, but in many cases an excessive, use of(organic) fer tilisers. The characteristics of the crop itself play a minor role. Althoug h the method allows only rough estimations of entropy In agro-ecosystems, i t can be stated that, due to a reduction of artificial energy input, sustai nability was improved, comparing with the 1988 and 1997 results. Neverthele ss, all the examined crop fields are far from reaching a sustainable state from a thermodynamic point of view. (C) 2000 Elsevier Science B.V. All righ ts reserved.