Analysis of the time course of degradation for fully biobased nonwoven agricultural mulches in compost-enriched soil

Sathiskumar Dharmalingam, Douglas G Hayes, Larry C Wadsworth, Rachel N Dunlap
  • Textile Research Journal, November 2015, SAGE Publishing
  • DOI: 10.1177/0040517515612358

Physicochemical changes of plastic mulches during biodegradation

What is it about?

The study focused upon the changes in different physicochemical properties of plastic mulches prepared from biopolymers: polylactic acid (PLA) and a blend of PLA and polyhydroxyaltanoate during biodegradation of the plastics in soil. Plastic mulches are an inherent component of the production of many fruits and vegetables, to prevent weeds and reduce evaporative loss of water. This investigation provided a deeper insight into the underlying events and stages of biodegradation, and guidance as to which properties should be monitored during the time course of biodegradation.

Why is it important?

Our study showed that there are several stages to biodegradation of plastics in soil. During the first stage, soil micoroorganisms "open up" the structure of the plastic, to allow its use as a carbon source, observable through a major loss pf tensile strength. Second, microorganisms selectively utilize preferable components of the plastics as carbon sources, such as polyhydroxyalkanoates (PHA; from a PHA/polylactic acid blend), and regions of lower crystallinity. Subsequently, the biopolymeric components underwent a slow and steady degradation, i.e., a slow and linear decrease of molecular weight with time.

Perspectives

Dr Douglas Gordon Hayes (Author)
University of Tennessee Knoxville

This study provides a linkage between physicochemical changes of biodegradable plastics and the process of biodegradation under ambient soil conditions. Yet, I believe the paper shows that further research is needed to understand the microbiological events that occur simultaneously, such as changes of microbial community composition and metabolic changes. My hope is that this research will further enhance research and development related to biodegradable plastic mulches for sustainable production of fruits and vegetables.

The following have contributed to this page: Dr Douglas Gordon Hayes