Plastic mulch film residues in agriculture: impact on soil suppressiveness, plant growth, and microbial communities

Plastic mulch film residues have been accumulating in agricultural soils
for decades, but so far, little is known about its consequences on soil
microbial communities and functions. Here, we tested the effects of
plastic residues of low-density polyethylene and biodegradable mulch films
on soil suppressiveness and microbial community composition. We
investigated how plastic residues in a Fusarium culmorum suppressive soil
affect the level of disease suppressiveness, plant biomass, nutrient
status, and microbial communities in rhizosphere using a controlled pot
experiment. The addition of 1% plastic residues to the suppressive soil
did not affect the level of suppression and the disease symptoms index.
However, we did find that plant biomasses decreased, and that plant
nutrient status changed in the presence of plastic residues. No
significant changes in bacterial and fungal rhizosphere communities were
observed. Nonetheless, bacterial and fungal communities closely attached
to the plastisphere were very different from the rhizosphere communities
with overrepresentation of potential plant pathogens. The plastisphere
revealed a high abundance of specific bacterial phyla (Actinobacteria,
Bacteroidetes, and Proteobacteria) and fungal genera (Rhizoctonia and
Arthrobotrys). Our work revealed new insights and raises emerging
questions for further studies on the impact of microplastics on the
agroecosystems.