Effects of nitrogen and phosphorus additions on soil microbial community structure and ecological processes in the farmland of Chinese Loess Plateau

Microorganisms regulate the responses of terrestrial ecosystems to anthropogenic nutrient inputs.The escalation of anthropogenic activities has resulted in a rise in the primary terrestrial constraining elements,namely nitrogen(N)and phosphorus(P).Nevertheless,the specific mechanisms governing the influence of soil microbial community structure and ecological processes in ecologically vulnerable and delicate semi-arid loess agroecosystems remain inadequately understood.Therefore,we explored the effects of different N and P additions on soil microbial community structure and its associated ecological processes in the farmland of Chinese Loess Plateau based on a 36-a long-term experiment.Nine fertilization treatments with complete interactions of high,medium,and low N and P gradients were set up.Soil physical and chemical properties,along with the microbial community structure were measured in this study.Additionally,relevant ecological processes such as microbial biomass,respiration,N mineralization,and enzyme activity were quantified.To elucidate the relationships between these variables,we examined correlation-mediated processes using statistical techniques,including redundancy analysis(RDA)and structural equation modeling(SEM).The results showed that the addition of N alone had a detrimental effect on soil microbial biomass,mineralized N accumulation,andβ-1,4-glucosidase activity.Conversely,the addition of P exhibited an opposing effect,leading to positive influences on these soil parameters.The interactive addition of N and P significantly changed the microbial community structure,increasing microbial activity(microbial biomass and soil respiration),but decreasing the accumulation of mineralized N.Among them,N24P12 treatment showed the greatest increase in the soil nutrient content and respiration.N12P12 treatment increased the overall enzyme activity and total phospholipid fatty acid(PLFA)content by 70.93%.N and P nutrient contents of the soil dominate the microbial community structure and the corresponding changes in hydrolytic enzymes.Soil microbial biomass,respiration,and overall enzyme activity are driven by mineralized N.Our study provides a theoretical basis for exploring energy conversion processes of soil microbial community and environmental sustainability under long-term N and P additions in semi-arid loess areas.

Effects of FeNi-phosphorus-carbon system on crystal growth of diamond under high pressure and high temperature conditions

This paper reports the crystal growth of diamond from the Fe Ni–Carbon system with additive phosphorus at high pressures and high temperatures of 5.4–5.8 GPa and 1280–1360°C. Attributed to the presence of additive phosphorus,the pressure and temperature condition, morphology, and color of diamond crystals change obviously. The pressure and temperature condition of diamond growth increases evidently with the increase of additive phosphorus content and results in the moving up of the V-shape region. The surfaces of the diamonds also become coarse as the additive phosphorus added in the growth system. Raman spectra indicate that diamonds grown from the Fe Ni-phosphorus-carbon system have more crystal defects and impurities. This work provides a new way to enrich the doping of diamond and improve the experimental exploration for future material applications.

Analysis Methods for the Determination of Anthropogenic Additions of P to Agricultural Soils

Phosphorus loading and measurement is of concern on lands where biosolids have been applied. Traditional soil testing for plant-available P may be inadequate for the accurate assessment of P loadings in a regulatory environment as the reported levels may not correlate well with environmental risk. In order to accurately assess potential P runoff and leaching, as well as plant uptake, we must be able to measure organic P mineralized by the biotic community in the soil. Soils with varying rates of biosolid application were evaluated for mineralized organic P during a 112-day incubation using the difference between P measured using a rapid-flow analyzer (RFA) and an axial flow Varian ICP-OES. An increase in the P mineralized from the treated soils was observed from analysis with the Varian ICP-OES, but not with the RFA. These results confirm that even though organic P concentrations have increased due to increasing biosolid application, traditional soil testing using an RFA for detection, would not accurately portray P concentration and potential P loading from treated soils.

Tribological behavior of black phosphorus nanosheets as water-based lubrication additives

Black phosphorus(BP)with a layered structure has been used gradually as a lubrication additive in the tribological area.In this study,BP powders are produced via an easy method of high-energy ball milling using red phosphorus as a raw material.Subsequently,BP nanosheets are prepared via liquid exfoliation in N-methyl pyrolidone solvent.The tribological behavior of BP nanosheets as water-based lubrication additives(BP-WL)is evaluated under Ti6Al4V(TC4)/GCr15 contact.The results suggest that the 70 mg/L BP-WL sample exhibits excellent lubrication performance,whose coefficient of friction(COF)and ball wear rate reduced by 32.4%and 61.1%,respectively,compared with those of pure water.However,as the load increased,the tribological properties of BP-WL reduced gradually because of the agglomeration of BP nanosheets.Based on tribological experiments and worn surface analysis,boundary lubrication mechanisms are proposed.The friction reduced,which is primarily attributed to the low interlaminar shear and adsorption of BP nanosheets.In addition,a tribochemical reaction film comprising TiO_(2),Al_(2)O_(3),and Fe_(2)O_(3)effectively protects the surface of titanium alloy/steel from wear.This new water-based lubrication additive can be used to process titanium alloys.

Effects of nitrogen and phosphorus additions on soil nematode community of soybean farmland

The nitrogen(N)and phosphorus(P)addition promotes the abundance of soybean soil nematodes.The addition of nitrogen can alleviate the suppression of phosphorus on nematodes.Phosphorus addition affects nematode abundance by ammonium nitrogen.

Black phosphorus quantum dots: A new-type of water-based high-efficiency lubricant additive

Black phosphorus quantum dots(BPQDs),obtained via a typical solution-based top-down method,were used as water-based lubricant additives.BPQDs exhibited remarkable friction reduction and anti-wear properties even at the ultra-low concentration of 0.005 wt%,which reduced the friction coefficient and wear volume of the base liquid by 32.3%and 56.4%,respectively.In addition,the load-supporting capacity of the base liquid increased from 120 N to over 300 N.BPQDs-based additives exhibited a relatively long lifetime at a relatively high load of 80 N.The performance of BPQDs considerably exceeded that of the BP;this may be attributed to their small and uniform particle size,good dispersion stability in water,and high reactivity at the frictional surfaces.The results of the surface wear resistance analysis demonstrated that a robust tribochemical film with a thickness of approximately 90 nm was formed on the rubbing surface lubricated with 0.005 wt%of BPQDs dispersion.Moreover,the film served as a direct evidence of the excellent tribological performance of BPQDs.

Effect of annealing time and phosphorus addition on bake hardening behavior of ultra-low carbon bake hardening steel

The relationship of the P and C grain boundary segregation and its effect on bake hardening behavior were investigated in ultra-low carbon bake hardening (ULC-BH)steel with and without P addition annealed at 810 ℃ for various time using electron probe micro-analyzer,electroh backscattered diffraction,and three-dimensional atomic probe techniques.Results revealed that P addition and annealing duration considerably affected the bake hardening behavior of experimental steel. The BH value of ULC-BH steel without P addition is lower than that with P addition within a short annealing time,and the difference in the BH value gradually decreases as the annealing duration is prolonged.P segregation is dominant in terms of a high P bulk content in steels with P addition at the expense of C segregation during annealing.By contrast,opposite effects are observed in low carbon bake hardening steel.The high residual solute C content in steel with P addition is due to P segregation at the grain boundary.Site competition is mainly responsible for the lower BH value in ULC-BH steel without P addition than that with P addition.As the annealing time is further extended,C segregation begins at grain boundary despite the delayed P segregation,leading to a gradual decrease in the solute concentration in the matrix of steels with P addition.C and P segregations reach the equilibrium as the annealing time increases to 60 min at 810 ℃ in the two steel samples.Theoretical calculations reveal that the residual solute C concentration in the matrix decreases to zero,and this finding is consistent with the change trend of the bake hardening value.Hence,the C segregation at grain boundary. adversely influences the bake hardening property of ULC-BH steel.

Divergent responses of plant biomass and diversity to short-term nitrogen and phosphorus addition in three types of steppe in Inner Mongolia,China

Background:Understanding the response of the plant community to increasing nitrogen(N)and phosphorus(P)inputs is helpful for managing and protecting grassland ecosystems in semiarid areas.However,information about different types of steppe responses to N and P availability in semiarid grasslands is limited.In 2017-2018,two field experiments were conducted with six levels of N(from 5 to 30 g N m^(−2)yr^(−1))and P(from 2.5 g to 15 g P m^(−2)yr^(−1))additions in three different temperate steppes,including meadow steppe(MS),typical steppe(TS),and desert steppe(DS),in northern China to study the effects of these addition rates on community biomass and diversity.Results:Our results showed that plant biomass and diversity in the three steppe types in Inner Mongolia responded differently to elevated N and P inputs.Increasing P promoted aboveground and belowground biomass more than increasing N in the three temperate steppes.Short-term N and P additions reduced plant diversity to some extent,with the most pronounced decreases in MS and DS.It is noteworthy that there were response thresholds for plant diversity and biomass in response to N and P inputs in different steppe types(e.g.,10 g P m^(−2)yr^(−1)).Furthermore,redundancy analysis and stepwise regression analysis revealed that changes in soil properties induced by nutrient addition and climate conditions jointly regulated changes in vegetation biomass and diversity.Conclusions:The plant biomass and diversity of three steppe types in Inner Mongolia respond divergently to elevated N and P inputs.Our results indicate that regional differences in climate and soil substrate conditions may jointly contribute to the divergent responses of plant biomass and diversity to short-term N and P addition.Our analyses provide new insights into managing and protecting grassland ecosystems.Considering that the effects of nutrient addition on plant diversity and productivity may have increasing effects over time,studies on long-term in situ nutrient addition are necessary.

A brief review of tribological properties for black phosphorus

Black phosphorus (BP) is a new class of two-dimensional (2D) layered material, which shows the unanticipated characteristics in many aspects including electronics, transistors, sensors, energy storage, batteries, photocatalysis, and other applications due to its high charge carrier mobility, tunable direct bandgap, and unique in-plane anisotropic structure. In addition, BP has drawn tremendous attention in the field of tribology due to the low shear strength, the layered structure, and the weak connected force between the layers by van der Waals interaction. In recent years, many significant progresses have been made in experimental studies on BP materials as solid lubricants or lubrication additives. This work offers a review of researching regarding the tribological properties of BP. Moreover, the lubrication mechanisms of BP as the lubrication additive including the formation of the tribo-film, micro-bearing effect, and self-repair performance are also summarized. Finally, the current challenges and prospects of BP material as lubricant are proposed.

Black phosphorus as a new lubricant

In recent years, a new 2D-layered material—black phosphorus(BP)—has been a rising star after the era of graphene owing to its high charge carrier mobility, tunable direct bandgap and unique in-plane anisotropic structure. With the development of the synthesis and modification methods of BP, its extensive applications, e.g., transistors, batteries and optoelectronics have emerged. In order to explore its full potential, research into the tribological properties of BP 2D-layered materials such as lubrication additives and fillers in self-lubricating composite materials would be not only of high scientific value but also of practical significance. In this work, recent advances on the friction and lubrication properties of BP nanosheets made by our group, including the micro-friction properties, the lubrication properties of BP nanosheets as water-based and oil-based lubrication additives, and the friction and wear of BP/PVDF composites will be presented. Finally, the future challenges and opportunities in the use of BP materials as lubricants will be discussed.

Short-term microbial responses to soluble inorganic P input in a tropical lowland rain forest in Amazonia

In non-flooded lowland rain forests with low soil phosphorus(P)in parts of Amazonia,P cycling largely occurs via leaf litter recycling by arbuscular mycorrhizal(AM)fungal symbionts.Occasional high input of P into these ecosystems occurs during drought years with increased litterfall.As the length and frequency of drought events are projected to increase in the region,a single-dose nutrient addition experiment was carried out to test how this would impact P cycling.An application rate of 4 kg P ha^(-1) was used,which corresponds to twice the amount of litter-derived P in an average year.It was hypothesized that i)the added mineral P would be immobilized by soil microorganisms,leading to measurable increase in soil microbial biomass carbon(C)and P and ii)AM colonization rate would be reduced by the pulse in mineral P available for plant uptake.The results did not support either of our hypotheses.The addition of P did not have an effect on AM root colonization,nor was P immobilized by soil microbiota during the experimental period.The lack of a difference between the control and treatment at our study site could be attributed to the relatively low one-off dose of P applied that did not change either the colonization rate of roots by AM fungi or the amount of soil available labile P.To obtain a mechanistic understanding of the availability,capture,and use of P by plant-symbiont associations in tropical rain forest ecosystems,further integrated studies of the soil-plant system combining long-term nutrient manipulations,modeling,and experimental approaches are required.

Analysis of dispersion in the nano-InP doped fiber

We propose that nanomaterials are used for fibers.A novel nano-InP doped fiber has been fabricated by the method of modified chemical vapor deposition(MCVD).It has been measured that the doping concentration of phosphorus element is 0.1%.The relationship between refractive index and the wavelength is obtained by fitting experimental data to Sellmeier equation.Dispersion of the fiber has been calculated in the wavelength range of 1.2-1.6 μm.As the wavelength varies from 1.20 μm to 1.60 μm,dispersion paramete...

Survival and growth of dominant tree seedlings in seasonally tropical dry forests of Yucatan: site and fertilization effects

Aims Seasonally tropical dry forests of the Yucatan Peninsula are typically found in sites with nutrient-poor soils because of the recent geologi-cal origin of the region.The landscape is dominated by extensive karstic plates that shape environments where vegetation regenera-tion through seed germination may be limited by the availability of suitable microsites.In this study,we documented the survival and growth of seedlings from three dominant tree species(Bursera simaruba,Piscidia piscipula and Lysiloma latisiliquum)in seasonally tropical dry forests in Yucatan.Specifically,we evaluated the effect of nutrient addition(N and P,separately and in combination)on seedling survival and growth across three sites with differing levels of precipitation.Methods We conducted a nutrient addition experiment,whereby we estab-lished 12 plots of dimensions 10×10 m(100 m^(2))at each site,from which three plots were randomly selected to receive one of four treatments:N addition,P addition,N and P addition and no nutri-ent addition(controls).Prior to treatment application,in each plot,we planted 10 seedlings of each species in October 2010 and sub-sequently conducted surveys of plant growth and survival every 20 days from November 2010 to April 2011.Important Findings Overall,nutrient addition increased seedling survival and the mag-nitude of this effect was similar among sites.We did not observe an additive effect of the N+P treatment on survival.Similarly,we observed a positive effect of nutrient addition on seedling growth,but this effect was contingent upon site;regarding survival,the effects of N and P on seedling growth were not additive.These results suggest that seedling recruitment and growth in the three dominant species of trees in Yucatan are limited by nutrient avail-ability but that the magnitude of this effect,particularly on seedling growth,is specific for species and site.