Mirel™ poly(hydroxy butanoic acid), or PHB copolymers, and their products are known to biodegrade in soil and compost sites and in freshwater and seawater environments. Because they biodegrade in soil, PHB copolymers are very well suited for agricultural mulch film applications. Vegetable-crop growth with PHB copolymer mulch films in various environments has been shown to be considerably better than bare-ground crop growth and similar to crop growth with polyethylene mulch films.

PHB copolymers readily disintegrate through microbial action even at ambient temperatures. The subject mulch films were ploughed into the soil after crop harvest; the buried fragments of mulch film were shown to completely biodegrade. Incineration and landfill disposal are the most commonly used means of disposing of polyethylene mulch films, so natural biodegradation of ploughed-in film is both an eco-friendly alternative and a considerably more efficient farming practice. In addition, Mirel™ PHB copolymers are based largely on renewable resources (corn sugar), unlike petroleum-based polyethylene.