Methane emissions and rice yield in a paddy soil: the effect of biochar and polystyrene microplastics interaction

Biochar has been suggested as a soil supplement to improve soil fertility and mitigate methane (CH4) emissions from rice farming. On the other side, the world is covered in microplastics (MPs), which are tiny pieces of degraded plastic. Studies have paid little attention to the combined biochar and soil contamination caused by MPs, particularly the mechanism of their interactions with CH4 emissions. In this study, a pot greenhouse experiment with a randomized complete block design (RCBD) was carried out to examine the impact of polystyrene (PS), sugarcane bagasse biochar (SBB), and their interaction (PS*SBB) on the CH4 emission and rice yield in a rice-cultivated paddy calcareous soil. The largest CH4 emission occurred at 30 and 70 days following rice planting, which corresponds to the tillering and heading stages of rice growth. Adding SBB to our paddy soil samples reduced CH4 emissions. Our findings showed that applying PS at different rates greatly increased CH4 emissions in our soil samples under ambient conditions. Our results showed that adding SBB can partially offset the negative effects of PS in the soil. In comparison with when PS was applied alone, the co-application of SBB and PS reduced PS’s stimulation of the global warming potential (GWP) by altering its impacts on the structure and function of the soil’s microbial community and the carbon and nitrogen contents of the microbial biomass. We come to the conclusion that interactions between PS and the use of SBB have an impact on GWP, microbial community activities, and CH4 emissions. Both SBB rates resulted in a considerable increase in height, biomass, and rice grain as compared to control. Our findings indicated that PS negatively impacts rice height, grain yield, and biomass and that the addition of SBB can partially counteract PS’s negative effects on the rice. Further study is needed to understand how various types of MPs interact with soil amendments to affect ecosystem function.