# Biodegradable microplastics can cause more serious loss of soil organic carbon by priming effect than conventional microplastics in farmland shelterbelts ## Description of the data and file structure ### dataset Raw data.csv Soil data for the variables tested in the paper. Variables are as follows: * Group = The number of the microplastics addition and control group * First emission of soil CO2 (mg g-1 SOC) = CO2 release rate of soil organic carbon at first sampling * δ13 C of CO2 in first samping(‰) = The δ13 C of CO2 at first sampling * DOC(mg kg-1) = Dissolved organic carbon content of soil samples after incubation * MBC(mg kg-1) = Microbial biomass carbon content of soil samples after incubation * DTN(mg kg-1) = Dissolved total nitrogen content of soil samples after incubation * MBN(mg kg-1) = Microbial biomass nitrogen content in soil samples after incubation * NH4+-N(mg kg-1) = Content of ammonium nitrogen in soil samples after incubation * NO3--N(mg kg-1) = Nitrate nitrogen content in soil samples after incubation * pH = pH value of soil sample after incubation * null = No data were obtained. In this study, conventional microplastics exhibited no degradation during the short-term incubation; therefore, 13C isotopes were not employed to differentiate soil CO2 emissions in the treatment group involving conventional microplastics. One-way analysis of variance (ANOVA) examined the differences in soil-derived CO2 emission, SOC loss, hydroxyl index (HI), soil physiochemical properties and microbial characteristics of different soils and MPs groups (P < 0.05). The above experimental data were conducted using SPSS 27.0. Structural equation model was analyzed using Amos 26.0 software to explore the pathways of MPs addition on cumulative soil-derived CO2 emissions.

Globally, the widespread utilization of plastic products has resulted in the accumulation of microplastics (MPs) in the soil. MPs have the potential to impact the loss of soil organic carbon (SOC). Nevertheless, the influence of different types of MPs on SOC loss remains uncertain. In this study, a 38 d’ incubation experiment with two kinds of conventional MPs (polyethylene (PE), polypropylene (PP)) as well as two kinds of biodegradable MPs (polyhydroxyalkanoate (PHA), polylactic acid (PLA)) were added into three types of soil (loam, sandy loam, and sandy soil) in farmland shelterbelts, and the sources of CO2 emissions was distinguished by the difference in 13C isotope abundance between the biodegradable MPs (PHA and PLA) (-10.02 ~ -9.92 ‰) and the soil (-24.39 ~ -22.86 ‰) (>10‰). In conjunction with the structural characterization of MPs, as well as soil physicochemical properties and microbial characteristics, we observed that the conventional MPs did not degrade in short term incubation, but significantly enhance soil-derived CO2 emissions by altering the dissolved N content (NH4+-N and DTN) and reducing microbial biomass carbon (MBC) content only in sandy loam soil (P<0.05). Biodegradable MPs degraded significantly, and enhanced soil-derived CO2 emissions by reducing soil dissolved total N (DTN) and NO3--N contents in loam, sandy loam and sandy soil (P<0.05). Overall, the input of biodegradable MPs causes a more serious loss of SOC than conventional MPs as the soil sand content increased in short term incubation, which needs to be considered in predicting the global impact of increasing biodegradable MPs pollution.