cultivar_22_Final_EN

Sustainable Intensification: a new technological model in agriculture 17 scientists but also as citizens asking for new pol- icies. Therefore, in the final section of this article, I will return to this topic of the new public policies required to promote sustainable intensification. The chemical-mechanical technological model The technological model in agriculture includes not only the knowledge base used to create new farm- ing techniques to respond to new challenges but also the way these techniques connect to each other to respond to these challenges (Bonny and Daucé, 1989). In Europe and the most developed countries, and in many developing countries too, the post-war and later period was marked by a new technological model in agri- culture that spread within a framework characterised by the rapid decline in the working agricultural popu- lation, which was absorbed by the expanding industrial and service sectors. Growing manpower shortages and the consequent rise in the corresponding opportunity cost placed higher labour productivity in agriculture at the heart of the new model. Labour productivity in agriculture is the product of two components: the amount of land cultivated per worker and the productivity per hec- tare of cultivated land. To raise labour productivity, therefore, the model proposed a dual replacement of these two components: • Human labour and animal power withmachines and engines to increase the amount of land cul- tivated per worker (the mechanical component of the model); • Biological processes that occur in the agroe- cosystem (e.g. retaining atmospheric nitrogen by soil bacteria or pest control by biotic inter- actions) with industrial chemical inputs (e.g. nitrogen fertilisers or pesticides) to raise yield per hectare of cultivated land (the chemical component of the model). Due to the importance of these two components, it has been called the chemical-mechanical model (Bonny and Daucé, 1989). Both components are based on solid global advances in science and agro- nomics and the use of huge quantities of cheap fos- sil fuel energy to produce the necessary mechanical inputs (machines and fuels) and chemicals (indus- trial fertilisers and pesticides). As a result, agriculture became extremely dependent on this energy sub- sidy. For example, the amount of fossil energy neces- sary to produce 1 kcal of food energy multiplied tenfold in Portugal between 1953 and 1989 from 0.17 to 1.70 kcal (Santos, 1996). Under the chemical-mechan- ical model the new varieties of improved plants are gen- erally very productive. How- ever, this productive poten- tial only manifests itself when these plants are incorporated into heavily modified agro- ecosystems where there is plentiful water and nutrients and an aseptic environ- ment in which pests, diseases and other competing plants are suppressed by the systematic use of pes- ticides. More or less everywhere, a small number of these new highly productive plant varieties created by modern agricultural science replaced multiple varieties adapted to the local agroecosystem that were created over the centuries by the local knowl- edge of generations of farmers. The genetic basis of the chemical-mechanical model narrowed, making the model as a whole increasingly dependent on the availability of cheap energy and therefore vulnerable to its rising price. The spread of the chemical-mechanical model implied a gradual incorporation, at the socioeco- nomic level, of agricultural production systems into the market economy: farm produce markets, mar- kets in new industrial inputs and even credit markets Under the chemical-mechanical model the new varieties of improved plants are generally very productive. However, this productive potential only manifests itself when these plants are incorporated into heavily modified agroecosystems where there is plentiful water and nutrients and an aseptic environment in which pests, diseases and other competing plants are suppressed by the systematic use of pesticides.