Long-Term Atmospheric Nitrogen Deposition Enhances Forest Production by Suppressing Microbial Competition for Phosphorus.

Ecological stoichiometry theory predicts that prolonged nitrogen (N) deposition exacerbates phosphorus (P) limitation in terrestrial primary production. However, this hypothesis remains untested using canopy N addition (CN) experiments that consider critical canopy processes. In a 10-year CN and understory N addition (UN) experiment in P limited subtropical forests, CN unexpectedly increased plant biomass and P uptake while reducing soil microbial P, alleviating plant P limitation.

Edaphic and climatic factors control the response of nutrient-cycling enzyme activity to common heavy metals in soils.

Soil enzymes, which are crucial catalysts in soil nutrient cycling, are sensitive to heavy metals and metalloids (HMMs). Yet, the mechanistic understanding of soil enzyme activities (EAs) response to HMMs is still only rudimentarily known. By analyzing 1989 paired observations from 145 studies investigating HMMs effect on 14 enzymes, we found that HMMs decreased the activity of β-D-glucosidase (-25.

Towards a Mechanistic Understanding of Legume Functioning in Natural Restoration of Degraded Ecosystem: Legume-Specific Impacts on Nitrogen Transformation Processes.

Legumes have important functions in degraded ecosystems as they can mediate atmospheric nitrogen (N) inputs and increase soil N availability. However, it remains unclear whether legumes affect N availability only through biological N fixation or stimulating microbial N transformations. In this study, nine native legumes and four non-legumes were collected following a 9-year natural vegetation restoration experiment in a karst rocky desertification area.

Cadmium inhibits carbon and nitrogen cycling through soil microbial biomass and reduces soil nitrogen availability.

Microbial mediated carbon and nitrogen cycling response to cadmium are often observed in soil; however, a unified framework of this response has not yet been established. By analyzing 1232 observations from 166 publications, we found that cadmium decreased microbial biomass carbon (-16 %) and nitrogen (-21 %), dissolved organic nitrogen (-27 %), nitrification rate (-17 %), microbial respiration rate (-12 %), and β-1,4-glucosidase (-21 %) and urease (-16 %) activities, but increased microbial metabolic quotient (+11 %) and fungal-to-bacterial ratio (+39 %). The cadmium impact was concentration-dependent, becoming more pronounced at higher concentrations.

Edaphic factors mediate the response of nitrogen cycling and related enzymatic activities and functional genes to heavy metals: A review.

Soil nitrogen (N) transformations control N availability and plant production and pose environmental concerns when N is lost, raising issues such as soil acidification, water contamination, and climate change. Former studies suggested that soil N cycling is chiefly regulated by microbial activity; however, emerging evidence indicates that this regulation is disrupted by heavy metal (HM) contamination, which alters microbial communities and enzyme functions critical to N transformations. Environmental factors like soil organic carbon, soil texture, water content, temperature, soil pH, N fertilization, and redox status play significant roles in modulating the response of soil N cycling to HM contamination.

Enhancing soybean germination and vigor under water stress: the efficacy of bio-priming with sodium carboxymethyl cellulose and gum arabic.

Seed priming can significantly enhance the tolerance of soybean against different environmental stresses by improving seed water uptake and modulating stress-response mechanisms. In particular, seed priming with sodium carboxymethylcellulose (SCMC) and gum Arabic (GA) can support seeds to withstand extreme conditions better, promoting more consistent germination and robust seedling establishment, which is crucial for achieving stable agricultural yields. The present study investigated the effects of seed priming using a combination of SCMC and GA (10% CG) on the germination, growth, and biochemical responses of six soybean varieties under drought and flooding stress conditions.

Influence of drought stress on phosphorus dynamics and maize growth in tropical ecosystems.

Drought has a significant impact on ecosystem functions, especially on the biogeochemical cycling of phosphorus (P), which is a crucial nutrient for plant growth and productivity. Despite its importance, the effects of different drought scenarios on soil P cycling and availability remain poorly understood in previous studies. This study simulated drought conditions in tropical soils using maize as a test crop under varying field capacity (FC) levels (100%, 80%, 60%, 40%, and 20%) over a 60-day pot experiment.

Fire Reduces Soil Nitrate Retention While Increasing Soil Nitrogen Production and Loss Globally.

Elucidating the response of soil gross nitrogen (N) transformations to fires could improve our understanding of how fire affects N availability and loss. Yet, how internal soil gross N transformation rates respond to fires remains unexplored globally. Here, we investigate the general response of gross soil N transformations to fire and its consequences for N availability and loss.

Ecological impacts and management strategies of pesticide pollution on aquatic life and human beings.

Pesticide contamination has become a global concern. Pesticides can sorb onto suspended particles and deposit into the sedimentary layers of aquatic environments, resulting in ecosystem degradation, pollution, and diseases. Pesticides impact the behavior of aquatic environments by contaminating organic matter in water, which serves as the primary food source for aquatic food webs.

Soil recalcitrant but not labile organic nitrogen mineralization contributes to microbial nitrogen immobilization and plant nitrogen uptake.

Soil organic nitrogen (N) mineralization not only supports ecosystem productivity but also weakens carbon and N accumulation in soils. Recalcitrant (mainly mineral-associated organic matter) and labile (mainly particulate organic matter) organic materials differ dramatically in nature. Yet, the patterns and drivers of recalcitrant (M) and labile (M) organic N mineralization rates and their consequences on ecosystem N retention are still unclear.

Warming-Induced Stimulation of Soil NO Emissions Counteracted by Elevated CO from Nine-Year Agroecosystem Temperature and Free Air Carbon Dioxide Enrichment.

Globally, agricultural soils account for approximately one-third of anthropogenic emissions of the potent greenhouse gas and stratospheric ozone-depleting substance nitrous oxide (NO). Emissions of NO from agricultural soils are affected by a number of global change factors, such as elevated air temperatures and elevated atmospheric carbon dioxide (CO). Yet, a mechanistic understanding of how these climatic factors affect NO emissions in agricultural soils remains largely unresolved.

Climate controls on nitrate dynamics and gross nitrogen cycling response to nitrogen deposition in global forest soils.

Understanding the patterns and controls regulating nitrogen (N) transformation and its response to N enrichment is critical to re-evaluating soil N limitation or availability and its environmental consequences. Nevertheless, how climatic conditions affect nitrate dynamics and the response of gross N cycling rates to N enrichment in forest soils is still only rudimentarily known. Through collecting and analyzing 4426-single and 769-paired observations from 231 N labeling studies, we found that nitrification capacity [the ratio of gross autotrophic nitrification (GAN) to gross N mineralization (GNM)] was significantly lower in tropical/subtropical (19%) than in temperate (68%) forest soils, mainly due to the higher GNM and lower GAN in tropical/subtropical regions resulting from low C/N ratio and high precipitation, respectively.

Initial evidence on the effect of copper on global cropland nitrogen cycling: A meta-analysis.

Copper (Cu) is a key cofactor in ammonia monooxygenase functioning responsible for the first step of nitrification, but its excess availability impairs soil microbial functions and plant growth. Yet, the impact of Cu on nitrogen (N) cycling and process-related variables in cropland soils remains unexplored globally. Through a meta-analysis of 1209-paired and 319-single observations from 94 publications, we found that Cu (Cu addition or Cu-polluted soil) reduced soil potential nitrification by 33.

Land Use Change from Natural Tropical Forests to Managed Ecosystems Reduces Gross Nitrogen Production Rates and Increases the Soil Microbial Nitrogen Limitation.

Understanding the underlying mechanisms of soil microbial nitrogen (N) utilization under land use change is critical to evaluating soil N availability or limitation and its environmental consequences. A combination of soil gross N production and ecoenzymatic stoichiometry provides a promising avenue for nutrient limitation assessment in soil microbial metabolism. Gross N production via N tracing and ecoenzymatic stoichiometry through the vector and threshold element ratio (Vector-TER) model were quantified to evaluate the soil microbial N limitation in response to land use changes.

Aridity creates global thresholds in soil nitrogen retention and availability.

Identifying tipping points in the relationship between aridity and gross nitrogen (N) cycling rates could show critical vulnerabilities of terrestrial ecosystems to climate change. Yet, the global pattern of gross N cycling response to aridity across terrestrial ecosystems remains unknown. Here, we collected 14,144 observations from 451 N-labeled studies and used segmented regression to identify the global threshold responses of soil gross N cycling rates and soil process-related variables to aridity index (AI), which decreases as aridity increases.

Topography-driven differences in soil N transformation constrain N availability in karst ecosystems.

Fragile karst ecosystems are characterized by complex topographic landscapes associated with high variations in vegetation restoration. Identifying the characteristics and driving factors of nitrogen (N) availability across the topographic gradient is essential to guide vegetation restoration in karst regions. In this study, we collected soil samples and plant leaves along the topographic gradient (ridge, upper slope, middle slope, and foot slope) of convex slopes in the karst fault basin of southwest China, and determined the indicators reflecting soil N availability, N transformation rates, and their controlling factors.

Spatial prediction of lime requirements by adjusting aluminium saturation in Sub-Saharan Africa croplands.

Acidic soils cover over 30 % of Sub-Saharan Africa cropland. Acidic soils deprive crops of calcium, magnesium, potassium, molybdenum, and phosphorus due to aluminium (Al), manganese, and iron toxicities. Thus, liming is required to adjust the level of exchangeable Al to the desired level of Al saturation of the crops grown.

Exploring the Influence of Chemical Conditions on Nanoparticle Graphene Oxide Adsorption onto Clay Minerals.

High concentrations of graphene oxide (GO), a nanoparticle substance with rapid manufacturing development, have the ability to penetrate the soil surface down to the mineral-rich subsurface layers. The destiny and distribution of such an unusual sort of nanomaterial in the environment must therefore be fully understood. However, the way the chemistry of solutions impacts GO nanoparticle adsorption on clay minerals is still unclear.

Carbon and nitrogen fractions control soil NO emissions and related functional genes under land-use change in the tropics.

Converting natural forests to managed ecosystems generally increases soil nitrous oxide (NO) emission. However, the pattern and underlying mechanisms of NO emissions after converting tropical forests to managed plantations remain elusive. Hence, a laboratory incubation study was investigated to determine soil NO emissions of four land uses including forest, eucalyptus, rubber, and paddy field plantations in a tropical region of China.

Global patterns and controls of yield and nitrogen use efficiency in rice.

Factors influencing rice (Oryza sativa L.) yield mainly include nitrogen (N) fertilizer, climate and soil properties. However, a comprehensive analysis of the role of climatic factors and soil physical and chemical properties and their interactions in controlling global yield and nitrogen use efficiency (e.