Soil Organic Carbon Research Articles

Treatment effects of conservation trenching on regulating and provisioning ecosystem services

United Nation Sustainable Development Goal 15.3 make a note of growing significance of management and restoration strategies for degraded land, and advocating globally for collaborative frameworks of innovative applied research and policy. Present study, quantified the impacts of the staggered contour trenching (SCT) technology in conjunction with silvi-pasture production system on regulating and provisioning ecosystem services of degraded mini-watersheds. Impacts of the SCT on hydrologic regulating ecosystem services were quantified by employing the paired watershed approach. Concept of watersheds with and without treatments was employed for computing non-hydrologic regulating and provisioning ecosystem services of the SCT in conjunction with silvi-pasture system. Results of analyses revealed that the SCT density of 505 trenches ha−1 had the highest reduction in the hydrologic regulating services namely, mean annual runoff event, runoff amount and soil loss, which were 35.5, 63.3, and 3.73%, respectively followed by 378, and 186 trenches ha−1. The highest improvement in the effective rainfall (9.9%) and effective rainfall efficiency (15.0%) was also with 505 trenches ha−1. The SCT density of 505 trenches ha−1 had retained silt 23.1 and 1.2 times higher than that of 378 and 186 trenches ha−1. The values of the post-treatment non-hydrologic regulating services of 505 trenches ha−1 were many folds higher compare to other trenching densities. Improvement in the non-hydrologic regulating services of the available -nitrogen, -potash and -potassium, and soil organic carbon values of the post-treatment of 505 trenches ha−1 were 36.7, 44.2, 25.8, and 25.0% than their pre-treatment values, respectively. Provisioning ecosystem services in term of the yields of the wood biomass of the Acacia nilotica and the Cenchrus ciliaris were the highest with 505 trenches ha−1 than the control (no trench) by 166.2 and 21.5%, respectively. Study indicated that 505 trenches ha−1 SCT density in the silvi-pasture production system was the best practices in conserving and maintaining the degraded land ecosystem services. These findings would be very supportive to the policy makers and degraded land managers for reclaiming and improving the sustainability and ecosystem functioning of the degraded land ecosystem for achieving the SDG 5.3 and maintaining the land degradation neutrality.

Atmospheric Transport of Semivolatile Organic Contaminants across an Urban-Alpine Boundary.

Current understanding of atmospheric transport of semivolatile organic contaminants (SVOCs) in alpine areas is limited due to complex meteorology and topography. Salt Lake City, Utah borders protected wilderness areas in the Wasatch Mountains, exhibiting a useful model system in which an urban source of SVOCs, including polyaromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), is located directly adjacent to an alpine sink. Our objective was to investigate the impacts of topographical features on the transport and deposition of SVOCs across an urban-alpine boundary. To do so, we measured PAHs and PCBs in soils along a transect starting at the urban-mountain interface and extending into an alpine wilderness, crossing several prominent ridgelines. Concentrations of PAHs and PCBs in soils were heavily influenced by soil organic carbon content, air temperature, and proximity to the urban boundary. However, the role of source proximity was only revealed after normalizing concentrations in soil to organic carbon content and air temperature. Further, we present evidence of SVOC emission/deposition cycles driven by diurnal alpine winds that do not extend past topographical features. Our results illustrate the roles of multiple competing processes on SVOC transport in alpine systems and their importance at an urban-alpine boundary.

Independent effects of tree diversity on aboveground and soil carbon pools after six years of experimental afforestation.

Planting diverse forests has been proposed as a means to increase long-term carbon (C) sequestration while providing many co-benefits. Positive tree diversity-productivity relationships are well established, suggesting more diverse forests will lead to greater aboveground C sequestration. However, the effects of tree diversity on belowground C storage have the potential to either complement or offset aboveground gains, especially during early stages of afforestation when potential exists for large losses in soil C due to soil decomposition. Thus, experimental tests of the effects of planted tree biodiversity on changes in whole-ecosystem C balance are needed. Here, we present changes in above- and belowground C pools 6 years after the initiation of the Forests and Biodiversity experiment (FAB1), consisting of high-density plots of one, two, five, or 12 tree species planted in a common garden. The trees included a diverse range of native species, including both needle-leaf conifer and broadleaf angiosperm species, and both ectomycorrhizal and arbuscular mycorrhizal species. We quantified the effects of species richness, phylogenetic diversity, and functional diversity on aboveground woody C, as well as on mineral soil C accumulation, fine root C, and soil aggregation. Surprisingly, changes in aboveground woody C pools were uncorrelated to changes in mineral soil C pools, suggesting that variation in soil C accumulation was not driven by the quantity of plant litter inputs. Aboveground woody C accumulation was strongly driven by species and functional identity; however, plots with higher species richness and functional diversity accumulated more C in aboveground wood than expected based on monocultures. We also found weak but significant effects of tree species richness, identity, and mycorrhizal type on soil C accumulation. To assess the role of the microbial community in mediating these effects, we further compared changes in soil C pools to phospholipid fatty acid (PLFA) profiles. Soil C pools and accumulation were more strongly correlated with specific microbial clades than with total microbial biomass or plant diversity. Our results highlight rapidly emerging and microbially mediated effects of tree biodiversity on soil C storage in the early years of afforestation that are independent of gains in aboveground woody biomass.

Increasing tree phylogenetic diversity stimulates microbial functional potential in a subtropical forest

Abstract Soil microbial functions are closely related to ecosystem productivity, carbon sequestration and their responses to global change. Tree phylogenetic diversity has been found to impact microbial community composition, diversity, and functions, but how it modulates the linkage between microbial community facets and functions remains unclear. Here, 45 plots covering a natural gradient of tree phylogenetic diversity (TPD) were selected in a subtropical forest of southwest China to explore how increasing TPD impacts soil microbial community facets and microbial functional potential. The microbial functional potential was evaluated based on the abundances of carbon, nitrogen, and phosphorus cycling-related functional genes. Soil fungal alpha diversity increased significantly, but bacterial alpha diversity did not change as TPD increased. Both soil microbial network complexity and stability improved significantly with increasing TPD. Ultimately, increasing TPD promoted soil microbial functional potential by stimulating soil carbon and nitrogen availability, microbial keystone diversity, and network stability collectively. These findings emphasize the critical roles of keystone taxa and network stability as microbial factors in stimulating soil microbial function in response to increasing TPD. Therefore, it is strongly recommended to increase TPD in order to stimulate soil microbial functions and other ecosystem functions when implementing afforestation or ecological restoration projects.

Perturbation of soil organic carbon induced by land-use change from primary forest

Abstract The impact of land-use change (LUC) on soil organic carbon (SOC) has been a wide concern of land management policymakers because CO2 emissions induced by LUC have been the second largest carbon source worldwide. However, due to insufficient data quality and limited biome coverage, a global big picture of the impact of LUC on SOC is still not clear. This study conducted a meta-analysis on 288 independent observations sourced from 62 peer-reviewed papers to provide a global summary of the change in SOC after the conversion of primary forests into other land-use types. The conversion of primary forest to cropland resulted in the most severe SOC loss (-33.2%), followed by conversion into plantation forests (-22.3%) and secondary forests (-19.1%). Nonetheless, SOC increased by 9.1% after a conversion from primary forests into pasture. More SOC loss was found at sites with lower precipitation for primary forests converted to cropland and plantation forests. The SOC loss decreased consistently with increasing mean annual temperature (MAT) for all four types of LUC. Moreover, the loss of SOC tended to worsen over time when primary forests are converted to cropland or plantation forests. In contrast, SOC loss recovered over time following conversion to secondary forests. The gain of SOC gradually increased over time after conversion to pastures. To conclude, the changes in SOC are related not only to the land-use type but also to precipitation, temperature and turn years after LUC. Due to limited data, this study focuses on soil profiles within 30 cm depth, and future research should explore SOC dynamics induced by LUC at greater depths. Overall, cases of SOC loss of approximately 30% following deforestation were very common (except for conversion to pasture). Thus we suggest that the loss of SOC following LUC should be carefully considered and monitored in land management.

Effects of Compost Application of Green Waste on Soil Properties: A Meta-Analysis

Objective: With the accelerating urbanization process, the garden area is gradually expanding, and the production of green waste is also increasing. Composting green waste can not only reduce environmental pollution caused by incineration and landfill and improve the utilization efficiency of resources but also improve the soil and increase soil productivity. The study aims to investigate the comprehensive impact of green waste compost (GWC) application on soil nutrient conditions. Through comprehensive data analysis, the impact of compost application of green waste on soil properties was revealed as a reference for compost application and fertilizer reduction. Methods: Based on meta-analysis, we quantitatively investigated the response of soil properties to the application of green waste, collected published experimental data, and integrated 25 domestic and international literature to analyze the effects of different soil properties on soil nutrients. Literature was used to analyze the impact of different application rates of GWC on the physicochemical properties of soils with varying pH levels. The results were compared to control conditions with no GWC application. Results: The application of significantly improved soil quality by reducing soil bulk density and increasing the levels of soil organic matter, organic carbon, total nitrogen, available phosphorus, available potassium, and dehydrogenase activity. The increases in available potassium and soil organic carbon were consistently significant across all subgroups. However, the effects on available phosphorus and organic matter varied in significance depending on initial soil pH. Soil bulk density was influenced by the GWC content, while dehydrogenase activity showed significant effects only when initial soil pH was ≥8. Total nitrogen levels were significantly impacted by GWC application in soil with an initial pH of <8 and at GWC contents of ≥50%. Conclusion: The application of green waste compost demonstrates a positive effect on soil improvement. This study provides a comprehensive database that supports the use of GWC in enhancing soil quality and reducing the need for chemical fertilizers.

The conversion of biomass to biochar decreases soil organic and inorganic carbon-derived CO2 emissions under different water conditions in karst regions

Due to the unique geological background and climatic condition, karst soils in southwest China are mainly developed on carbonate rocks and accompanied by frequent dry-wet alternations. Therefore, the effects of biomass (BS) and biochar (BC) on the soil carbon pools (especially inorganic carbon) in karst regions are different from those in non-karst regions. In order to understand the responses of soil organic carbon (SOC) and soil inorganic carbon (SIC)-derived CO2 emissions to BS and BC amendments under different water conditions in karst regions, a microscopic study under dry-wet alternate (DW) and constant moisture (CM) conditions was established to investigate the stability of BC, BS, and their effects on SOC and SIC pools by isotope double-labeling methods. Results showed that the contribution rates of SOC and SIC to soil CO2 emissions were 51.55 %–99.52 %, 0.48 %–48.45 % and 60.55 %–97.72 %, 2.28 %–39.45 % under DW and CM conditions, respectively. Compared with the control, BS application under different water conditions increased SOC and SIC-derived CO2 emissions by 929.78˗1443.39 % and 169.69˗335.71 %, respectively. However, BC amendment significantly decreased SOC and SIC-derived CO2 emissions, especially in the DW condition. The mean residence time (the inverse of the decomposition rate) of BC in karst soils under different conditions ranged from 657 to 3105 years, which was much higher than those of BS (7˗18 years). Therefore, the conversion of BS to BC in karst regions enhances carbon sequestration due to its stability of recalcitrant carbon, the decrease of SOC and SIC- derived CO2 emissions. This study is helpful to understand the quantification of CO2 sources from calcareous soils and elucidate the environmental behaviors and carbon sequestration potentials of BC or BS amendments in karst regions.

Alpine SOC and Microbial Community Assembly Were Buffered Through Soil Pore Structure Along an Altitudinal Gradient

ABSTRACTElevation changes influence various environmental factors including cloudiness, atmospheric density, and temperature. Previous studies on the effects of elevation on microbial communities and soil organic carbon (SOC) yielded inconsistent results. This study tried to reveal the distribution patterns of microbial communities and SOC concentrations, as well as their interactions with soil structure along an elevational gradient in the alpine region. We investigated six typical ecosystems along an elevational gradient on the north‐eastern Qinghai‐Tibet Plateau. Phospholipid fatty acid (PLFA) analysis and X‐ray computed tomography (CT) methods were used to quantify microbial abundance and pore structure of soils, respectively. The results demonstrated that SOC content and total PLFAs peaked in the meadow ecosystem. In the subsoil, total PLFAs, fungal, and bacterial PLFAs followed the U‐shape pattern with increasing elevation. In both topsoils and subsoils, the surface area density of pores increased with elevation, and it was found to be positively correlated with SOC and microbial abundance. Soil structure mainly affects the input and adsorption of root nutrients by altering the pore surface area, thereby regulating the enrichment of microorganisms. The impact of pore structure on microbes were more obvious in the topsoil than in the subsoil. Interactions among pore structure, soil properties, and environmental factors jointly affects the microbial communities, demonstrating that elevation indirectly affects microbial communities through soil resource regulation.

Effect of Caragana microphylla Lam. on Desertified Grassland Restoration

Background: The restoration of the degraded sandy grasslands in Hulun Buir is crucial for maintaining the local ecological balance and sustainable development. Caragana microphylla Lam., a shrub species widely employed in the restoration of sandy vegetation. It is essential to understand its impact on the understory vegetation and soil properties during this process. Methods: This study employed ANOVA, Pearson correlation, and redundancy analysis to systematically analyze the impact of C. microphylla on the three critical stages of desertified grassland vegetation recovery: semi-fixed dunes, fixed dunes, and sandy grasslands. It provided strategies for the restoration of desertified grassland vegetation and offered additional theoretical evidence for the role of vegetation in promoting the recovery of sandy lands. Results: (1) As the degree of vegetation recovery in desertified grasslands increases, the species richness of understory vegetation, Shannon–Wiener index, community height, and biomass also increase. Both the community height and biomass within shrublands are higher than outside, with species richness within the shrublands being higher than outside during the semi-fixed and fixed-sand land stages. (2) In both the 0~10 cm and 10~20 cm soil layers, soil water content showed an increasing trend, peaking in the sandy grassland stage (1.2%), and was higher within the shrublands than outside. The soil water content at 10~20 cm was higher than in the 0~10 cm layer. In both layers, clay and silt content gradually increased with the degree of vegetation recovery in the sandy land, and higher within the shrublands than outside, while the opposite was true for sand content. (3) In both soil layers, soil organic carbon gradually increased with the degree of vegetation recovery, peaking in the sandy grassland stage (4.12 g·kg−1), and was higher within the shrublands than outside. Total nitrogen increased from the semi-fixed-sand land stage to the fixed-sand land stage, with higher levels within the shrublands than outside at all stages. Soil pH within the shrublands decreased as the degree of vegetation recovery increased. There was no significant change in the total phosphorus content. (4) In both soil layers, soil physicochemical characteristics accounted for 59.6% and 46.9% of the vegetation changes within and outside the shrublands, respectively, with the main influencing factors being the soil particle size, total nitrogen, soil water content, and soil organic carbon. Conclusions: In the process of sandy grassland restoration, C. microphylla facilitates the growth and development of vegetation by enhancing the underlying soil physicochemical properties, specifically regarding the soil particle size distribution, soil water content, soil organic carbon, and total nitrogen.

Soil-Based Emissions and Context-Specific Climate Change Planning to Support the United Nations (UN) Sustainable Development Goal (SDG) on Climate Action: A Case Study of Georgia (USA)

Soil-based emissions from land conversions are often overlooked in climate planning. The objectives of this study were to use quantitative data on soil-based greenhouse gas (GHG) emissions for the state of Georgia (GA) (USA) to examine context-specific (temporal, biophysical, economic, and social) climate planning and legal options to deal with these emissions. Currently, 30% of the land in GA has experienced anthropogenic land degradation (LD) primarily due to agriculture (64%). All seven soil orders were subject to various degrees of anthropogenic LD. Increases in overall LD between 2001 and 2021 indicate a lack of land degradation neutrality (LDN) in GA. Besides agricultural LD, there was also LD caused by increased development through urbanization, with 15,197.1 km2 developed, causing midpoint losses of 1.2 × 1011 kg of total soil carbon (TSC) with a corresponding midpoint social cost from carbon dioxide (CO2) emissions (SC-CO2) of USD $20.4B (where B = billion = 109, $ = U.S. dollars (USD)). Most developments occurred in the Metro Atlanta and Coastal Economic Development Regions, which indicates reverse climate change adaptation (RCCA). Soil consumption from developments is an important issue because it limits future soil or forest carbon (C) sequestration potential in these areas. Soil-based emissions should be included in GA’s carbon footprint. Understanding the geospatial and temporal context of land conversion decisions, as well as the social and economic costs, could be used to create incentives for land management that limit soil-based GHG emissions in a local context with implications for relevant United Nations (UN) initiatives.

Characteristics of organic carbon in tobacco-growing soils with different pH

This paper deal with the analysis of the relationship between acidity and alkalinity with organic carbon structure and humus components of tobacco-growing soils in Tengchong city. Under the same level of organic matter and nutrient content, soils with different pH values in Tengchong city were selected for the investigation. Results showed that the HA/FA values of the soil with low organic matter content gradually decreased with increasing pH, indicating a higher content of active carbon components and a lower content of stable carbon components in the soils. In soils with high organic matter content, pH value showed a highly significant negative correlation with HA/FA and PQ values. With increasing acidity, HA/FA became higher, and humus components with high stability increased. At the same level of organic matter content, the infrared A2920/A1630 ratio gradually increased with increasing pH. It indicates that at a certain pH range and the same level of organic matter content, the stable humus component increases, and the soil pH value decreases. Bangladesh J. Bot. 53(3): 745-755, 2024 (September) Special

Weathering of Buried Standard Pieces of Serpentine under Varied Soil Treatments and Relevant Analysis of Microbial Community Structure

Carbon sink processes related to the weathering of silicate minerals are often accompanied by physical, chemical, and biological effects. In particular, plant-microbe synergistic effects are important for soil mineral weathering, but relevant correlation analyses and quantitative studies remain sparse. In this research, a standard serpentine test specimens (STSs) with specific specifications were used to study serpentine weathering under different environmental conditions (abiotic or biotic) and correlated it with the microbial community structure under the growth of Setaria viridis. The results showed that the environment with growing S. viridis had the strongest weathering capacity for STSs, which was 35 times higher than that of the abiotic environment group, and a significant increase in soil inorganic and organic carbon contents compared with the abiotic environment and the environment without plant growth. The bacteria with strong weathering ability were enriched in the soil of around STSs, such as Pseudomonas spp. and Sphingomonas spp. In addition, the fungal community of Ascomycetes is also heavily enriched, accelerating STSs weathering. The addition of bacterial agent (Bacillus subtilis) further promoted the STSs weathering under the growth conditions of S. viridis. The soil surrounding the buried STSs was also enriched with heavy metal tolerant Massilia spp. and disease suppressing Lysobacter spp., while the abundance of fungi functionally associated with pathotypes was reduced, thereby benefiting plant growth. This study provides basic information for the serpentine bio-weathering coupled with carbon sequestration by using plant-microbe synergistic effects.

Post-Extractivism and Bioeconomy: An Experimental Analysis of Combustion and Pyrolysis Processes as Alternatives to Add Value to Agro-Residues (Coffee Husks) Generated in Farmer Cooperatives of the Ecuadorian Amazon

A post-extractivist development model for communities in the Amazon that is not based on non-renewable resource extraction demands the study and demonstration, in the field, of alternative economic activities that add value to currently generated residual biomass. Following the principles of bioeconomy, this study presents an experimental analysis of a retort burner and a pilot-scale auger-type pyrolysis reactor used to convert coffee husks generated in a collection and post-harvesting center of a farmer’s cooperative into thermal energy and biochar, respectively. This study shows that coffee husks, whether used as feedstock for combustion or pyrolysis processes, can supply the thermal energy required by the post-harvesting processes. The combustion or pyrolysis of coffee husks avoids its accumulation and decomposition while replacing fossil fuels used in post-harvesting operations, reducing costs and making farmers independent of fossil fuel subsidies. Unlike combustion (11,029.4 mg/Nm3), the CO concentration in the flue gas during the pyrolysis process was 458.3 mg/Nm3, which is below the eco-design standard of 500 mg/Nm3. According to the European Biochar Certificate, carbon content (67.4 wt%) and H/Corg, O/Corg (0.6 and 0.1, respectively) are within the typical values of biochars used for soil amendment and carbon sequestration. Nonetheless, the concentration of polycyclic aromatic hydrocarbons must be assessed to fully regard this material as biochar. Finally, further studies are required to assess the ability of cooperatives to generate and trade carbon credits linked with the application of biochar in their cropping systems.

Soil Recycling of Waste Biomass in the Production of Malus domestica Fruit Tree Seedlings

The production of fruit tree seedlings generates waste wood biomass, which results from the pruning of budded rootstocks in the first year of the two-year production cycle. This study proposes a new method of managing this biomass by recycling the wood chips (2, 3 and 5 t ha−1) back into the soil. The impact of different wood chip doses on selected physicochemical soil properties after the production process (especially soil organic carbon content (SOC), as well as the quantity and quality of the produced Malus domestica fruit tree seedlings, was determined. The recycling of waste biomass contributed to enriching the soil with additional components, mainly organic carbon with the potential for biotransformation into humic substances. The applied doses of wood chips, in amounts of 2, 3, and 5 t ha−1, resulted in an increase in SOC content compared to the control by 21.5%, 22.5%, and 35.8%, respectively. Additionally, the recycling of waste biomass introduced other compounds important for plant growth and development into the soil, particularly iron, zinc, magnesium, and manganese. It should be noted that the proposed method of managing waste biomass generated during the apple tree seedling production stage resulted in reduced production costs while maintaining high production indices.

Effects of chemical fertilizer with rice straw on the carbon compositions of tobacco-planting soil

This study explored the changes in carbon components of tobacco-planting soil by the application of rice straw as organic materials to replace chemical fertilizers partially. Flue-cured tobacco was applied to the soil as base fertilizer to investigate the mineralization of soil organic carbon during its growing period. At 0 d, the humic acid carbon (HA-C), humin carbon (HM-C), HU ratio, PQ value and HM-C/(HA-C + FA-C) are 31.67, 31.40, 60.05, 28.01 and 27.75%, respectively which is higher than those of chemical fertilizer alone. At 30 d, the humus carbon (HE-C), HA-C, and fulvic acid carbon (FA-C) were 29.41, 20.97 and 30.49%, respectively. At 90 d, the A2920/1630 values were 227.43 and 232.32% higher than chemical fertilizer. Application of rice straw and decomposed rice straw with less fertilizer can increase the content of soil organic matter, HA-C, HM-C and FA-C in the tobacco-planting soil. This method increases the content of aliphatic chain hydrocarbons and reduces the amount of aromatic carbon, thus increasing aliphatic properties and decreasing the aromatic properties of soil. The treatment with chemical fertilizer reduction with decomposed rice straw also accelerates the formation and accumulation of stable components such as humic acid and humin and significantly improves the humification of soil humus. Bangladesh J. Bot. 53(3): 811-822, 2024 (September) Special

Restoring degraded lands: the role of sewage sludge in modulating soil carbon and nitrogen dynamics

Sewage sludge presents significant amounts of organic matter and nutrients and is frequently considered an alternative input for recovering degraded soils. In this scenario, this study aimed to evaluate the impacts of disposing of increasing doses of sewage sludge on the dynamics of C and N in the soil of a degraded area. After the application of five doses of sewage sludge (0, 50, 100, 200, and 400 t ha-1) were evaluated over time (30, 90, 180, 270, and 360 days), the contents of soil C and N, microbial biomass, light organic matter, and humic fractions of soil organic matter. The results showed that sewage sludge contributed to the quality and recovery of degraded soil by providing increases in soil organic C, total N, nitrate, and ammonia contents, microbial biomass C and N, light organic matter, as well as in the C and N stocks in humic substances, especially in humin. Most of the increases in these variables associated with C and N dynamics remained even one year after the application of sewage sludge. The soil quality improvement demonstrates the potential of using sewage sludge in projects to recover degraded areas as an alternative for its final disposal.

Asymmetric winter warming reduces microbial carbon use efficiency and growth more than symmetric year-round warming in alpine soils

Asymmetric seasonal warming trends are evident across terrestrial ecosystems, with winter temperatures rising more than summer ones. Yet, the impact of such asymmetric seasonal warming on soil microbial carbon metabolism and growth remains poorly understood. Using 18O isotope labeling, we examined the effects of a decade-long experimental seasonal warming on microbial carbon use efficiency (CUE) and growth in alpine grassland ecosystems. Moreover, the quantitative stable isotope probing with 18O-H2O was employed to evaluate taxon-specific bacterial growth in these ecosystems. Results show that symmetric year-round warming decreased microbial growth rate by 31% and CUE by 22%. Asymmetric winter warming resulted in a further decrease in microbial growth rate of 27% and microbial CUE of 59% compared to symmetric year-round warming. Long-term warming increased microbial carbon limitations, especially under asymmetric winter warming. Long-term warming suppressed the growth rates of most bacterial genera, with asymmetric winter warming having a stronger inhibition on the growth rates of specific genera (e.g., Gp10, Actinomarinicola, Bosea, Acidibacter, and Gemmata) compared to symmetric year-round warming. Bacterial growth was phylogenetically conserved, but this conservation diminished under warming conditions, primarily due to shifts in bacterial physiological states rather than the number of bacterial species and community composition. Overall, long-term warming escalated microbial carbon limitations, decreased microbial growth and CUE, with asymmetric winter warming having a more pronounced effect. Understanding these impacts is crucial for predicting soil carbon cycling as global warming progresses.

Multi-omics analysis of soil microbiota and metabolites in dryland wheat fields under different tillage methods

No-tillage and subsoiling can improve soil aggregate structure and realize a synergistic effect of soil carbon and nitrogen retention compared with deep tillage. This study aimed to investigate the effects of different tillage methods on the microbiome and metabolites in wheat rhizosphere. Results indicated that no significant differences in the diversity of soil bacterial and fungal communities were observed among the tillage methods. Analysis revealed that no-tillage enriched specific genera such as Cryptosporangium, Crossiella, Rhodothermaceae, Leptothrix, Stilbella, Diutina, and Pyrenochaetopsis, while subsoiling was associated with Rubrobacter, Latescibacteraceae, Nitrospira, Rokubacteriales, and Ctenomyces. Deep tillage, on the other hand, showed significant associations with Nocardia, Aeromicrobium, Sphingopyxis, Cordyceps, and Subulicystidium. Metabolomic analysis identified differential metabolites involved in various pathways, including the biosynthesis of plant secondary metabolites, ABC transporters, and starch and sucrose metabolism. Correlation analysis revealed a significant interaction between microorganisms and metabolites in wheat rhizosphere. Bacteria at the genus level exhibited greater associations with differential metabolites. In conclusion, different tillage practices can alter the composition of microbial communities and metabolites in wheat rhizosphere, and their interactions may affect soil fertility and wheat growth.

Effects of environmentally friendly soil remediation materials on soil quality and maize production

In the precent, the reclaimed raw soil of newly renovated abandoned homestead was considered as the research object, and study the effects of different environmentally friendly soil remediation material combinations on the quality of reclaimed raw soil and maize crop production. A total of 6 improved material treatments were set up, including decomposed chicken manure(YJ), fly ash(FMH), ferrous sulfate curing agent(SHJ), ferrous sulfate curing agent+organic fertilizer (SYJ), fly ash+decomposed chicken manure(FYJ), and control treatment(CK). The research results showed that, the organic carbon content and water storage of new reclaimed raw soil exhibited a significant increasing trend after the application of different environmentally friendly modified materials(P < 0.05). Among them, the organic carbon and water storage of reclaimed soil under FYJ improved, which increased by 132.3 and 14.4 %, respectively compared with CK. During the growth period of summer maize, the plant height and yield exhibited a trend of FYJ> SYJ> YJ> FMH> SHJ> CK. The yield of maize under SYJ and FYJ treatments increased by 38.8 and 53.4 %, respectively, compared with CK. The appropriate combination of environmentally friendly soil remediation materials is helpful to improve the quality of new reclaimed raw soil, promote soil carbon sequestration, increase the comprehensive utilization rate of waste resources, increase the production performance of crops, and help rural revitalization and beautiful rural construction. Bangladesh J. Bot. 53(3): 673-679, 2024 (September) Special

Perennial crops shape the soil microbial community and increase the soil carbon in the upper soil layer

Soil biodiversity is threatened by intensive agriculture that relies on annual grain crop production, thus leading to a decline in soil functions and ecosystem services. Perennial grain crops have a positive impact on the soil microbial community, but the responsive microbial groups and the magnitude of their response remain uncertain. To elucidate this, we analysed soil microbial biomass and community composition, bacterial growth and soil total carbon in five crops: organic perennial intermediate wheatgrass (IWG, Thinopyrum intermedium, Kernza®), organic IWG-alfalfa intercrop, organic biennial grass-legume mixture, organic annual wheat or rye and conventional annual wheat. The analysis was carried out at three time points under two growing seasons at four different soil depths. Five years after establishment, IWG had greater amounts of soil total fungi and bacteria, and of arbuscular mycorrhizal (AM) fungi, saprotrophic fungi, gram-negative (G−) and gram-positive (G+) bacteria compared to annual wheat. Crop perenniality influenced the soil microbial community structure although precipitation, soil temperature and water content were the main drivers of the patterns of and temporal variations in the microbial community. Perennial crops, with reduced tillage and low nitrogen input management increased the proportions of fungi relative to bacteria, AM fungi to saprotrophic fungi, G− bacteria to G+ bacteria, and the growth rate of total bacteria. This resulted in a more active soil microbial community with higher microbial biomass than annual wheat and contributed to the increased soil total carbon storage in the 0–5 cm soil layer in a humid continental climate. The findings emphasize the importance of combining a no tillage strategy with long-term vegetation cover to increase soil quality.