Plastic Film Covering 12% Of China’s Farmland Pollutes Soil.
Plastic-film mulch is widely used to increase the productivity of crops, vegetables and fruit trees in cold and arid or semiarid regions of China. Use increased from 6000 t, covering 0.12 million ha, in 1982, to 1.2 million t, covering almost 20 million ha, in 2011. The thin (4-8 µm) polyethylene film used in China is slow to degrade, easily damaged, difficult to reuse for a second season and difficult to remove. Residual plastic in the top 0.3 m soil layer is now estimated to vary from 72 to 260 kg/ha, depending on number of years use, percentage of ground covered and film thickness. Research results showed that plant growth was affected when residual plastic exceeded 37.5 kg/ha in the soil; the emergence of winter wheat seedlings decreased by 25% and the tiller number decreased by 17%. Cotton yields were reduced by 4%, 8%, 12% and 19%, respectively when the amount of residual plastic in the soil was 80, 170, 280 and 370 kg/ha. Use of photo- and bio-degradable plastics is currently considered to be too expensive for agricultural use in China, but we suggest that use of thicker (15 µm) and stronger film that can be reused for two or more years, together with planters that can collect the residual plastic while (planting) sowing, should be developed. Credit: World Agriculture.
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