Movement Of Nitrogen Research Articles

Poly-γ-glutamic production by solid-state fermentation of Bacillus natto in ammonia nitrogen movement and soil water retention processes

A high polyglutamic acid (γ-PGA) producing strain of Bacillus natto UV-40–50 was screened by ultraviolet mutagenesis treatment and identified as still belonging to the Bacillus specie. The optimal fermentation medium composition for solid state fermentation (SSF) of B. natto strain UV-40–50 strain was determined by one-way analysis of variance, under which the yield of γ-PGA was 55.19 g/kg, and the presence and molecular weight of γ-PGA in the γ-PGA-purified samples were determined by a series of characterizations. The purification ability of the unseparated solid fermentation product (SFP) on ammonia nitrogen and nitrite in the water column, as well as its effect on soil water retention, germination rate and seedling length of lettuce and cabbage were further investigated. The results showed that the addition of 1 g/m3 SFP could effectively remove more than 60 % of ammonia nitrogen and more than 40 % of nitrite in the water body; the addition of 0.01 % SFP could increase the water retention capacity of cabbage soil by 2.13 times, and increase the water retention capacity of lettuce soil by 12 %; at the same time, the SFP could also significantly increase the germination rate and seedling length of both cabbage and lettuce.

SENTINEL-2, HERRAMIENTA EN LA SEGURIDAD AGROALIMENTARIA Y AGRICULTURA DE PRECISIÓN

<p><strong>Background</strong>. Food production as the world population increases is an issue of global importance, resulting in uncertainty around agri-food security (AS). It is essential to apply new technology that monitors and makes crop management more efficient to achieve sustainable development (SD). One technology responsible for improving conventional farmers' practices is precision agriculture (PA) using tools such as big data analytics, artificial intelligence and geospatial analysis. In this sense, the monitoring of markers through satellite images requires knowledge for adequate interpretations. Some satellites have multispectral images, monitoring with these has demonstrated high precision in predicting crop yields. There are several satellites, Landsat 8 (L8) and Sentinel-2 (S2) are the most advanced and open access. <strong>Objective</strong>. To present the spectrophotometric fundamentals and current state of remote sensing with S2 multispectral images in relation to problems facing agriculture. It is concluded that remote sensing is a tool that contributes to the proper management of agricultural production, showing high reliability. <strong>Methodology</strong>. This review was carried out in accordance with the PRISMA statement (Preferred Reporting Items for Systematic reviews and Meta-Analyses), a systematic analysis of literature in the databases was carried out. MDPI, Springer Link, Science Direct, Taylor and Francis and Google Scholar were consulted. The key words were “Sentinel-2, R2, Salinity, Pest, Nitrogen, Drought”. Zotero (www.zotero.org) was used as a free access bibliography manager; articles that were not related to the research objectives were excluded. <strong>Results</strong>. Articles related to the objective of this review were identified in the databases; the study was structured based on the needs of precision agriculture (PA). The importance of adequately managing the water demand of crops, salinity stress, pest detection and the movement of nitrogen (N) in the soil-plant-atmosphere interaction. <strong>Implications</strong>. Remote perception of phenomena at the field level represents an area for improvement in crop management. Increasing resource efficiency is crucial to achieving agri-food security (AS) and thus part of the sustainable development goals (SDGs). <strong>Conclusion</strong>. The S2 has multispectral images that, when processed, allow obtaining information about the crop, i.e. monitoring stress, humidity in plants and optimization of plant nutrition. With PA, decisions are made for crop management, costs are reduced by reducing losses due to crop stress, and resource efficiency increases.<strong> </strong></p>

Modelling and optimization of urea super granule (USG) placement depth in paddy cultivation under check basin irrigation using HYDRUS-2D model

Urea, a nitrogenous fertilizer which plays an important role in enhancing yield, but has a drawback of low nitrogen use efficiency (NUE). Use of urea super granule (USG) and coated urea have advantages over prilled urea in terms of higher NUE and eventually improved yield. Depth of placement (DOP) of USG plays a major role in achieving higher NUE and yield. However, appropriate depth of placement needs detailed knowledge about water and nitrogen (N) movements to provide maximum nutrient to plants. Therefore, an experiment was conducted in the paddy field using USG coated with three different types of coating (USG with nano bentonite and neem oil (T1), USG with heated nano bentonite and neem oil (T2) and USG with sulfer and acacia gum solution (T3)) and placed at the centre of four hills of paddy as basal dose at ICAR-IARI, New Delhi. Spatial and temporal data of soil moisture and Nwere collected for the initial 32 days in paddy field after crops establishment. The HYDRUS-2D model was calibrated and validated using the observed data. Calibrated model was used for simulation of N movement in different soil types and for different depths of USG placement. Results revealed that permissible soil like sandy loam, the optimum DOP irrespective of coating was 5 cm. For sandy clay loam soil, optimum depth of placement was found to be 10 cm, 6 cm and 10 cm for T1, T2 and T3 type of coatings. Similarly, for clay loam soil, depth of USG placement for T1, T2 and T3 type coating was found to be 8 cm, 10 cm and 8 cm, respectively. Using the optimum DOP in sandy clay loam soil, results showed that both i.e., DOP and coating type has significant effect on number of tillers m−2 and yield (t ha−1). In 2020 and 2021, the highest number of tillers per square meter at 30 days after transplanting (DAT) was observed in the T3 treatment at DOP of 10 cm, with counts of 453.66 and 454.88, respectively. Following closely were T2 at DOP of 10 cm (447.33 and 119.55) and T1 at DOP of 6 cm (443.44 and 444.77). Similarly, the best yield in 2020 and 2021 were observed from T3 treatment at DOP of 10 cm (5.41 t/ha and 5.44 t/ha), followed by T2 at DOP of 10 cm (5.33 t/ha and 5.42 t/ha), and T1 at DOP of 6 cm (5.29 t/ha and 5.31 t/ha). This study may assist the farmers, researchers, manufacturers and policy makers to make selection of the optimum depth of placement for higher NUE and yield in different soil types.

Comparison of sediment and water column nutrient processing rates in agricultural streams of contrasting buffer land use

AbstractWatershed nutrient management often focuses on actions that reduce the movement of nitrogen (N) and phosphorus (P) from agricultural lands into streams. One area of management focus is the buffer of land adjacent to streams. Wetlands and forests in this buffer can intercept and retain N and P from the landscape. In addition to directly intercepting agricultural nutrients, natural habitats in the buffer can alter stream geomorphology and influence the in‐stream processing and transformation of N and P to less labile and mobile forms. Here, we assess the influence of buffer land cover on in‐stream processing of N and P. We measured nutrient dynamics in the water column and sediments of agricultural streams in the Fox River and Duck Creek watersheds (WI, USA) during the growing season. In these streams, water column processing was low, possibly due to a lack of primary producers in the water column. Water column P processing was weakly associated with wetland land cover in the buffer, but buffer land cover had no clear effect on inorganic N processing. On the other hand, sediments were almost always a source of inorganic P and a sink for inorganic N. Sediment P release was higher in streams with more agricultural land cover in the buffer. Sediments in streams with agricultural land cover in the buffer also removed more nitrate, even after accounting for the greater availability of nitrate in those streams. The buffer land cover conditions we quantified occupy a very small portion of the overall watershed (100 m wide, for 1 km upstream of the study site) but nevertheless appear to influence in‐stream cycling of N and P. For P management, reducing agricultural land cover in buffers is already a priority due to the ability of wetlands and forests to intercept nutrients, but this study suggests there may be some additional benefit due to changes in in‐stream P processing.

A novel method for tracking nitrogen kinetics in vivo under hyperbaric conditions using radioactive nitrogen-13 gas and positron emission tomography.

Decompression sickness (DCS) is caused by gaseous nitrogen dissolved in tissues forming bubbles during decompression. To date, no method exists to identify nitrogen within tissues, but with advances in positron-emission tomography (PET) technology, it may be possible to track gaseous radionuclides into tissues. We aimed to develop a method to track nitrogen movement in vivo and under hyperbaric pressure that could then be used to further our understanding of DCS using nitrogen-13 (13N2). A single anesthetized female Sprague-Dawley rat was exposed to 625 kPa, composed of air, isoflurane, and 13N2 for 10 min. The PET scanner recorded 13N2 during the hyperbaric exposure with energy windows of 250-750 keV. The PET showed an increase in 13N2 concentration in the lung, heart, and abdominal regions, which all reached a plateau after ∼4 min. This showed that it is possible to gain noninvasive in vivo measurements of nitrogen kinetics through the body while at hyperbaric pressures. Tissue samples showed radioactivity above background levels in the blood, brain, liver, femur, and thigh muscle when assessed using a γ counter. The method can be used to evaluate an array of challenges to our understanding of decompression physiology by quantifying nitrogen load through γ counts of 13N2, and signal intensity of the PET. Further development of the method will improve the specificity of the measured outcomes, and enable it to be used with larger mammals, including humans.NEW & NOTEWORTHY This article describes a method for the in vivo quantification and tracking of nitrogen through the mammalian body whilst exposed to hyperbaric pressure. The method has the potential to further our understanding of decompression sickness, and quantitatively evaluate the effectiveness of both the treatment and prevention of decompression sickness.

Nitrogen Loss and Migration in Rice Fields under Different Water and Fertilizer Modes.

Irrigating aquaculture wastewater in appropriate irrigation and drainage modes in paddy fields could reduce water and fertilizer loss. However, the precise mechanisms involved in the degradation and movement of nitrogen in various water and fertilizer modes are still not fully understood. This study involves conducting a controlled experiment using barrels to examine the effects of various water quality, irrigation and drainage methods, and fertilization levels. The aim is to analyze the patterns of nitrogen degradation, loss, migration, and absorption in surface water, underground drainage, and soil leakage at different depths. The results showed the following: (1) The paddy field has a significant purification effect on aquaculture wastewater after one day of irrigation, reached at 78.55-96.06%. (2) Aquaculture wastewater irrigation increased nitrogen concentration in the plough layer, which helps rice roots absorb nitrogen and boosts plant TN. (3) In special dry years, underground seepage is the predominant method of nitrogen loss, and underground drainage nitrogen concentration peaks 2-6 days after fertilization. (4) Under aquaculture wastewater irrigation, the TN loss load of II decreased by 27.65-42.45% than FSI. Compared with IA-80, the TN degradation rate of IA in surface water increased by 18.51%, TN loss load decreased by 5.48%, TN absorption rate significantly increased by 14.61%, and yield increased by 31.14% significantly. IA is recommended in special dry years, which can improve the TN absorption rate and ensure high yield while significantly reducing the loss load of nitrogen. The findings can provide a basis for the purification of aquaculture wastewater through paddy field ecosystems in response to fertilizer supply levels.

Nitrogen Dynamics in Soil Treated with Plant-Growth Promoting Bacteria and Urea Fertilizer

The mineralization of urea fertilizer significantly impacts nitrogen movement in the soil. An incubation study was done on a lab scale basis to examine nitrogen dynamics in soil inoculated with plant growth-promoting bacteria (PGPB) supplemented with varying levels of nitrogen fertilizer in the form of urea (0% N, 25% N, 50% N, 75% N, and 100% N). In the present experiment, sandy clay loam soil was used and incubated for four weeks, and the concentrations of NH4+‒N and NO3–‒N were monitored using the destructive method (Kjeldahl) to determine the mineralization rate of urea. Results showed higher NH4+‒N (11.880 mg/kg mineralized with UPMRB9N50 treatment) and NO3–‒N (20.060 mg/kg mineralized with UPMRB9N50 treatment) concentrations in the bacteria-treated soil compared to the uninoculated control. Urea-N remains higher (0.0353% and 0.0253% from UPMRB9N50 treatment in the first and second weeks, respectively) in bacteria-treated soil during the first two weeks, then gradually becomes zero towards the end of the observing period. Nitrogen (N) leaching loss was lower in bacterial inoculated soil compared to the control, and the leaching loss of N was greater with the increased N fertilizer rates. Cumulative N leaching loss is higher (29.797 mg/kg) in 100% N-treated soil than in other treatments. The findings observed that the beneficial bacteria could enhance the N mineralization to make the nutrient available for the crop while, at the same time, reducing leaching losses of fertilizer when supplied with a minimum amount of chemical fertilizer, thereby saving the input cost and protecting the environment.

Moderate water deficit and nitrogen application rate are conducive to improving the nitrogen uptake and yield of greenhouse tomatoes

Nowadays, improper irrigation and fertilization result in a waste of resources and a decrease in tomato production. In this study, we set three irrigation intervals (W1, W2 and W3 indicated upper and lower limit of irrigation of 65–75% θFC, 75–85% θFC and 85–95% θFC) and three nitrogen application rates (N1, N2 and N3 indicated nitrogen application rates of 120, 180 and 240 kg hm−2). The HYDRUS–2D model was first calibrated and validated using data collected during a two–year field investigation and then applied to explore the rules of soil water and nitrogen movement and root uptake. The Entropy weight TOPSIS model was optimized water and nitrogen management. Reliable estimates of soil nitrate nitrogen concentrations (R2 = 97%–99%, MRE = 0.05–0.19 and RMSE = 0.023–0.110), crop N uptake (R2 = 88%–99%, MRE = 0.17–0.44 and RMSE = 0.25–10.72), and soil water content (R2 = 82%–96%, MRE = 0.009–0.024 and RMSE = 0.003–0.007) were provided by HYDRUS–2D model. Based on the simulated results, the soil ammonium nitrogen was not easily affected by soil water movement and mainly distributed in 0–30 cm. W3 made soil water move deeper and carried nitrate nitrogen to accumulate in the deep soil comparison to W2 and W1. The combination of irrigation interval of 75–85% θFC and nitrogen application rate of 180 kg hm−2 improved root uptake, water use efficiency, nitrogen use efficiency and tomato yield. The evaluation result showed that N2W2 was the optimal water and nitrogen supply mode for our study. This study could promote the sustainable production of greenhouse tomatoes.

Melanization slows the rapid movement of fungal necromass carbon and nitrogen into both bacterial and fungal decomposer communities and soils.

Microbial necromass contributes significantly to both soil carbon (C) persistence and ecosystem nitrogen (N) availability, but quantitative estimates of C and N movement from necromass into soils and decomposer communities are lacking. Additionally, while melanin is known to slow fungal necromass decomposition, how it influences microbial C and N acquisition as well as elemental release into soils remains unclear. Here, we tracked decomposition of isotopically labeled low and high melanin fungal necromass and measured 13C and 15N accumulation in surrounding soils and microbial communities over 77 d in a temperate forest in Minnesota, USA. Mass loss was significantly higher from low melanin necromass, corresponding with greater 13C and 15N soil inputs. A taxonomically and functionally diverse array of bacteria and fungi was enriched in 13C and/or 15N at all sampling points, with enrichment being consistently higher on low melanin necromass and earlier in decomposition. Similar patterns of preferential C and N enrichment of many bacterial and fungal genera early in decomposition suggest that both microbial groups co-contribute to the rapid assimilation of resource-rich soil organic matter inputs. While overall richness of taxa enriched in C was higher than in N for both bacteria and fungi, there was a significant positive relationship between C and N in co-enriched taxa. Collectively, our results demonstrate that melanization acts as a key ecological trait mediating not only fungal necromass decomposition rate but also necromass C and N release and that both elements are rapidly co-utilized by diverse bacterial and fungal decomposers in natural settings. IMPORTANCE Recent studies indicate that microbial dead cells, particularly those of fungi, play an important role in long-term carbon persistence in soils. Despite this growing recognition, how the resources within dead fungal cells (also known as fungal necromass) move into decomposer communities and soils are poorly quantified, particularly in studies based in natural environments. In this study, we found that the contribution of fungal necromass to soil carbon and nitrogen availability was slowed by the amount of melanin present in fungal cell walls. Further, despite the overall rapid acquisition of carbon and nitrogen from necromass by a diverse range of both bacteria and fungi, melanization also slowed microbial uptake of both elements. Collectively, our results indicate that melanization acts as a key ecological trait mediating not only fungal necromass decomposition rate, but also necromass carbon and nitrogen release into soil as well as microbial resource acquisition.

Investigating nitrogen movement in North Pacific spiny dogfish (Squalus acanthias suckleyi), with focus on UT, Rhp2, and Rhbg mRNA abundance.

For ureosmotic marine elasmobranchs, the acquisition and retention of nitrogen is critical for the synthesis of urea. To better understand whole-body nitrogen homeostasis, we investigated mechanisms of nitrogen trafficking in North Pacific spiny dogfish (Squalus acanthias suckleyi). We hypothesized that the presence of nitrogen within the spiral valve lumen would affect both the transport of nitrogen and the mRNA abundance of a urea transporter (UT) and two ammonia transport proteins (Rhp2, Rhbg) within the intestinal epithelium. The in vitro preincubation of intestinal tissues in NH4Cl, intended to simulate dietary nitrogen availability, showed that increased ammonia concentrations did not significantly stimulate the net uptake of total urea or total methylamine. We also examined the mRNA abundance of UT, Rhp2, and Rhbg in the gills, kidney, liver, and spiral valve of fasted, fed, excess urea fed, and antibiotic-treated dogfish. After fasting, hepatic UT mRNA abundancewas significantly lower, and Rhp2 mRNA in the gills was significantly higher than the other treatments. Feeding significantly increased Rhp2 mRNA levels in the kidney and midspiral valve region. Both excess urea and antibiotics significantly reduced Rhbg mRNA levels along all three spiral valve regions. The antibiotic treatment also significantly diminished UT mRNA abundance levels in the anterior and midspiral valve, and Rhbg mRNA levels in the kidney. In our study, no single treatment had significantly greater influence on the overall transcript abundance of the three transport proteins compared to another treatment, demonstrating the dynamic nature of nitrogen balance in these ancient fish.

Nitrogen transporters along the intestinal spiral valve of cloudy catshark (Scyliorhinus torazame): Rhp2, Rhbg, UT

As part of their osmoregulatory strategy, marine elasmobranchs retain large quantities of urea to balance the osmotic pressure of the marine environment. The main source of nitrogen used to synthesize urea comes from the digestion and absorption of food across the gastrointestinal tract. In this study we investigated possible mechanisms of nitrogen movement across the spiral valve of the cloudy catshark (Scyliorhinus torazame) through the molecular identification of two Rhesus glycoprotein ammonia transporters (Rhp2 and Rhbg) and a urea transporter (UT). We used immunohistochemistry to determine the cellular localizations of Rhp2 and UT. Within the spiral valve, Rhp2 was expressed along the apical brush border membrane, and UT was expressed along the basolateral membrane and the blood vessels. The mRNA abundance of Rhp2 was significantly higher in all regions of the spiral valve of fasted catsharks compared to fed catsharks. The mRNA abundance of UT was significantly higher in the anterior spiral valve of fasted catsharks compared to fed. The mRNA transcript of four ornithine urea cycle (OUC) enzymes were detected along the length of the spiral valve and in the renal tissue, indicating the synthesis of urea via the OUC occurs in these tissues. The presence of Rhp2, Rhbg, and UT along the length of the spiral valve highlights the importance of ammonia and urea movement across the intestinal tissues, and increases our understanding of the mechanisms involved in maintaining whole-body nitrogen homeostasis in the cloudy catshark.

Effects of nitrogen-contaminated irrigation methods on the growth and development of rice and nitrogen movement through cultivation layers in the Red River Delta, Vietnam

The experiment was conducted in the field to evaluate the effect of nitrogen-contaminated irrigation methods on the growth, development, and yield of rice (Oryza sativa L.) and the movement of nitrogen through the cultivation layers. The experiment was arranged in a Randomized Complete Block Design with three replicates. It was conducted in the summer season of 2022 at the rice experiment area of the Faculty of Environment, Vietnam National University of Agriculture, with three treatments, namely: T1 (control; continuous flooding (CF) with clean water), T2 (alternate wetting and drying (AWD) with nitrogen-contaminated water), T3 (CF with nitrogen-contaminated water). Experimental results indicated that different irrigation methods with nitrogen-contaminated water affect the growth, development, and yield of rice and the movement of nitrogen in the cultivated soil layers (at 35 cm depth, 70 cm – depth, 120 cm – depth). T2 treatment was the best irrigation method for reducing the amount of water for irrigation of rice and limiting the amount of excess nitrogen on the arable soil layers, which affects the quality of shallow groundwater. The movement of nitrogen nitrates through shallow groundwater was less than that of ammonium nitrogen form, and there was no difference in nitrogencontaminated irrigation using water-saving (T2) and flooded irrigation (T3) methods and within the safe threshold (QCVN 09-MT:2015/BTNMT).

Application of Activated Seashells and Sand Armor for Disrupting N and P Release from River Sediments

We investigated the applicability of oyster (OS) and mussel shells (MS) as capping materials to inhibit the movement of nitrogen (N) and phosphorus (P) from river sediments. OS and MS are difficult to dispose of as waste, and have been used environmentally to clean up sediments contaminated with nitrogen and phosphorus. OS and MS increased the nutrient adsorption efficiency through simple heat treatment. The effectiveness of OS and MS capping with sand armor (SA) was evaluated in laboratory incubation experiments for 63 d. The sediments were capped with an active capping material (OS or MS) and then with either 1 cm or 3 cm SA. The pH and EC values were remarkably high under MS capping conditions because Ca2+ and Mg2+ were eluted from the MS material. The elution of Ca2+ and Mg2+ negatively affected the inhibition of NH4-N release by MS capping. OS capping demonstrated better performance for blocking the release of NH4-N and T-N than that of MS capping; the efficiency was enhanced by adding a 3 cm SA layer on top of the MS layer. In contrast, the PO4-P and T-P releases from the river sediments were effectively impeded by MS capping. OS capping with a 3 cm SA layer (OS/SA3) was recommended as the best capping strategy for inhibiting N and P releases from river sediments. The capping efficiencies of OS/SA3 for NH4-N, T-N, PO4-P, and T-P were 92.2%, 51.4%, 101.3%, and 93.3%, respectively.

Simulation of water and nitrogen movement mechanism in cold regions during freeze-thaw period based on a distributed nonpoint source pollution model closely coupled water, heat, and nitrogen processes at the watershed scale.

The nitrogen cycle in cold regions during the freeze-thaw period is complex. Although previous studies have investigated the phenomenon of nitrogen transport and transformation, the underlying mechanisms are vague. Existing models have limitations in terms of loose coupling or weak physical mechanisms. Therefore, a new distributed nonpoint source pollution model, the water and energy transfer processes and nitrogen cycle processes model in cold regions, was developed in this study, with closely coupled water, heat, and nitrogen processes at the watershed scale. The model considered the driving effects of pressure, gravity, solute, and temperature potentials on water and nitrogen movement in soil and the transformation relationship among nitrogen forms. Physical evaluation and simulations were conducted for the Heidingzi River Watershed during two freeze-thaw periods: 2017-2018 and 2018-2019. The soil temperature absolute error was < 0.82℃. The relative errors in stratified liquid water, soil nitrogen content, river flow rate, and river nitrogen concentration were mostly < 10%. Nitrogen transport with water had an obvious "upward agglomeration effect" during the freezing period and a "concentrated release effect" during the thawing period, which was attributed to changes in soil water potential as the freezing front moved down. Disregarding the effects of solute potential and temperature potential will result in an underestimate of the outflow of pollutants during the thawing period. The model can be applied to reveal water quality deterioration in cold regions during thawing.

Effects of autumn plowing on the movement and correlation of moisture, heat and nitrate nitrogen in seasonal freeze-thaw soil

Effects of autumn plowing on the movement and correlation of moisture, heat and nitrate nitrogen in seasonal freeze-thaw soil

Does resource exchange in ectomycorrhizal symbiosis vary with competitive context and nitrogen addition?

Ectomycorrhizal symbiosis is essential for the nutrition of most temperate forest trees and helps regulate the movement of carbon (C) and nitrogen (N) through forested ecosystems. The factors governing the exchange of plant C for fungal N, however, remain obscure. Because competition and soil resources may influence ectomycorrhizal resource movement, we performed a 10-month split-root microcosm study using Pinus muricata seedlings with Thelephora terrestris, Suillus pungens, or no ectomycorrhizal fungus, under two N concentrations in artificial soil. Fungi competed directly with roots and indirectly with each other. We used stable isotope enrichment to track plant photosynthate and fungal N. For T. terrestris, plants received N commensurate with the C given to their fungal partners. Thelephora terrestris was a superior mutualist under high-N conditions. For S. pungens, plant C and fungal N exchange were not coupled. However, in low-N conditions, plants preferentially allocated C to S. pungens rather than T. terrestris. Our results suggest that ectomycorrhizal resource transfer depends on competitive and nutritional context. Plants can exchange C for fungal N, but coupling of these resources can depend on the fungal species and soil N. Understanding the diversity of fungal strategies, and how they change with environmental context, reveals mechanisms driving this important symbiosis.

Carbon for nutrient exchange between Lycopodiella inundata and Mucoromycotina fine root endophytes is unresponsive to high atmospheric CO2

Non-vascular plants associating with arbuscular mycorrhizal (AMF) and Mucoromycotina ‘fine root endophyte’ (MFRE) fungi derive greater benefits from their fungal associates under higher atmospheric [CO2] (a[CO2]) than ambient; however, nothing is known about how changes in a[CO2] affect MFRE function in vascular plants. We measured movement of phosphorus (P), nitrogen (N) and carbon (C) between the lycophyte Lycopodiella inundata and Mucoromycotina fine root endophyte fungi using 33P-orthophosphate, 15 N-ammonium chloride and 14CO2 isotope tracers under ambient and elevated a[CO2] concentrations of 440 and 800 ppm, respectively. Transfers of 33P and 15 N from MFRE to plants were unaffected by changes in a[CO2]. There was a slight increase in C transfer from plants to MFRE under elevated a[CO2]. Our results demonstrate that the exchange of C-for-nutrients between a vascular plant and Mucoromycotina FRE is largely unaffected by changes in a[CO2]. Unravelling the role of MFRE in host plant nutrition and potential C-for-N trade changes between symbionts under different abiotic conditions is imperative to further our understanding of the past, present and future roles of plant-fungal symbioses in ecosystems.

Nitrogen and phosphorus distribution in plant, soil, and leachate as affected by liquid hog manure and chemical fertilizers

A 2 yr field study was conducted on a coarse-textured soil in Manitoba, Canada, to investigate the effects of liquid hog manure (LHM) and chemical fertilizer application on barley (2005) and red spring wheat (2006) yields, crop nutrient uptake, and nitrogen (N) and phosphorus (P) movement to the environment. The treatments were LHM applied at two rates as 22 000 L·ha−1 (2500 gal·ac−1, abbreviated as M2500) and 43 000 L·ha−1 (5000 gal·ac−1, abbreviated as M5000) and two rates of chemical fertilizer to match total N and P in LHM treatments, F2500 and F5000, along with an unamended control. The M5000 and M2500 treatments showed similar grain yield and N and P uptake. However, M5000 and M2500 significantly increased grain yield by 67% and 78%, respectively, compared with the control in 2005. In 2006, wheat grain yields from M2500 and M5000 were 71% and 86% greater than the control. In 2005, leachate NO3-N concentrations and leaching loads were higher with chemical fertilizers than M2500. In 2005, the apparent recovery of applied N as leachate was 35% and 23% in F5000 and F2500 treatments, whereas it was 6% and 7% of applied N in M5000 and M2500 plots, respectively. However, the application of M5000 resulted in P accumulation near the surface and may increase the potential risk of P loss with runoff. Our results show that applying LHM at moderate rates (M2500) may ensure desirable crop yields comparable to higher rates of nutrient application with minimal potential losses relative to higher rates.

Study on Gas Diffusion in Fire Working Areas of Oil and Gas Pipelines Based on Temperature Difference.

When a pipeline is under fire safety work construction, the stack effect of the pipeline will increase the diffusion rate of nitrogen, reduce the oxygen content, and cause asphyxia. To prove the influence of the stack effect of the pipeline on the nitrogen movement in the pipeline and put forward effective ventilation control measures, the formation mechanism, gas diffusion law, and ventilation parameters of the stack effect of the oil and gas pipelines are studied through theoretical derivation and numerical simulation. The results show that the nitrogen concentration at the height of the breathing zone in the hot zone first increases and then decreases along the axial distance. The larger the temperature difference, the faster the diffusion speed of nitrogen in the fire safety work area, and the lower the oxygen concentration. When the temperature difference increases to 30 °C, the maximum oxygen concentration in the work area is 0.177; to control the problem of low oxygen content caused by the stack effect, three ventilation schemes are put forward. Through the analysis that installing fans symmetrically on both sides, 4 m away from the pipe opening, can effectively reduce the stack effect intensity when the optimal working wind speed of the fan is 4 m/s. The findings of this study can help in better understanding the causes of the chimney effect during pipeline fire safety work and provide theoretical basis for controlling personnel suffocation caused by the chimney effect.

How does the functionality of the pore system affects inorganic nitrogen storage in volcanic ash soils?

The dynamics of water in the soil permit the movement, storage and redistribution of nitrogen (N) within productive and natural agro-ecosystems. The objective of this research was to determine the functionality of the soil’s porous system, using capacity and intensity parameters in two volcanic soils (Andisol and Ultisol) under agricultural use and to present a new approach of how soils have the capacity to store inorganic N throughout time. Undisturbed soil core samples (230 cm3 and 250 cm3) were collected at four depths: 0–20; 20–40; 40–70; 70–100 cm. Capacity parameters: air capacity (AC) and plant available water (PAW) and intensity parameters: saturated hydraulic conductivity (Ks) and pore connectivity index (C2) were measured and calculated. Greater average PAW (48%) was determined at the previously mentioned depths in the Andisol as compared to the Ultisol (32%). Calculated values-diffusive NO3- fluxes (DNF) as a function of soil water content (SWC) were determined in the pF curve (R2 = 0.98; p < 0.0001; fitted model proposed by Clunes, 2020). As SWC increased in PAW, the DNF did as well (DNF in Andisol, from 480 nmol N cm–2 h–1 to 710 nmol N cm–2 h–1). An inverse relationship was observed between the DNF and the air-filled porosity (ea); the slope was about –1.02 in both soils. The DNF presented a significant relationship with the C2 index in the Andisol (R2 > 0.80; Sy.x > 0.02). In contrast, the Ultisol at the depth of 0–20 cm presented a highly negative relationship between DNF and C2 (R2 = 0.99), due to tillage. The relationship observed here between intensity parameters and DNF revealed a dynamic factor of N availability in the soil. As water increased in PAW and the continuity values between the pores augmented, this allowed for an increase in the available N in a soil volume. We propose that soils have the capacity to physically store inorganic N in the PAW and the functionality of the pore system (their ability to transport water and distribute nutrients throughout the profile). Improving our comprehension in this regard will allow us to increase fertilization efficiency and could also contribute to closing nutrient cycles within an agro-ecosystem.