Resource use efficiency and renewability. Assessment of low-input agricultural production using eMergy.

Until now the demand for food has been met by the use of abundant and cheap fossil fuels; however weneed to reconsider our modes of production to avoid a global environmental crisis. Food productionsystems should, therefore, increasingly rely on renewable inputs and increase their stability by reducing dependency on external input. We apply the emergy approach to evaluate resource use efficiency of twolow-input innovative farms while distinguishing between use of renewable and non-renewable resources aswell as local and global origin of resources. This study is a part of the SOLIBAM (www.solibam.eu) projectfunded by the European commission under the Seventh Framework Programme.We apply an approach where we include efficiency in resource use to produce food energy joules soldwhile distinguishing between use of renewable and non-renewable resources as well as on-site, local andnon-local resources. Result shows that the large farm (75 ha) had an input of renewable resources of 32%while the small (6 ha) had a renewable fraction of 26%. The latter is based on assuming that the firewoodused is 50% renewable. If this percentage is increased to 100% then both farms have a renewable fractionof resource use of about 39%. In conclusion, especially fuels and machinery may be subject to management improvements as theserepresent a large fraction of the total eMergy use. Further, they are characterized by being mainly nonrenewable.The larger resource inputs per food Joule to the small farm compared to the larger farm may bean economy-of-scale consequence. The larger farm can grow more crops on-site reducing the externalinputs. Also the larger farm area may reduce the input of machinery per ha of cultivated area, reducing thispart of the total use per food Joule produced.