Microplastics (MPs) contamination presents a significant global environmental challenge, with its potential to influence soil carbon (C) dynamics being a crucial aspect for understanding soil C changes and global C cycling. This meta-analysis synthesizes data from 110 peer-reviewed publications to elucidate the directional, magnitude, and driving effects of MPs exposure on soil C dynamics globally. We evaluated the impacts of MPs characteristics (including type, biodegradability, size, and concentration), soil properties (initial pH and soil organic C [SOC]), and experimental conditions (such as duration and plant presence) on various soil C components. Key findings included the significant promotion of SOC, dissolved organic C, microbial biomass C, and root biomass following MPs addition to soils, while the net photosynthetic rate was reduced. No significant effects were observed on soil respiration and shoot biomass. The study highlights that the MPs concentration, along with other MPs properties and soil attributes, critically influences soil C responses. Our results demonstrate that both the nature of MPs and the soil environment interact to shape the effects on soil C cycling, providing comprehensive insights and guiding strategies for mitigating the environmental impact of MPs.

To better understand the responses of vegetable yields in a greenhouse system to organic fertilizer through a quantitative evaluation based on peer-reviewed journal articles and in consideration of environmental managerial factors. We conducted a meta-analysis of 453 paired observations from 68 peer-reviewed journal articles to assess the response of vegetable yields in greenhouse vegetable systems in China to organic fertilization. Compared with the control (no organic fertilizer), organic fertilization significantly increased the yields of vegetables by 44.11% on average. The response of vegetable yields to organic fertilizer tended to increase with the increasing experimental duration. Organic fertilizer application had the greatest potential for leafy vegetables (+76.44%), in loamy soils (+53.94%), at moderate organic fertilizer carbon input levels (+54.13%), and in soils with moderate initial soil total nitrogen levels (+50.89%). Aggregated boosted tree analysis indicated that organic fertilizer carbon inputs, vegetable type and experimental duration were the predominant factors that manipulated the response of vegetable yields to organic fertilizer application. The rational application of farmyard manure would be a promising strategy for increasing vegetable yields in greenhouse vegetable systems in China. Factoring in vegetable type, carbon and nitrogen inputs of organic fertilizer, and soil texture would benefit vegetable yields with the application of organic fertilizer.