Data from: Impact of agricultural weathering on physicochemical properties of biodegradable plastic mulch films: comparison of two diverse climates over four successive years

Biodegradable plastic mulch films (BDMs) are essential in the production
of vegetable and specialty crops due to their promotion of increased crop
yield and quality. Unlike conventional polyethylene (PE) mulches, BDMs can
be tilled into the soil after crop harvest to undergo biodegradation,
thereby leading to minimal environmental impact. Agricultural weathering
impacts both the performance of BDMs during crop production as a barrier
to weeds and biodegradability of BDMs in the soil. To better understand
the relative importance of climatic factors, the change of physicochemical
properties of BDMs during single-season, 3-4 month, field trials for
vegetable production at two diverse climates (Knoxville, TN and Mount
Vernon, WA) across four successive years (2015-2018) was evaluated. Mulch
treatments consisted of four commercially available BDMs composed
primarily of polybutylene co-adipate- co-terephthalate (PBAT) that
differed in color and polymeric feedstock, a black experimental BDM
prepared from polylactic acid/polyhydroxybutyrate (PLA/PHA) blend, and
conventional PE mulch. Mulch deterioration did not vary extensively
between years. Solar radiation, an important factor to degradation of
mulches, was higher in WA than TN in most sampling years. Yet, degradation
occurred more greatly for BDMs in TN, which is attributable to higher
temperatures in TN. Loss of mechanical properties and color was greater
than chemical property changes. Differences in the extent of molecular
weight decrease between years correlated significantly with solar
radiation exposure at the two locations. A black-colored PBAT-based BDM
was less susceptible to degradation than equivalent clear and
white-on-black films, due to carbon black acting as a photostabilizer. The
impact of weathering also differed between three commercially available
PBAT-based films. The PLA/PHA mulch was more susceptible to degradation
than PBAT-based BDMs, particularly in the warmer location, TN, partially
due to a leaching out of PHA and lower-molecular weight polymer molecules.
The extent of change for physicochemical properties of BDMs due to
agricultural weathering is greatly affected by polymeric composition, and
is greater in warmer climates.