Covering soil in plastic has been a boon for agriculture around the world, especially in China, where an area half the size of California is under polyethylene wrap. Farmers cover their land in razor-thin sheets of the translucent white film to trap moisture and heat and to prevent weeds and pests. The so-called plastic mulch has been shown to boost cotton, maize and wheat yields by a third, while widening the area in which crops can be grown. That has spurred a huge expansion in its use, but one that has come at a cost: Scientists say the practice is causing environmental pollution on an epic scale.
1. Why is plastic mulch a problem?
The plastic isn’t biodegradable and scientists predict it could persist in soil for centuries. It’s a worldwide issue, but one that’s especially acute for China, where about a fifth of arable land contained levels of toxins exceeding national standards, according to 2014 government estimates. Further, the film used in China is less than 0.008 millimeters thick — about half that of sheets used in the U.S., Europe and Japan. That thinness makes the material less robust and more difficult to recover after use. China is predicted to increase its use of plastic mulch by 38 percent to more than 2 million metric tons a year by 2024.