SUSTAINABLE AGRICULTURAL SYSTEMS - WHAT ARE THE APPROPRIATE MEASURES FOR SOIL STRUCTURE

Sustainable agriculture implies time-scales which are long relative to human lifespan, and the maintenance of productive capacity from the resource base. To evaluate whether agricultural systems are sustainable we need appropriate biophysical and socio-economic measures. Monitoring the status of soils will need some description of their capacity to store and transmit water, nutrients and gases for plants and microorganisms. Most physical and chemical properties of soils which regulate this storage and transmission are time-consuming and complex to measure. Moreover, they are not readily adapted to the requirements of large-scale, long-term environmental monitoring. Robust surrogates are required which can be unambiguously interpreted. A range of such surrogates and their application at different spatial scales is discussed.