Agricultural fertilization significantly affects nutrients cycling in paddy soils. However, there are few systematic studies on the response of the application of livestock manure and corresponding organic fertilizer resulting in the microorganism and its nutrients entering farmland. Short-term application of pig manure and its corresponding organic fertilizer on the microorganisms of paddy fields were investigated. High-throughput sequencing technology was conducted to comprehensively study the microbial community composition and structure. Our results showed that organic fertilizer effectively enhanced nutrient substances such as nitrogen, phosphorus, and potassium at ripening stage and reduced the pH of soil, benefitting the soil fertility and the growth of rice. Though application of pig manure maintained higher microbial diversity, it increased the relative abundance of several pathogenic bacteria, which could threaten the soil health of the paddy fields. A large number of pathogenic bacteria can be reduced through composting pig manure to organic fertilizer. Nitrifying and denitrifying bacteria such as Anaerolineaceae, Pseudarthrobacter, Bacillus, and Nitrospira in the paddy soil were significantly promoted. The heavy metals such as Pb, Cr, and Cd, and nutrient substances such as phosphorus, as well as temperature, have important influences on the microbial compositions in ripening stage. The correlation analysis revealed more correlation efficiencies were observed with manure application, especially with the application of organic fertilizer. This study will provide a theoretical basis for improving land productivity and sustainable development in paddy fields.

Land formation seriously disturbs coastal salt marsh wetland ecosystems, while its influences on soil organic carbon (SOC) under chronosequences remain unclear. In this study, the impacts of the land formation time (from one to fourteen years) and soil properties on the chronosequences changes of SOC in the nascent wetland of Hengsha Island were investigated. The study results showed the following. (1) As the land-formation time extended, the SOC experienced a significant increase, tripling after a period of 14 years. The changes in SOC occurred mainly in the surface layer but not in the deep soil layer. Specifically, the surface layer’s average SOC reached 5.52 g·kg⁻¹, markedly higher than 3.17 g·kg⁻¹ in the deeper layer. (2) Spearman correlation analysis revealed that the ammonium nitrogen (${\mathrm{N}\mathrm{H}}_4^{+}$-N), aboveground biomass (AGB), and soil water content (SWC) were positively correlated with the SOC. Methane emissions (CH₄) and SOC exhibited a negative correlation. (3) The structural equation model (SEM) illustrated that the duration of soil deformation directly impacted the vegetation growth and affected the distribution characteristics of the SOC by modifying the soil environmental conditions. Changes in SOC following land formation influenced the rapid succession of soil properties and vegetation, with the modification of carbon sinks in the ecosystems.