Mulching film in agriculture is the practice of covering the soil around plants to improve the growing conditions for the crop through control of weeds and insects, increase soil temperature, moisture retention, reduction of evaporation, prevention of soil erosion, less crop contamination, and improve germination rates. Historically natural mulches such as straw, compost, hay and wood chippings have been used but since 1950s paper and plastics mulching have been tried. Because of its poor wet strength and high price, paper has been found less effective and more costly than plastic, thus plastic mulch film is the primary choice. Most of plastic mulch films such polypropylene (PP), low-density polyethylene (LDPE), high-density polyethylene (HDPE), and poly(vinyl chloride) (PVC) are not biodegradable and are typically removed after each growing season. Recovery of these plastics from the soil is difficult and can affect successive crop yields while causing substantive cost to the environment and farmers. Due to increasingly stringent regulations regarding use of non-degradable plastic in agriculture they are likely to be phased out soon. In the past decades several classes of ‘biodegradable’ materials have been studied but most of these films are reported to be relatively weak in mechanical properties, not efficiently degradable and cost prohibitive compared to conventional plastic mulches. For instance, the standards for degradation in compost (ISO 17088, ASTM D6400) specify that at least 90% of the organic carbon need to be converted to CO2, leaving room for up to 10% of the organic carbon to remain. Because of changes to more stringent regulations, researchers worldwide are now putting extra effort into research on biodegradable polymers from renewable resources. Consequently, biodegradable plastic mulch (BPM) is now being considered as a potential and viable option for the agriculture application in the near future.
