Plastic greenhouses, Almeria, Spain. Polytunnels and plastic greenhouses cover approximately 20,000 hectares of land (more than 75 square miles) in Almeria. This view shows roughly six square miles. The use of plastic covering – known as plasticulture – is designed to increase produce yield, increase produce size, and shorten growth time (Daily Overview/Satellite images (c) 2015, Digital Globe, Inc)