Microorganisms play a crucial role in regulating the turnover and transformation of soil organic carbon (SOC), whereas microbial contribution to SOC formation and storage is still unclear in coastal wetlands. In this study, we collected topsoil (0–20 cm) with 7 salinity concentrations and explored the shifts in microbial residues [represented by amino sugar (AS)] and their contribution to the SOC pool of coastal wetlands in the Yellow River delta. The gradually increasing soil salinity reduced soil water content (SWC), SOC, and soil nitrogen (N), especially in high salinity soils of coastal wetlands. Total ASs and their ratio to SOC, respectively, decreased by 90.56 and 66.35% from low salinity to high salinity soils, indicating that coastal wetlands with high salinity restrained microbial residue accumulation and microbial residue-C retention in the SOC pool. Together with redundancy analysis and path analysis, we found that SWC, pH, SOC, soil N, and glucosamine/muramic arid were positively associated with the ratio of ASs to SOC. The higher available soil resource (i.e., water, C substrate, and nutrient) increased microbial residue accumulation, promoting microbial derived-C contribution to SOC in low salinity coastal wetlands. The greatly decreased microbial residue contribution to SOC might be ascribed to microbial stress strategy and low available C substrate in coastal wetlands with high salinity concentration. Additionally, the gradually increasing salinity reduced fungal residue contribution to SOC but did not change bacterial residue contribution to SOC. These findings indicated that changed fungal residues would substantially influence SOC storage. Our study elucidates microbial contribution to SOC pool through residue reservoir in coastal wetlands and pushes microbial metabolites to a new application in global wetland SOC cycling.

Soil moisture is the major factor influencing microbial properties and nitrous oxide (N₂O) production. Agricultural soils can be probed under wetting, wet/dry alternating, and constant moisture conditions to evaluate the combined effects of early (previous) and immediate (current) moisture on N₂O emission and nitrification/denitrification. In view of the water history of upland black soil, five moisture regimes comprising different antecedent and present water holding capacity (WHC) levels were set up in the microcosm study. The 20% WHC was adopted as the initial legacy moisture, while three immediate water statuses include constant WHC, dry-wet cycle, and incremental moisture. Quantitative PCR and 16S rRNA amplicon sequencing were used to assess the impact of current and previous moisture on the bacterial community composition and abundance of nitrification/denitrification genes (amoA, nirS, and nosZ); the soil physicochemical properties, and N₂O emission were monitored. The N₂O production and nitrifying-denitrifying microbial communities were influenced by the antecedent moisture and pattern of the dry-wet cycle. The nitrifying-denitrifying microbial communities, especially members of β-/γ-Proteobacteria, Bacteroidetes and Gemmatimonadetes, in black soil were important in explaining the variation of N₂O production. The key taxonomic groups in response to the moisture alteration, e.g., Acidobacteria, Sphingobacteriia, Deltaproteobacteria, Methylobacterium, Gemmatimonas and Pseudarthrobacter, etc., were also highlighted. The soil nitrate, ammonium nitrogen, N₂O emission, nitrification/denitrification and mineralization were profoundly impacted by water regimes and showed statistically significant correlation with specific bacterial genera; the nitrite/nitrate reduction to ammonium could be boosted by high moisture. Both nitrifier denitrification and heterotrophic denitrification could be enhanced substantially when the black soil moisture was increased to above 60% WHC. These findings help evaluate the effects of the water mode on the N₂O emission from black soil, as well as the associated impacts on both soil fertility and the global environment.

As the main organic materials, straw and manure play a critical role in soil organic carbon (SOC) sequestration and crop yield in China. This meta-analysis evaluated the impact of straw and manure amendments, both individually and combined, on crop yield, SOC, and soil nutrients in China by collecting 173 studies. The findings of this study revealed that straw return and manure application increased crop yields by 14.4% and 70.4%, respectively, overall. Combined straw and manure application gained a better improvement effect than straw alone but was less effective than manure alone. Regarding the straw return results, rice straw and a 3000–6000 kg ha⁻¹ returning quantity improved crop yield, SOC, available phosphorus (AP), available potassium (AK), and total nitrogen (TN) the most; regarding the straw return form, straw incorporated into soil and biochar increased crop yield and SOC more, respectively; and <5 years and ≥5 years of straw return treatment increased crop yield and TN more, respectively. Regarding manure application, pig and chicken manure increased crop yield and TN more, respectively; a 50–80% substitution ratio and 10–20 years of duration were best for improving crop yield, SOC, AP, AK, and TN. This study highlights the importance of optimal organic amendment through straw or manure applications to achieve a win–win between crop yield and soil fertility under the requirement of sustainable agriculture.

Ecological cultivation is a promising regime for medicinal plant production. For a long time, unreasonable farming methods have threatened soil health and medicinal agriculture and restricted the sustainable development of ecological agriculture for medicinal plants. However, there is a lack of comprehensive discourse and discussion about the pros and cons of different tillage regimes. Here, the research trend and application prospects of no-tillage (NT) are comprehensively reviewed, and the ecological benefits, challenges, and opportunities of the NT system in ecological agriculture of medicinal plants are scrutinized, aiming to call for an about-face in the sustainable conservation and utilization of both phytomedicine resources and agricultural/ecological resources. An exhaustive literature search in PubMed, Bing, Scopus, and CNKI was performed to outline the research trend in conservation tillage and medicinal plants during the recent four decades. The application of NT has a long history and can reduce tillage frequency and intensity and protect soil from erosion and deterioration. NT is often combined with organic mulch to significantly reduce soil disturbance. NT and stover mulching have the advantages of saving manpower and resources and improving soil quality, crop yield, and quality. The ecological and economic benefits of NT in long-term medicinal plant cultivation could be prominent. In developing medicinal plant cultivation, competing with food crops should be avoided as much as possible, and the impact on the production of major grain crops should be minimized. Therefore, the full utilization of soil resources in forests, mountains, and wasteland is advocated, and sustainable soil utilization is the core issue in the process of land reclamation. NT and stover mulching not only inherit the traditional concept of “natural farming”, conform to the basic laws of ecology, as well as the growth characteristics of medicinal plants, but also protect the ecological environment of the production area. It would become the core strategy of ecological agriculture for medicinal plants. Our summary and discussions would help propose countermeasures to popularize NT and organic mulch, promote relevant research and scientific allocation of resources, and adapt to local conditions to achieve precise management and harmonize conservation and production of medicinal plants.

The breeding of laying hens and broilers in China has increased tremendously. Wet organic fertilizer prepared from hen manure using high-temperature container fermentation preserves high levels of nutrients and a diverse microbial community. We applied low doses of organic fertilizer to peanuts in the black soil area of China’s northeastern region. Based on the calculation of nitrogen content, treatments were set as follows: chemical fertilizer (PCF), organic fertilizer (POF, 4500 kg·ha⁻¹), and replacement of 50% chemical fertilizer with organic fertilizer (PR, 2250 kg·ha⁻¹). Compared to the plots with chemical fertilizers, the use of organic fertilizer and replacing 50% of the chemical fertilizers with organic fertilizer significantly increased peanut yields. Both the organic fertilizer and replacing 50% of the chemical fertilizers with organic fertilizer did not significantly affect the activities of the most tested soil enzymes related to carbon transformation and the absolute abundance of microorganisms. However, they did significantly enhance soil dehydrogenase and α-glucosidase. The community abundance ratio of fungi/bacteria trended downward, leading to soil with a high-fertility bacterial composition. The replacement of 50% chemical fertilizer with organic fertilizer significantly enhanced the species richness and diversity of the bacterial and fungal communities. Organic fertilizer treatment significantly increased the relative abundance of Gemmatimonas and Sphingomonas. The relative abundance of Mycobacterium in the treatment where 50% of the chemical fertilizers were replaced with organic fertilizer was significantly lower than that in the organic fertilizer treatment. PCoA results showed that the low-dose organic fertilizer treatment, replacing 50% of the chemical fertilizers with organic fertilizer, had a significant impact on the composition of soil bacterial communities.

Large nitrogen (N) losses during fertilization in agricultural production may result in energy wastage, soil and water contamination, and potentially influence crop development. Thus, with the help of a ¹⁵N-labeled tracer, we carried out a field monitoring analysis of NH₃ emissions in a long-term (9-year) conservation tillage agroecosystem of Mollisols in northeast China, in order to determine whether a no-tillage regime and four levels of stover mulching (0%, 33%, 67%, and 100%), combined with urease and nitrification inhibitors, could improve fertilizer utilization efficiency in agricultural systems by reducing ammonia volatilization. Our results showed that in comparison with ridge tillage, no-tillage with stover mulching levels of 33%, 67%, and 100% significantly reduced NH₃ emission rates and cumulative volatilization from 159.67 to 130.42 g N ha⁻¹ and ¹⁵N-NH₃ cumulative volatilization emission by 26% (on average). Furthermore, the application of urease and nitrification inhibitors significantly reduced ¹⁵N-NH₃ volatilization levels from 1.19 to 0.98 g N ha⁻¹. Our research results demonstrate that a long-term no-tillage regime and straw mulching can significantly reduce NH₃ volatilization in fertilizers. Furthermore, when combined with the use of urease and nitrification inhibitors, these practices further enhance the reduction in NH₃ volatilization. Although the volatilization of ¹⁵N-NH₃ is minimally studied in Mollisols, these findings provide a solid foundation for improving fertilizer utilization efficiency, reducing crop production costs and mitigating subsequent environmental pollution.