DOI: 10.5061/dryad.t76hdr8dx
title: Data from: Microplastic biodegradability does not modify plant carbon input in soil but accelerate soil carbon loss in agroecosystems

description: Microplastics (MPs) are emerging contaminants that disrupt terrestrial
 carbon (C) cycling, yet how their biodegradability modulates the turnover
 of plant-derived C remains unclear. Here, we investigated how two widely
 used MPs—non-biodegradable polyethylene (PE) and biodegradable polylactic
 acid (PLA)—affected the fate of photosynthetically fixed C in dryland
 agroecosystem. The goal was to explore how MPs influenced C fluxes across
 soil-plant-atmosphere continuum (SPAC) and assess their implications on
 climate change. We conducted a two-year field experiment to evaluate how
 PE and PLA-based MPs affected plant photosynthetic C fixation and its
 subsequent turnover in soil. Using 13CO2 pulse-labeling, we traced the
 flow of photosynthetically fixed C across the SPAC under low, medium and
 high MPs concentrations. We quantified: (i) 13C distribution in plant
 shoots, roots, and bulk soil; (ii) 13C allocation among soil aggregate
 size fractions; and (iii) microbial EEAs, CAZy gene abundance, and soil
 respiration dynamics. Soil C sink capacity tended to decline for both MPs
 types, as cumulative soil CO2 emissions increased. On average, 13C
 retained in soil decreased from 50.8 to 41.1 mg m-2 in MPs treatments,
 relative to the control. Interestingly, the underlying mechanisms differed
 from MP types. Non-biodegradable PE-MPs weakened soil aggregation and
 reduced 13C retention in macro-aggregates. However, biodegradable PLA-MPs
 generated marginal effects on aggregation, and enhanced the activity of
 microbial hydrolase, which negatively affected C retention. Moreover,
 metagenomics confirmed that PLA-MPs enhanced microbial decomposition
 capacity by enriching C degradation and energy metabolism genes. Finally,
 photosynthetic C assimilation remained unchanged with increasing MPs
 concentrations, regardless of MPs types. Synthesis and applications. Both
 MP types can evidently impair soil C pools and differentially alter soil C
 cycling via the biodegradation-dependent mechanisms. These findings
 challenge the widely held assumption that biodegradable MPs are inherently
 environmentally benign, as their presence in soils undermines C storage
 capacity. The findings offer insights into future applications as: 1) to
 phase down the increment and stock of soil MPs, in favour of truly green
 alternatives of plastic mulching; 2) to update the estimation methods of
 soil C emission in global terrestrial ecosystems considering the presence
 of soil MPs.
description: # Data from: Microplastic biodegradability does not modify plant carbon
 input in soil but accelerate soil carbon loss in agroecosystems Dataset
 DOI: [10.5061/dryad.t76hdr8dx](https://doi.org/10.5061/dryad.t76hdr8dx) ##
 Description of the data and file structure #### Files and variables File:
 DATA.csv All raw data associated with the figures have been compiled in
 the file DATA.csv. *Notes: Treatment: CT: control, no addition of
 microplastic PE-L: polyethylene microplastics in low concentration PE-M:
 polyethylene microplastics in medium concentration PE-H: polylactic acid
 microplastics in high concentration PLA-L: polylactic acid microplastics
 in low concentration PE-M: polylactic acid microplastics in medium
 concentration PE-H: polylactic acid microplastics in high concentration
 Data： *13C-Shoot/Root/Soil/Respiration: 13C content in shoots, roots, soil
 and soil respiration (mg m^-2^) *Total recovery: Total recovery of 13C (%)
 *Shoots(%)/Roots(%)/Soil(%)/Respiration(%): The recovery distribution of
 13C in shoots, roots, soil, and respiration (%). *MacroC: 13C in
 macro-aggregates (mg m^-2^) *MicroC: 13C in micro-aggregates (mg m^-2^)
 *MicroC: 13C in silt and clay (mg m^-2^) *Macrog/Microg/Siltg: Weight
 distribution of soil aggregates (g) *MWD: mean weight diameter (mm) *MBC:
 microbial biomass carbon (mg kg^-1^ soil) *MBN: microbial biomass nitrogen
 (mg kg^-1^ soil) *Soil enzyme activity: C-hydrolase; N-hydrolase;
 C-oxidase (n mol h^-1^ g^-1^) ##