Citation from the book "Grand Transitions: How the Modern World Was Made (English Edition)" written by Vaclav Smil :
"A new and intractable problem has emerged in recent decades with the adoption of crop cultivation under thin (<20 ÎĽm) polyethylene films.
These films are spread in arid and colder regions to create plant microclimate, reduce water losses (cutting demand commonly by 20–30%), prevent weeds and pests, and increase yields. But thin plastic is easily torn, it is not biodegradable, it is not generally recycled, and its shredded bits add up to tens to hundreds of kilograms per hectare in the top 30 cm of soil (60–260 kg/ha). Yields of wheat and cotton are progressively lowered as the residual material in soil accumulates and as plastic bits alter soil structure, damage soil fauna, and interfere with plant germination. Recycling of this plastic is difficult because it is torn and coated with dirt; obviously, thicker films would last longer and would be easier to retrieve. Polyethylene contamination is now common in scores of countries, but China has the largest area of such plastic-covered fields: by 2011 about 1.2 Mt of polyethylene were used to cover nearly 20 million ha, or about 15% of the country's cultivated area (Yan et al. 2014). Plastic films also release phthalates (common plasticizers) whose levels in Chinese soils are now usually at the high end of the global range, and are mostly higher than allowable concentrations (LĂĽ et al. 2018; Li et al. 2016). In China about 20% of arable land is already contaminated with different kinds of toxins whose concentrations exceed national standards. Ground cover is not the only use of polyethylene films in cropping. Thicker films are also used to create plastic greenhouses for hydroponic cultivation of vegetables. The world's highest concentration of these temporary shelters, visible on satellite images, is in Spain's AlmerĂa province (Figure 3.5): with the exception of roads and a few small settlements the southernmost tip of AlmerĂa is under 450 km2 of plastic to produce a major share of the European Union's winter vegetables by using cheap migrant labor (NEPIM 2019). Besides the obviously large mass of torn plastic waste and enormous water demand in an arid region this extensive plastic cover also increases the region's albedo."
