Tracking biodegradable microplastics: Mobility in agricultural soils under different environmental conditions

Area of Science:

• Environmental Science
• Soil Science
• Polymer Science

Background:

• Conventional agricultural plastics pose environmental risks.
• Biodegradable mulching films are an alternative, but their microplastic (MP) generation is a concern.
• Understanding MP fate in soil is crucial for sustainable agriculture.

Purpose of the Study:

• To investigate the mobility and fate of polybutylene adipate terephthalate (PBAT) microplastics from biodegradable films.
• To compare MP behavior in bare versus cultivated soil under various water-input scenarios.
• To quantify MP losses through surface runoff and infiltration.

Main Methods:

• Experimental units with PBAT-amended soil (0.5 wt%) were established.
• Barley cultivation was implemented in half of the units.
• Runoff and infiltration were monitored over 5 months, with soil analysis post-harvest.

Main Results:

• Most MPs remained in the topsoil (0-10 cm).
• Cultivation significantly enhanced MP retention (70% in 0-5 cm vs. 50% in bare soil).
• Runoff MP mobilization was minimal (1.6% in bare soil, 0.02% in cultivated soil); infiltration was negligible (<0.001%).

Conclusions:

• Vegetation cover, through cultivation, reduces MP runoff losses and promotes retention in upper soil layers.
• High-intensity rainfall events drive MP runoff in bare soils.
• Water infiltration volume influences MP movement to deeper soil horizons, indicating complex fate dynamics.