The application of razor-thin sheets of polyethylene film across farmland began in the 1950s when agronomists noticed that it could successfully moderate soil temperature, limit weed growth and prevent moisture loss. All essential factors in crop production, this method was found to increase cotton, maize and wheat yields by an average 30%. This was a significant achievement, especially in a world where rising populations rely on increased rates of food production to survive. The promise of increased yields at a relatively low cost formed a multi-billion dollar industry for agricultural plastics. 2,500 square miles of agricultural farmland utilized polyethylene covering for crop care in 2012, requiring 4.4 million tons of plastic. Plastic production for agricultural mulch is expected to see a 69% increase to 7.4 million tons by 2019.