Today’s agriculture has to face the new challenge that derives from a new evolutionary era of civilisation that has been called “Anthropocene”. Human dominion on Earth with exploitation of natural resources and environmental pollution is not socially acceptable anymore, since it leads to self-destruction in a confined “spaceship” like the planet Earth. A different cultural attitude to guide human behaviour is required in order to set up the base of a sustainable development for man and the whole biosphere. Agriculture scientists can play a role in providing a step towards agriculture sustainability. However, agriculture scientists need to be able to educate both themselves and the civic society with a new systems paradigm that focuses more on relations than on single components of agriculture reality, as a disciplinary approach usually does. Transdisciplinarity in agriculture theory and practice is required in order to face the new challenge of sustainability. Agroecology is a transdisciplinary area of enquiry that has both a scientific and a philosophical base for promoting sustainability in agriculture.
Here I review the most important areas of interface that qualify agroecology methodology and contents. Agroecological achievements are presented according to their chronology in order to account for the developmental process that agroecology has undergone. Concerning methodological achievements, four pillars of agroecological epistemology have been identified: (1) the agroecosystem concept; (2) the agroecosystem hierarchy; (3) the farm system as a decision making unity; and (4) the representation of agriculture as a human activity system. These four epistemological tools are models of agricultural organisation that allow us to understand, project and manage it as a process. They constitute the theoretical base of agroecology derived from the systems approach, which is at the core of ecology. With the aid of these four tools of enquiry, an agroecosystem monitoring process worldwide started since the early 1970s and it is still running. Information on the processes of energy transfer (energetics), productivity, nutrient cycling and biodiversity dynamics at different levels of agroecosystem hierarchy is growing. This constitutes the first knowledge body package of agroecology, a science that links structure and functioning of agroecosystems. This data collection has allowed scholars to raise judgements about the resource use efficiency, the environmental impact and the sustainability of agroecosystems at different hierarchical level of organisation. Since the 1990s, agroecology research and applications have focused more and more on the issue of sustainability. Attention to the problem of agriculture sustainability has promoted a spontaneous dialogue between scholars of ecology, agronomy, economics and sociology. Matching ecology with agronomy has produced more awareness on the benefits of increasing biodiversity at field, farm and landscape levels. Increasing within-field biodiversity with policultural patterns, such as crop rotations, cover cropping and intercropping, and increasing between-field biodiversity with field-margin management, hedgerow maintenance or introduction, and agroforestry applications, are practical solutions to the problem of enhancing biophysical sustainability of agroecosystems. Recent research on the role of field size for evaluating the trade-off between machinery efficiency and loss of biodiversity-friendly habitats in arable landscapes shows that there is no need for bigger field size beyond an evaluated threshold of 1–2 ha above which machinery efficiency increases very little (Rodriguez and Wiegand 2009). Matching ecology with economics and sociology has instead revealed that contrasting paradigms are still at work. One of the most outstanding example of paradoxical contrast between economic and ecological outcomes is the CAFO (Confined Animal Feeding Operations) system for meat production. The CAFO system is economically regarded as the most advanced intensive feedlot system for livestock production, although it contributes large greenhouse gas emissions. If the use of CAFOs is expanded, meat production in the future will still be a large producer of greenhouse gases, accounting for up to 6.3% of current greenhouse gas emissions in 2030 (Fiala 2008). An ecological conversion of economics is demanded whether the end of sustainability has to be pursued. Organic farming worldwide is the most important example of agriculture regulated by law with the expressed end of integrating bio-physical and socio-economic requirements of sustainability. The latest report by IFOAM (International Federation of Organic Agriculture Movements) (2007) mentions increasing annual rates for organic farming and shows that 32.2 millions of hectare were certified as “organically grown” in 2007 with more than 1.2 millions of farmers involved in the world. The global debate about agriculture sustainability has enormously enlarged the cultural landscape for mutual criticism between different disciplinary, traditionally separate areas. The area of agroecology enquiry is now really operating as “glue” at a transdisciplinary level, bridging the gap between different disciplines and between theory and practice of agriculture. Measuring agriculture sustainability through indicators of both biophysical and socio-economic performances is now a common praxis of international, national and local institutions. New curricula in Agroecology at academic level are performed in order to give an institutional base for education towards agriculture sustainability. A final outlook section provides some examples of agroecological approaches and applications for making a crowed planet more sustainable.
Agroecology Systems paradigm Transdisciplinarity Integration Sustainable agriculture