Sustainable agricultural productivity over the long term was not a major issue in the 1960s and 1970s, as food resources did not appear to be threatened1. The attention was on producing enough food to overcome the immediate problems of food deficit. But the environmental effects of intensive agriculture, such as soil erosion and Stalinization, pollution of groundwater and surface water, and loss of biodiversity, have led to the concerns of sustainability of agricultural production and it became a burning issue, on both the global and national scale.