Problems with Plastics

摘要

Plastics and plasticulture are widely utilized and increasing in modern-day horticulture throughout the world. Around the world, millions of tonnes of plastic are used each year to mulch crops, cover greenhouses, and to construct a variety of plant containers and plug flats. Plastics are light weight and versatile and have thus found a multitude of uses in crop production and landscaping. However, the fate of plastic in our environment is a serious issue that needs to be resolved. Unfortunately, our"green" industry is not so green when it comes to reusing and recycling the vast quantity of plastic generated (Fig. 1). Landfills do not seem an appropriate option, and, unless stringently controlled, burning can release a number of potentially dangerous compounds into the atmosphere. Containers can be reused, but there are issues related to disease and lack of standard sizes. Greenhouse coverings and mulch films cannot be reused, since they deteriorate under UV radiation. Another complicating factor is that several different types of plastic are used in the horticultural industry, including low density polyethylene, high-density polyethylene, polypropylene, and high-impact polystyrene. To maintain the highest quality of the recycled product, these need to be carefully sorted and handled separately. Even if properly sorted, various contaminants including soil and organic matter reduce the quality of recycled plastic compared to virgin material. Every time plastic goes through the recycling process, contaminants and structural degradation reduce the quality of the plastic, such that it is difficult or impossible to manufacture the same product again and again. The list of problems goes on and, to date, more plastic is burned or put in landfills thanis recycled or reused.