The effects of continuous planting on the growth of Casuarina equisetifolia (C. equisetifolia) have severely restricted the sustainable development of the industry. In this study, we investigated the diversity and functional changes of bacteria and fungi in the rhizosphere soil of continuously planted C. equisetifolia and their effects on soil nutrient transformation and C. equisetifolia growth. The results showed that after continuous planting, C. equisetifolia growth was significantly inhibited, the activities of nutrient transformation-related enzymes in rhizosphere soil were reduced, available nutrient content of the soil decreased, and soil bacterial diversity decreased, while fungi diversity increased. After continuous planting, 9 genera of significantly altered characteristic bacteria in the rhizosphere soil of C. equisetifolia were functionally enriched in animal parasites or symbionts, aromatic compound degradation, and nitrate reduction, with contributions mainly from the 3 characterisic bacteria such as Planctopirus, Bacillus, and Acinetobacter. After continuous planting, 7 genera of significantly altered characteristic fungi in the rhizosphere soil of C. equisetifolia were functionally enriched in soil saprotroph, lichen parasite, undefined saprotroph, endophyte, animal pathogen, wood saprotroph, litter saprotroph and plant pathogen, with contributions mainly from the 6 characteristic fungi such as Aspergillu, Fusarium, Saitozyma, Tolypocladium, Mortierella, and Funneliformis. Functional analysis and PLS-SEM equation analysis showed that the growth inhibition of C. equisetifolia due to continuous planting was the result of the joint action of the characteristic bacteria and fungi, but there was a difference between the functions of the two. The function of characteristic bacteria was mainly to provide conditions for the propagation of pathogenic organisms, which reduced soil nutrient content and hindered nutrient uptake by C. equisetifolia. The function of characteristic fungi was primarily to damage soil texture, nourish pathogenic bacteria to infest C. equisetifolia, and damage the root system to inhibit nutrient uptake. Characteristic bacteria and fungi together accelerated the effect of continuous planting on the growth of C. equisetifolia. This study provides an important reference for the cultivation regulation of continuously planted C. equisetifolia.

Permafrost regions play an important role in global carbon and nitrogen cycling, storing enormous amounts of organic carbon and preserving a delicate balance of nutrient dynamics. However, the increasing frequency and severity of wildfires in these regions pose significant challenges to the stability of these ecosystems. This review examines the effects of fire on chemical, biological, and physical properties of permafrost regions. The physical, chemical, and pedological properties of frozen soil are impacted by fires, leading to changes in soil structure, porosity, and hydrological functioning. The combustion of organic matter during fires releases carbon and nitrogen, contributing to greenhouse gas emissions and nutrient loss. Understanding the interactions between fire severity, ecosystem processes, and the implications for permafrost regions is crucial for predicting the impacts of wildfires and developing effective strategies for ecosystem protection and agricultural productivity in frozen soils. By synthesizing available knowledge and research findings, this review enhances our understanding of fire severity's implications for permafrost ecosystems and offers insights into effective fire management strategies.

Acid rain and nitrogen deposition resulting from fossil fuel combustion and atmospheric NH3 enrichment have inflicted significant damage to ecosystems on a global scale. However, their specific impacts on forest soil ecosystems, particularly in soil carbon (C), nitrogen (N), and phosphorus (P) cycling, remain unclear. For this study metagenomic sequencing was employed to study the effects of simulated acid rain and nitrogen deposition on microbial functional genes in a subtropical plantation in the Yangtze River Delta region. Our findings indicated that acid rain and nitrogen deposition did not have significant impacts on overall functional Shannon diversity. However, acid rain treatments did alter microbial functional structures, particularly as relates to C, N, and P cycling. Notably, the soil pH had a significant correlation with microbial functional profiles. In the absence of nitrogen deposition, acid rain led to an increase in the relative abundance of starch and carbon monoxide (CO) oxidation processes, while reducing the relative abundance of multiple systems and reductive tricarboxylic acid (rTCA) pathway processes. Further, acid rain decreased the relative abundance of nitrogen fixation and nitrification processes, as exemplified by hao, nirK, and norZ genes, while increasing the relative abundance of norC and narI genes. Additionally, acid rain was associated with a decrease in the relative abundance of P starvation regulation and inorganic P solubilization processes. However, N deposition did not have a significant effect on microbial functional processes related to C, N, and P cycling. Our study emphasized the negative impacts of short-term acid rain on soil N and P cycling in a subtropical plantation, which surpassed that of short-term N deposition.

The seasonal coupling of plant and soil microbial nutrient demands is crucial for efficient ecosystem nutrient cycling and plant production, especially in strongly seasonal alpine ecosystems. Yet, how these seasonal nutrient cycling processes are modified by climate change and what the consequences are for nutrient loss and retention in alpine ecosystems remain unclear. Here, we explored how two pervasive climate change factors, reduced snow cover and shrub expansion, interactively modify the seasonal coupling of plant and soil microbial nitrogen (N) cycling in alpine grasslands, which are warming at double the rate of the global average. We found that the combination of reduced snow cover and shrub expansion disrupted the seasonal coupling of plant and soil N-cycling, with pronounced effects in spring (shortly after snow melt) and autumn (at the onset of plant senescence). In combination, both climate change factors decreased plant organic N-uptake by 70% and 82%, soil microbial biomass N by 19% and 38% and increased soil denitrifier abundances by 253% and 136% in spring and autumn, respectively. Shrub expansion also individually modified the seasonality of soil microbial community composition and stoichiometry towards more N-limited conditions and slower nutrient cycling in spring and autumn. In winter, snow removal markedly reduced the fungal:bacterial biomass ratio, soil N pools and shifted bacterial community composition. Taken together, our findings suggest that interactions between climate change factors can disrupt the temporal coupling of plant and soil microbial N-cycling processes in alpine grasslands. This could diminish the capacity of these globally widespread alpine ecosystems to retain N and support plant productivity under future climate change. Seasonal transfers of nutrients between plants and soil microbes are crucial for nutrient retention in alpine ecosystems. Here, we show that two important climate change factors in alpine ecosystems, reduced snow cover and shifts in vegetation, interactively disrupt these seasonal transfers of nutrients. Future climate change could therefore diminish the capacity of globally widespread alpine ecosystems to retain nutrients, with far-reaching consequences for nutrient cycling and plant productivity.image

The increasing energy required to synthesize inorganic fertilizers warrants more sustainable soil amendments that produce comparable crop yields with less environmental damage. Duckweed, a prolific aquatic plant, can not only sequester carbon dioxide through photosynthesis, but also hyperaccumulate nutrients from its environment and upcycle them into valuable bioproducts. In this study, dried duckweed, grown on treated wastewater treatment plant effluent, was utilized as a fertilizer for a variety of crops (beet, tomato, kale, and sorghum). Comparative experiments examined the effect of duckweed, inorganic fertilizer, and a 40-60 mix of both on crop yield and nutrient fate in the plants, soil, and leachate. Comparable yields of beet, tomato, and sorghum were generated with duckweed and inorganic fertilizer. Duckweed significantly enhanced phosphorus (P) uptake in sorghum, exhibiting a P use efficiency level of 18.48%, while the mix treatment resulted in the highest P use efficiencies in beet and tomato. Duckweed-amended beet and kale systems also increased residual soil N (0.9% and 11.1%, respectively) and carbon (4.5% and 16.6%, respectively). Linear regression models developed using the data collected from all crops confirmed that duckweed can be used as a substitute for inorganic fertilizer without negative effects to food yield or nutritional quality.

Soil arthropods can affect plant growth and aboveground interactions directly via root herbivory and indirectly through nutrient cycling and interactions with soil microorganisms. Research on these effects of soil arthropods has focused on a few taxa within natural systems, largely neglecting agroecosystems and arthropod community-level effects. This study investigated the effects of soil arthropod communities from cereal-based agroecosystems on wheat plant growth and above-belowground interactions. Nutrient cycling and wheat growth were measured in a greenhouse microcosm experiment using field-collected agricultural soils from two rotational schemes with and without their soil arthropod communities. The effects of soil arthropods on aboveground phytohormones and colony growth of an aphid [Metopolophium festucae cerealium (Stroyan)] infesting the plants were measured. Wheat grown in soils with arthropod communities had significantly greater root (+ Arth mean: 0.15 +/- 0.01 g; - Arth mean: 0.06 +/- 0.01 g; F-1,F-54 = 72.34, p 0.05), was significantly greater on wheat grown in soils with arthropods. Aphids, in turn, modified the effects of soil arthropods on root architecture and increased the abundance of soil arthropods. Wheat grown in soils with arthropods had increased levels of stress- and defense-related phytohormones in response to aphid herbivory, while phytohormones of wheat plants grown in soils without arthropods did not differ with aphid presence. Soil arthropod communities may help plants defend against herbivores aboveground by facilitating phytohormone induction while offsetting costs by increasing soil nutrients and modifying plant growth. By using taxonomically diverse field-collected soil arthropod communities from agroecosystems, this study showed that community-level effects on plant growth are more complex and dynamic than the effects of any single taxon, such as Collembola, illustrating that interactions within communities can produce emergent properties that alter the net effect of soil arthropods on plant growth. The results indicate that community-level effects of soil organisms should be considered as part of sustainable plant production and protection strategies.

PurposeThe health of rhizosphere soil microorganisms is an important indicator to evaluate soil quality. Therefore, understanding the response of rhizosphere soil microorganisms to tobacco crop succession is crucial for promoting the sustainable development of agriculture.MethodsThe microbial diversity and community structure of rhizosphere soil in continuous cropping and non-cropped tobacco for 7 years were analyzed by the Illumina platform.Result(1) Continuous cropping tobacco cause rhizosphere soil acidification and reduction in alkaline nitrogen (AN) and soil organic matter (SOM). (2) Continuous cropping tobacco reduces the diversity of rhizosphere soil microbial communities, increasing harmful functional microorganisms and declining beneficial ones. (3) The abundance of bacteria that perform nitrification and saprophytic fungi in the rhizosphere soil of continuous cropping areas decreases, inhibiting carbon and nitrogen cycling processes. (4) The composition and diversity of the soil rhizosphere microbial community are affected by the imbalance in the physicochemical property of the rhizosphere.ConclusionContinuous cropping tobacco cause rhizosphere soil acidification and nutrient imbalance, and the carbon and nitrogen cycles involved in microorganisms were damaged. Furthermore, the decreased diversity of rhizosphere soil microorganisms and the increased abundance of pathogenic fungi contribute to the continuous cropping obstacles of tobacco.

Soil supports life by serving as a living, breathing fabric that connects the atmosphere to the Earth's crust. The study of soil science and pedology, or the study of soil in the natural environment, spans scales, disciplines, and societies worldwide. Soil science continues to grow and evolve as a field given advancements in analytical tools, capabilities, and a growing emphasis on integrating research across disciplines. A pressing need exists to more strongly incorporate the study of soil, and soil scientists, into research networks, initiatives, and collaborations. This review presents three research areas focused on questions of central interest to scientists, students, and government agencies alike: 1) How do the properties of soil influence the selection of habitat and survival by organisms, especially threatened and endangered species struggling in the face of climate change and habitat loss during the Anthropocene? 2) How do we disentangle the heterogeneity of abiotic and biotic processes that transform minerals and release life-supporting nutrients to soil, especially at the nano-to microscale where mineral-water-microbe interactions occur? and 3) How can soil science advance the search for life and habitable environments on Mars and beyond-from distinguishing biosignatures to better utilizing terrestrial analogs on Earth for planetary exploration? This review also highlights the tools, resources, and expertise that soil scientists bring to interdisciplinary teams focused on questions centered belowground, whether the research areas involve conservation organizations, industry, the classroom, or government agencies working to resolve global chal-lenges and sustain a future for all.

Arctic and boreal permafrost soil organic carbon (SOC) decomposition has been slower than carbon inputs from plant growth since the last glaciation. Anthropogenic climate warming has threatened this historical trend by accelerating SOC decomposition and altering wildfire regimes. We accurately modeled observed plant biomass and carbon emissions from wildfires in Alaskan ecosystems under current climate conditions. In projections to 2300 under the RCP8.5 climate scenario, we found that warming and increased atmospheric CO2 will result in plant biomass gains and higher litterfall. However, increased carbon losses from (a) wildfire combustion and (b) rapid SOC decomposition driven by increased deciduous litter production, root exudation, and active layer depth will lead to about 4.4 PgC of soil carbon losses from Alaska by 2300 and most (88%) of these loses will be from the top 1 m of soil. These SOC losses offset plant carbon gains, causing the ecosystem to transition to a net carbon source after 2200. Simulations excluding wildfire increases yielded about a factor of four lower SOC losses by 2300. Our results show that projected wildfire and its direct and indirect effects on plant and soil carbon may accelerate high-latitude soil carbon losses, resulting in a positive feedback to climate change.

Recent changes in species composition, and increases in shrub abundance in particular, have been reported as a result of warming in Arctic tundra. Despite these changes, the driving factors that control shrubification and its future trajectory remain uncertain. Here we used an ecosystem model, ecosys, to mechanistically represent the processes controlling recent and 21st century changes in plant functional type using RCP8.5 climate forcing across North American Arctic tundra. Recent and projected warming was modeled to deepen the active layer (spatially averaged by similar to 0.35m by 2100) and thereby increase nutrient availability. Shrub productivity was modeled to increase across much of the tundra, particularly in Alaska and tundra-boreal ecotones. Deciduous and evergreen shrubs increased from similar to 45% of total tundra ecosystem net primary productivity (NPP) in recent decades to similar to 70% by 2100. The increased canopy cover of shrubs reduced incoming shortwave radiation for low-lying plants, causing declines in graminoids NPP from a current 35% of tundra NPP to 18%, and declines in nonvascular plants from 20% to 12%. The faster-growing deciduous shrubs modeled with less efficient nutrient conservation dominated much of the low Arctic by 2100 where nutrient cycling became more rapid, while the slower-growing evergreen shrubs modeled with more efficient nutrient conservation dominated a wider latitudinal range that extended to the high Arctic where nutrient cycling remained slower. We conclude that high-latitude vegetation dynamics over the 21st century will depend strongly on soil nutrient dynamics, diversity in plant traits controlling nutrient uptake and conservation, and light competition.