The effects of microplastics on crop variation depend on polymer types and their interactions with soil nutrient availability and weed competition

Microplastics pollution of agricultural soil is a global environmental
concern because of its potential risk to food security and human
health. Although many studies have tested the direct effects of
microplastics on growth of Eruca sativa Mill., little is
known about whether these effects are regulated by fertilization
and weed competition in field management practices. Here, we
performed a greenhouse experiment growing E. sativa as target species in
a three-factorial design with two levels of fertilization (low
versus. high), two levels of weed competition treatments (weed
competition versus no weed competition) and five levels of
microplastic treatments (no microplastics, Polybutylene
adipateco-terephthalate [PBAT], Polybutylene succinate [PBS],
Polycaprolactone [PCL] or Polypropylene [PP]). Compared to the
soil without microplastics, PBS and PCL reduced aboveground biomass and
leaf number of the E. sativa. PBS also resulted in increased root
allocation and thicker roots in E. sativa. In addition,
fertilization significantly mitigated the negative effects of PBS and PCL
on aboveground biomass of E. sativa, but weed competition significantly
promoted these effects. Although fertilization alleviated the
negative effect of PBS on aboveground biomass, such alleviation
became weaker under weed competition than when E. sativa grew
alone. The results indicate that the effects of specific polymer types on
E. sativa growth could be regulated by fertilization, weed
management, and even their interactions. Therefore, reasonable
on-farm management practices may help in mitigating the negative
effects of microplastics pollution on E. sativa growth in
agricultural fields.