Crop rotation British Agricultural Revolution. The rotation between arable and ley is sometimes called ley farming. George Washington Carver (1860s–1943) studied crop-rotation methods in the United States, teaching southern farmers to rotate soil-depleting crops like cotton with soil-enriching crops like peanuts and peas. In the Green Revolution of the mid-20th century the traditional practice of crop rotation gave way in some parts of the world to the practice of supplementing the chemical inputs to the soil through topdressing with fertilizers, adding (for example) ammonium nitrate or urea and restoring soil pH with lime. Such practices aimed to increase yields, to prepare soil
Drinking water supply and sanitation in the United States surface water treatment. Proposed projects: Numerous efforts have been undertaken in the United States to control the pollution of water resources and to make drinking water safe. The most comprehensive federal regulations and standards for the water treatment industry were implemented in the 1970s, in reaction to a huge increase in environmental concerns in the country. In 1972, Congress passed the Clean Water Act (CWA), with the unprecedented goal of eliminating all water pollution by 1985 and authorized expenditures of $24.6 billion in research and construction grants. In 1974, Congress passed the Safe Drinking Water Act, specifying a number of