Conventional agriculture is a model in which the main component is the technological innovations. Since World War II, agriculture has become an industrialized system characterized by mechanization, monocultures, and the use of synthetic inputs like chemical fertilizers and pesticides (Eicher 2003). The principal emphasis of this system is to maximize productivity and profitability. In part, the success of this system is attributed to the developed highyielding crop varieties of rice and wheat in the late 50s (Figure 5) (Evenson & Gollin 2003). The worldwide trend after 50 years of using the conventional system shows a high increase in the use of these modern varieties (Figure 6). For example, only in the U.S. the trend of food production since the adoption of conventional practices have duplicated the food production in 40 years (Figure 4) (Doering 2003). In the end, the adoption of conventional practices in agriculture have contributed to a large increase in crop productivity, but it is highly debate about the side effects and the true cost of the adoption of these technologies in areas like environmental pollution.

Figure 6. Trend of U.S. agricultural productivity since 1775 to 1980(from Doering 2003)

Figure 5. Modern varieties production by decade and region (from Evenson & Gollin 2003).

Figure 6. Modern varieties diffusion by decade and region (from Evenson & Gollin 2003).

            One of the biggest problems with the conventional model is the loss of agricultural biodiversity. Over the last 60 years, high input of synthetic pesticides and fertilizers plus the monocrops specialization of conventional agriculture have been damaging the diversity of wild flora and fauna species (Scialabba & Hattam 2002). For example, the IUCN (2000) list of threatened species highlights habitat loss as the major threat to biodiversity, with agricultural activities affecting 70% of all threatened bird species and 49% of all plant species. Another problem is that the diversity of agricultural varieties has been decreased drastically. For example, Figure 6 illustrates that in the case of wheat and rice, in the 1990s, more than half of the production comes from only a few modern varieties (Evenson & Gollin 2003). Biodiversity is also affected by high applications of chemicals that are required to maintain these monocrops. In addition, the growing importance of herbicides and pesticides in crop production has changed farming practices considerably. For example, before herbicides, weed populations were kept under control through the use of crop rotation (Morgan & Murdoch 2000). The use of crop rotation is one way to increase biodiversity in the system. However, with the introduction of herbicides, farmers stopped the use of crop rotation. As a result, the replacement of traditional practices like crop rotation by new technologies plus the common use of monocrops have resulted in a dramatic increase in the loss of biodiversity. (see Jeremy's assignment)