Environmental Engineering Reference
In-Depth Information
and crop rotations (to let the soil recover nutrients) to ensure a plentiful supply of food.
The injection of additional energy into agricultural systems began with animal power and
manure, later involving fossil fuels with the use of tractors, mechanized irrigation (canals
and water pumps), and artificial fertilizers. Between 1940 and 1990, the global use of
chemical fertilizers grew from 4 million to 150 million tonnes per year. Like so many other
innovations, fertilizers have been a mixed blessing. They have greatly boosted crop yields,
providing food for an estimated 2 billion people, but have also encouraged monoculture,
reduced biodiversity, contaminated watercourses and significantly impaired the quality of
the soil.
