Nitrogen Fractions Research Articles

Nitrogen evolution during membrane-covered aerobic composting: Interconversion between nitrogen forms and migration pathways

Aerobic composting is a promising technology for converting manure into organic fertilizer with low capital investment and easy operation. However, the large nitrogen losses in conventional aerobic composting impede its development. Interconversion of nitrogen species was studied during membrane-covered aerobic composting (MCAC) and conventional aerobic composting, and solid-, liquid-, and gas-phase nitrogen migration pathways were identified by performing nitrogen balance measurements. During the thermophilic phase, nitrogenous organic matter degradation and therefore NH3 production were faster during MCAC than uncovered composting. However, the water films inside and outside the membrane decreased NH3 release by 13.92%–22.91%. The micro-positive pressure environment during MCAC decreased N2O production and emission by 20.35%–27.01%. Less leachate was produced and therefore less nitrogen and other pollutants were released during MCAC than uncovered composting. The nitrogen succession patterns during MCAC and uncovered composting were different and NH4+ storage in organic nitrogen fractions was better facilitated during MCAC than uncovered composting. Overall, MCAC decreased total nitrogen losses by 33.24%–50.07% and effectively decreased environmental pollution and increased the nitrogen content of the produced compost.

The introduction of nitrogen from coal into the surface watershed nitrogen cycle due to coal mining activity

Human activity has doubled the turnover rate of the terrestrial nitrogen cycle, leading to a series of environmental problems. A little-studied nitrogen source in terrestrial and aquatic environments is the nitrogen release associated with rock strata. Southwest China features the largest continuous karsts in the world, featuring a fragile ecological environment but abundant coal resources. The current study selected a typical coal mining area to evaluate the migration and transformation of nitrogen related to coal mining in surface watershed. The findings reveal that the total nitrogen in coal seams was as high as 10,162.3 mg/kg, mainly in the form of organic nitrogen, followed by NH4+-N, while the content of NO3−-N was negligible. Based on the isotope fractionation and the co-evolution between Δ15NNO3-NH4 and δ15N-NO3−/δ15N-NH4+, coal mining changed the coal seams' oxidation-reduction state, resulting in the mineralization of organic nitrogen to NH4+-N. Next, NH4+-N gradually oxidized to NO3−-N. Various forms of coal-origin nitrogen may be leached out by acid mine drainage (AMD), potentially contributing >10 % of NO3−-N and 90 % of NH4+-N to the surface river. Another nitrogen source that requires serious consideration is the wide use of ammonium nitrate explosives in coal mining, as blasting residues may contribute about another 10 % to NO3−-N in surface water. Since organic nitrogen accounts for >90 % of extractable nitrogen, the release of coal-origin nitrogen may contribute much more to the total nitrogen in surface water than to NO3−-N. Based on the fractionation of nitrogen and oxygen isotopes of nitrate, low-pH AMD promotes the volatilization of nitrate in the form of nitric acid. The conversion of different forms of nitrogen in AMD will be the focus of future attention.

Effect of Mixing Peanut Vine on Fermentation Quality, Nitrogen Fraction and Microbial Community of High-Moisture Alfalfa Silage

Fresh alfalfa is difficult to ensile successfully because of its high moisture content and greater susceptibility to spoilage by Clostridia, Bacilli or Enterobacter. In this study, we evaluated the effects of mixing high-moisture alfalfa with peanut vine in different proportions on the bacterial communities and fermentation characteristics of silage. The high-moisture alfalfa and peanut vine were mixed at ratios of 10:0 (CK), 8:2 (TI), 7:3 (T2), 6:4 (T3) and 5:5 (T4), respectively. For each treatment, silos (25 × 35 cm) were anaerobically fermented in darkness at room temperature and analyzed after 45 days. The results showed that the CK silage was weakly fermented, as indicated by a low lactic acid concentration, a high pH value, and high levels of propionic acid (PA), butyric acid (BA) and ammonia nitrogen (NH3-N). As the proportion of peanut vine in the mixture increased, the pH level decreased, and levels of BA, propionic acid, NH3-N, crude protein(CP), nonprotein nitrogen and soluble protein also declined (p < 0.05), while the lactic acid concentration increased and levels of neutral detergent fiber (NDF) and water-soluble carbohydrates (WSC) also rose (p < 0.05). A protein component analysis of silage mixtures using the Cornell Net Carbohydrate and Protein System (CNCPS) showed that the content of the nonprotein nitrogen component (PA) decreased when the proportion of peanut vine increased, whereas the content of rapidly degraded protein (PB1) increased. Mixing with peanut vine also influenced the distribution of the bacterial community. Compared with the CK silage, the relative abundances of Enterococcus, Garciella and Anaerosporobacter in T2, T3 and T4 were significantly lower, while the relative abundance of Lactobacillus was significantly higher. In the T2, T3 and T4 groups, Garciella and Anaerosporobacter were not detected. In summary, in this study, we ensiled high-moisture alfalfa, which was weakly fermented. We found that mixing with peanut vine improved fermentation quality and optimized the structure of the bacterial community. Therefore, to improve the fermentation quality and nutritional value of silage, high-moisture alfalfa should be ensiled with at least 30% peanut vine.

Modeling of growth of the macroalga Ulva sp. in a controlled photobioreactor based on nitrogen accumulation dynamics

ABSTRACT Macroalgal biomass production models that capture nutrient dynamics, temperature, light and salinity are important for the design and operation of large-scale farms. The goal of this study is to understand how the nitrogen fertilizing regime, relating to dose (µM N week−1), amplitude (µM N) and duration (hours) of fertilization, affects the dynamics of nitrogen content and biomass production of Ulva sp. We hypothesize that the nitrogen fertilizing regime controls the Ulva Nitrogen Use Efficiency (NUE), defined here as the fraction of fertilizer nitrogen that is utilized and allocated to yield N, and, accordingly, also nitrogen assimilation in the biomass and the growth rate. We test this hypothesis by measuring internal nitrogen and biomass weight and by calculating NUE under various fertilization regimes in controlled photobioreactors. Based on these experimental data, we developed a biomass productivity model that predicts nitrogen and biomass dynamics temporally over three weeks of cultivation. This study highlights efficient fertilizing regimes and enables the development of a comprehensive understanding of the dynamic relationship between external N, internal N and biomass production of Ulva sp. under varying external N levels, which is important for real-world agricultural applications. This study provides a better understanding of the external N-internal N-biomass triangle leading to an improved dynamic cultivation model, enabling better control of nutrient application and biomass production in macroalgal farming for a sustainable marine bioeconomy.

Straw mulch improves soil carbon and nitrogen cycle by mediating microbial community structure and function in the maize field.

This study was conducted to investigate the capability of the microbial community characteristics and soil variables to promote carbon and nitrogen cycles in maize fields under straw mulch. We covered the surface soil of the maize field with different amounts of wheat straw (0 kg/ha, 2,250 kg/ha, and 4,500 kg/ha) and used 16S rRNA and ITS sequencing, Biology ECO-plate, traditional enzymology, TOC analyzer, and HPLC to measure bacterial and fungal community composition and functions, characteristics of microbial carbon source metabolism, carbon and nitrogen fraction, enzyme activity, and organic acid content in the maize rhizosphere and non-rhizosphere. The results indicated that short-term straw mulch insignificantly affected the alpha diversity of bacterial and fungal communities whereas significantly influenced their beta diversity. The results of functional prediction revealed that straw mulch considerably boosted the relative abundances of bacteria belonging to chemoheterotrophy, aerobic chemoheterotrophy, ureolysis, and nitrogen fixation and inhibited fermentation and nitrate reduction in maize rhizosphere soil. These processes primarily drove the C and N cycles in soil. Straw mulch also improved fungal saprotrophs by raising the proportion of Chaetomiaceae and Chaetosphaeriaceae. The Biology ECO-plate results illustrated that straw mulch weakened the metabolism capacity of microbial labile carbon resources. As a result, the labile C and N fractions were raised under straw mulch. Our results also showed that straw mulch primarily regulated the microbial community structure in rhizosphere soil by significantly decreasing Firmicutes and Ascomycota relative abundance while increasing Basidiomycota. The fungal community structure is more than bacterial for affecting soil microbial biomass carbon, readily oxidizable organic carbon, dissolved organic carbon, available nitrogen, ammonium, and nitrate directly and indirectly through malic acid content and cellulase, protease, and amylase activity. Overall, our findings imply that straw mulch might influence the bacterial and fungal community structures, thereby boosting the production of labile C and N components and accelerating the C and N cycle in maize fields.

Equilibrium partitioning and isotopic fractionation of nitrogen between biotite, plagioclase, and K-feldspar during magmatic differentiation

A significant portion of the continental crust is composed of plutonic igneous rocks. However, little is known about the geochemical behaviour of N between the different minerals during magmatic differentiation. To provide new constraints for the behaviour of N during crust formation, we have characterised the geochemistry of nitrogen (N) in the compositionally zoned calc-alkaline pluton at Loch Doon, SW Scotland. We present N concentration and N isotope values for whole-rock data alongside biotite, plagioclase and K-feldspar mineral separates and assess the degree to which these data preserve equilibrium partitioning during magmatic differentiation. We show that whole rock likely inherited its N contents and δ15N signatures from the initial source composition and that this signature is homogenous at a pluton scale. Whilst the whole-rock data are best explained as crust-derived N in the source, the degree of homogenisation across a pluton scale is inconsistent with empirical N diffusivities, ruling out syn-emplacement crustal assimilation as the source of N. Instead, our data suggest a crustal signature inherited from depth associated with the Iapetus subduction zone. At a mineral scale, we find that N preferentially partitions into the feldspars over mica in this system in the order K-feldspar > plagioclase ≈ biotite > quartz, with average mineral–mineral distribution coefficients of DN plagioclase-biotite = 1.3 ± 0.6 and DN Kspar-biotite = 2.8 ± 0.6. Partitioning is accompanied by a large and near constant equilibrium isotope fractionation factor between biotite and both feldspars (averages are Δ15NPlag-Biotite = +7.8 ± 1.2‰ and Δ15NKspar-Biotite = +7.9 ± 1.0‰). In contrast, Δ15NKspar-Plagioclase closely approximates 0‰, where both minerals show δ15N values overlapping with the bulk rock δ15N values. These results show that mica crystallisation generates a 15N-depleted reservoir within plutonic rocks. Moreover, our dataset suggests that feldspars might be a more significant host of N in the igneous portion of Earth’s continental and oceanic crust than previously thought.

Impact of Long-Term Application of FYM and Fertilizer Nitrogen on Soil Aggregation and Aggregate Bound Nitrogen Fractions and Nitrogen Mineralization Pattern in Different Size Soil Aggregates: A Review

This review highlights the impact of long-term application of FYM and fertilizer nitrogen on soil aggregation and aggregate bound nitrogen fractions and nitrogen mineralization pattern in different size soil aggregates. Organic manures are an important factor to maintain the soil fertility level because soil organic matter is regarded as a key indicator when assessing soil quality. The integrated application of inorganic and organic amendments leads to increase in both the inorganic fractions (ammonical and nitrate nitrogen) as compare to their alone application. Organic manures and residues that are added to the soil increase the total nitrogen content of the soil by protecting it chemically and physically against microbial degradation. Through FYM and crop root biomass (rhizodeposition), organic matter and fertilizers have been added to the soil on a regular basis during the past 41 years, and the building of nitrogen shows that nitrogen is physically protected within macro aggregates.

A novel composting system for mitigating ammonia emissions and producing nitrogen-rich organic fertilizer

Ammonia emissions not only lead to environmental pollution but also reduce the quality of compost products. Here, a novel composting system (condensation return composting system, CRCS) was designed for mitigating ammonia emissions. The results showed that the CRCS reduced ammonia emissions by 59.3% and increased the total nitrogen content by 19.4% compared with the control. By integrating the results of nitrogen fraction conversion, ammonia-assimilating enzyme activity, and structural equation modeling, it was found that the CRCS facilitated the conversion of ammonia to organic nitrogen by stimulating ammonia-assimilating enzyme activity and ultimately retained nitrogen in the compost product. Moreover, the pot experiment confirmed that nitrogen-rich organic fertilizer produced by the CRCS significantly increased the fresh weight (45.0%), root length (49.2%), and chlorophyll content (11.7%) of pakchoi. This study provides a promising strategy for mitigating ammonia emissions and producing nitrogen-rich organic fertilizer with high agronomic value.

Biochar from animal manure: A critical assessment on technical feasibility, economic viability, and ecological impact

AbstractAnimal manure has been used to manage soil fertility since the dawn of agriculture. It provides plant nutrients and improves soil fertility. In the last decades, animal husbandry has been significantly expanded globally. Its economics were optimized via the (international) trade of feed, resulting in a surplus of animal manure in areas with intensive livestock farming. Potentially toxic elements (PTEs), pathogenic microorganisms, antibiotic residues, biocides, and other micropollutants in manure threaten animal, human, and environmental health. Hence, manure application in crop fields is increasingly restricted, especially in hotspot regions with intensive livestock activities. Furthermore, ammonia volatilization and greenhouse gas (GHG) emissions during manure storage, field application, and decomposition contribute to air pollution and climate change. Conventional manure management scenarios such as composting and anaerobic digestion partially improve the system but cannot guarantee to eliminate sanitary and contamination risks and only marginally reducing its climate burden. Hence, this review discusses the potential of pyrolysis, the thermochemical conversion under oxygen‐limited conditions as an alternative treatment for animal manure providing energy and biochar. Manure pyrolysis reduces the bioavailability of PTEs, eliminates pathogenic microorganisms and organic micropollutants, and reduces GHG emissions. Pyrolysis also results in the loss of nitrogen, which can be minimized by pretreatment, that is, after removing soluble nitrogen fraction of manure, for example, by digestion and stripping of ammonia–nitrogen or liquid–solid separation. However, conclusions on the effect of manure pyrolysis on crop yield and fertilization efficiencies are hampered by a lack of nutrient mass balances based on livestock unit equivalent comparisons of manure and manure biochar applications. Hence, it is essential to design and conduct experiments in more practically relevant scenarios and depict the observations based on the amount of manure used to produce a certain amount of biochar.

Impact of fertilization and grazing on soil N and enzyme activities in a karst pasture ecosystem

The biggest obstacle to economic development in karst areas comes from the ecological crisis, so healthy soil and adequate food are important. Soil nitrogen (N) is an important factor in maintaining soil quality. Understanding the changes in soil N fractions and enzyme activities under different management practices is important to maintain sustainable pastureland in karst areas. In this study, we investigated how grazing and fertilization affect different soil nitrogen fractions and enzyme activities of karst pastureland. The four treatments were unused land (UL, undisturbed utilization), abandoned-grazing pastureland (APL, grazing for three years followed by abandonment for six years), grazing pastureland (GPL, controlled grazing without fertilizer) and fertilized-grazing pastureland (FGPL, controlled grazing + fertilizer), with the aim of determining the management practices that is most beneficial to soil N in the area. Our results indicated that FGPL is the most beneficial in enhancing soil N fractions. This is reflected in greater total nitrogen (TN), alkaline driven nitrogen (NOH), inorganic nitrogen (TON), anaerobic mineralized nitrogen (The average increase in each soil layer over UL was 1.43 times; TMN), microbial biomass nitrogen (The average increase in each soil layer over UL was 3.51 times; MBN), amino acid nitrogen (AAN), amino sugar nitrogen (ASN), acidolyzed unknown nitrogen (TUN) and unacidified nitrogen (AIN) in FGPL soils. Likewise, greater enzyme activities were also found in nitrogen conversion-related enzymes (soil urease (S-UE), soil N-acetyl-β-D-aminoglucosidase (S-NAG), nitrate reductase (S-NR), and soil acid protease (S-ACPT)). In addition, the combination of grazing and balanced nutrient inputs slowed soil acidification and maintained high levels of total phosphorus (TP) and total potassium (TK). In contrast, the soil N fractions responded significantly to APL (low TN and plant effective nitrogen), while insufficient conversion capacity (enzyme activity, MBN) was the main reason for the compromised soil N availability at GPL. Government policy makers and livestock producers should encourage controlled grazing with proper fertilizer supplementation, and avoid prolonged abandonment of grazing lands.

Clipping Effect on the Grain Nitrogen and Protein Fractions of Ancient and Old Wheats Grown in a Mediterranean Environment

This study is the first to assess the effects of clipping, cultivar, season, and their interactions on the protein composition of six old and ancient wheat cultivars (n = 6). For this, nitrogen content, the proportion of wheat protein fractions, and the molecular weight distribution of the extractable and unextractable glutenin polymers were investigated as a function of cultivar and clipping in two consecutive seasons. The relationships between genotypic variation in grain nitrogen and protein fraction content under clipping and non-clipping conditions were also assessed. Clipping delayed and shortened the grain filling period of all of the cultivars. The protein composition of some cultivars behaved differently to clipping due to differences in the environmental conditions of S1 (exceptional dry season) and S2 (rainy season). In S1, clipping decreased the ratio of gliadins over glutenins (GLI/GLU) (<1) of Cappelli and Giovanni Paolo, while in S2, clipping improved the GLI/GLU of Giovanni Paolo, Monlis, and Norberto. The unextractable polymeric proteins were not affected by clipping. Khorasan was shown to be indifferent to clipping in S1 and S2. These results suggest that it is possible to have ancient/old wheats suitable for a dual-purpose system, in different climatic conditions, while maintaining good grain quality traits. The increased market demand for ancient and old wheats presents an economic opportunity for farmers who adopt the dual-purpose technique to cultivate these resilient crops again and increase their profit margins and revenues.

The results of the initial introduction of <i>Bupleurum aureum</i> Fisch. ex Hoffm. in the middle taiga subzone of the Komi Republic

The paper summarizes the results of a long-term introduction study of plants of golden boletus in the collection of medicinal plants of the Botanical Garden of the Institute of Biology of the Komi Scientific Center of the Ural Branch of the Russian Academy of Sciences. The primary introduction of the species into new growing conditions became possible only by transferring living plants to cultivation from the places of natural growth of the Tomsk Region, followed by propagation of plants from seeds of their own reproductions. The optimal methods of seed propagation of this species in the conditions of the North were revealed: winter sowing with freshly harvested seeds and self-sowing of seeds with further transplantation of emerging seedlings to a new plot with a feeding area of 30 30 cm golden is distinguished by high survival rate, winter hardiness and stability in the coenosis. The mass transition of plants into the generative period occurred in the second third year of life. The phenology and dynamics of plant growth have been studied. The rhythm of the seasonal development of plants in. golden in culture in the North corresponds to the new soil and climatic conditions of cultivation. The growing season is 96100 days. Golden boletus regularly forms full-fledged seeds, which, after undergoing natural stratification under snow cover, germinate in the spring and give a large self-sowing. Real seed productivity (the number of mature full-fledged seeds) in plants c. golden of different ages varies over the years from 420 to 570 seeds per shoot. The morphobiological signs of the generative shoot were studied in culture and the amplitude of their variability was determined. High and very high levels of individual variability of signs of the floral zone of the shoot indicate the possibility of targeted selection of more productive individuals within the population. For the first time, data on the content of proteins and its amino acid composition in plants are presented. The mass fraction of nitrogen (in terms of crude protein) in the aboveground phytomass was 1,51,8%. In proteins from aboveground phytomass, 17 amino acids were identified, including 7 essential ones (threonine, valine, methionine, isoleucine, leucine, phenylalanine, lysine). The proportion of essential amino acids averaged 39% of the total. The highest rates were noted for amino acids: glutamic, aspartic, leucine, lysine, alanine and valine 13,1, 10,7, 9,2, 8,1, 6,7 and 6,2% respectively.

The Nitrogen Cycling Key Functional Genes and Related Microbial Bacterial Community α−Diversity Is Determined by Crop Rotation Plans in the Loess Plateau

Soil nitrogen cycling microbial communities and functional gene α−diversity indicate soil nitrogen cycling ecological functions and potentials. Crop rotation plans affect soil nitrogen fractions and these indicators. We sequenced soil samples from four crop rotation plans (fallow, winter wheat monoculture, pea-winter wheat-winter wheat-millet rotation, and corn-wheat-wheat-millet rotation) in a long-term field experiment. We examined how microbial communities and functional gene α−diversity changed with soil nitrogen fractions and how nitrogen fractions regulated them. Planting crops increased the abundance and richness of nitrogen cycling key functional genes and bacterial communities compared with fallow. The abundance and richness correlated positively with nitrogen fractions, while Shannon index did not. The abundance increased with soil total nitrogen (STN) and potential nitrogen mineralization (PNM), while Shannon index showed that nitrogen cycling key functional genes increased and then decreased with increasing STN and PON. Introducing legumes into the rotation improved the α−diversity of nitrogen cycling key functional genes. These results can guide sustainable agriculture in the Loess Plateau and clarify the relationship between nitrogen fractions and nitrogen cycling key functional genes.

Simulation and Control Strategy Study of the Hydrogen Supply System of a Fuel Cell Engine

The hydrogen supply system is one of the important components of a hydrogen fuel cell engine, and its performance has an important impact on the economy and power of the engine system. In this paper, a hydrogen supply system based on cyclic mode is designed for a hydrogen fuel cell stack with a full load power of 150 kW, and the corresponding hydrogen fuel cell engine simulation model is built and validated. The control strategy of the fuel cell hydrogen supply system is developed, and its effect is verified through bench tests. The results show that the developed control strategy can keep the volume fraction of nitrogen below 6%, the hydrogen excess ratio does not exceed 1.5 under medium and high operating conditions, the anode pressure is relatively stable, and the stack can operate efficiently and reliably.

Hyperbaric air mobilizes stem cells in humans; a new perspective on the hormetic dose curve.

Hyperbaric air (HBA) was first used pharmaceutically in 1662 to treat lung disease. Extensive use in Europe and North America followed throughout the 19th century to treat pulmonary and neurological disorders. HBA reached its zenith in the early 20th century when cyanotic, moribund "Spanish flu pandemic" patients turned normal color and regained consciousness within minutes after HBA treatment. Since that time the 78% Nitrogen fraction in HBA has been completely displaced by 100% oxygen to create the modern pharmaceutical hyperbaric oxygen therapy (HBOT), a powerful treatment that is FDA approved for multiple indications. Current belief purports oxygen as the active element mobilizing stem progenitor cells (SPCs) in HBOT, but hyperbaric air, which increases tensions of both oxygen and nitrogen, has been untested until now. In this study we test HBA for SPC mobilization, cytokine and chemokine expression, and complete blood count. Ten 34-35-year-old healthy volunteers were exposed to 1.27ATA (4 psig/965 mmHg) room air for 90 min, M-F, for 10 exposures over 2-weeks. Venous blood samples were taken: (1) prior to the first exposure (served as the control for each subject), (2) directly after the first exposure (to measure the acute effect), (3) immediately prior to the ninth exposure (to measure the chronic effect), and (4) 3 days after the completion of tenth/final exposure (to assess durability). SPCs were gated by blinded scientists using Flow Cytometry. SPCs (CD45dim/CD34+/CD133-) were mobilized by nearly two-fold following 9 exposures (p = 0.02) increasing to three-fold 72-h post completion of the final (10th) exposure (p = 0.008) confirming durability. This research demonstrates that SPCs are mobilized, and cytokines are modulated by hyperbaric air. HBA likely is a therapeutic treatment. Previously published research using HBA placebos should be re-evaluated to reflect a dose treatment finding rather than finding a placebo effect. Our findings of SPC mobilization by HBA support further investigation into hyperbaric air as a pharmaceutical/therapy.

Effects of Phenyllactic Acid on Fermentation Parameters, Nitrogen Fractions and Bacterial Community of High-Moisture Stylo Silage

To investigate the effect of phenyllactic acid (PLA) on the dynamic changes of high-moisture stylo silage, fresh stylo was ensiled with addition of PLA at the levels of 0, 1% and 2% using lab-level silage bags, where samples were collected on days 3, 7, 14 and 30 of ensiling fermentation to analyze fermentation parameters, nitrogen distribution and bacterial community. The results showed that PLA addition at ensiling led to the increase (p < 0.01) in dry matter content, lactic acid concentration and Flieg’s score of stylo silage as well as the decrease (p < 0.01) in dry matter loss, pH value and coliform bacteria population, with butyric acid only detected in the control group. It also resulted in the increase (p < 0.01) in true protein content and its proportion as well as the decrease (p < 0.01) in ammonia-N content and its proportion, almost with linearly dose effect. Sequencing analysis revealed that PLA addition led to the increase (p < 0.05) in Sobs, Shannon, Chao and Ace of bacterial community in the stylo silage, where the relative abundance of Enterobacter, Clostridium, and Kosakonia was decreased, and that of Lactobacillus, Enterococcus and Pantoea was increased. Furthermore, Kosakonia, Terriglobus, Sphingomonas and Sphingopyxis had an important role in the bacterial interaction network. It is suggested that PLA application at the level of 1–2% could improve silage quality of stylo silage via modifying bacterial community.

Effect of Marinating Temperature of Atlantic Herring on Meat Ripening, Peptide Fractions Proportion, and Antioxidant Activity of Meat and Brine

The temperature has a significant effect on cathepsin activity, but the effect of temperature on the ripening of marinades, and the formation of protein hydrolysis products, is less studied than other technological factors. The results of this study showed that herring marinated at 2 °C showed a higher mass yield, but lower non-protein nitrogen (NPN), peptides, and free amino acid fraction content, than after marinating at 7 and 12 °C. The higher temperature increased the free amino acid content the most, and decreased the hardness, as measured via sensory assessment, of the marinated meat. This was confirmed by the hardness measurement in the texture profile analysis. The highest activity of cathepsins D and B in the meat was found at 7 °C, while cathepsin L was found at 2 °C. Increasing the temperature by 10 °C increased the diffusion/loss of nitrogenous substances from the meat to the brine by 36%. The meat and brine showed high antioxidant activity, which depended on the marinating temperature, and originated mainly from the 5–10 or <5 kDa fraction. The meat had a higher ABTS (2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonate) activity than the brine, opposite to the DPPH (2,2-diphenyl-1-picrylhydrazyl radical) activity, while the FRAP (Ferric Reducing Antioxidant Power) capacity was similar for meat and brine. The fractionation of the meat and brine extracts increased the antioxidant potential of FRAP and ABTS only for the brine. The most hydrophobic peptides were released during marinating at 7 °C. The meat and brine were dominated by 2–4 kDa peptides, followed by 4–6 and 0.5–2 kDa. The higher temperature favored a higher proportion of <4 kDa than >4 kDa peptides in the brine.

An evaluation of nitrogen indicators for soil health in long‐term agricultural experiments

AbstractVarious soil health indicators that measure a chemically defined fraction of nitrogen (N) or a process related to N cycling have been proposed to quantify the potential to supply N to crops, a key soil function. We evaluated five N indicators (total soil N, autoclavable citrate extractable N, water‐extractable organic N, potentially mineralizable N, and N‐acetyl‐β‐D‐glucosaminidase activity) at 124 sites with long‐term experiments across North America evaluating a variety of managements. We found that 59%–81% of the variation in N indicators was among sites, with indicator values decreasing with temperature and increasing with precipitation and clay content. The N indicators increased from 6%–39% in response to decreasing tillage, cover cropping, retaining residue, and applying organic sources of nutrients. Overall, increasing the quantity of organic inputs, whether from increased residue retention, cover cropping, or rotations with higher biomass, resulted in higher values of the N indicators. Although N indicators responded to management in similar ways, the analysis cost and availability of testing laboratories is highly variable. Further, given the strong relationships of the N indicators with carbon (C) indicators, measuring soil organic C along with 24‐h potential C mineralization could be used as a proxy for N supply instead of measuring potentially mineralizable N or any other N indicator directly.

Study of Brewer's Spent Grain Environmentally Friendly Processing Ways.

This article is devoted to the study of the effect of electrochemically activated water (catholyte with pH 9.3) on organic compounds of the plant matrix of brewer's spent grain in order to extract various compounds from it. Brewer's spent grain was obtained from barley malt at a pilot plant by mashing the malt followed by filtration and washing of the grain in water and storing it at (0 ± 2) °C in craft bags. For the organic compound quantitative determination, instrumental methods of analysis (HPLC) were used, and the results were subjected to mathematical analysis. The study results showed that at atmospheric pressure, the alkaline properties of the catholyte showed better results compared to aqueous extraction with respect to β-glucan, sugars, nitrogenous and phenolic compounds, and 120 min was the best period for extraction at 50 °C. The excess pressure conditions used (0.5 ÷ 1 atm) revealed an increase in the accumulation of non-starch polysaccharide and nitrogenous compounds, while the level of sugars, furan and phenolic compounds decreased with increasing treatment duration. The waste grain extract ultrasonic treatment used revealed the effectiveness of catholyte in relation to the extraction of β-glucan and nitrogenous fractions; however, sugars and phenolic compounds did not significantly accumulate. The correlation method made it possible to reveal the regularities in the formation of furan compounds under the conditions of extraction with the catholyte: Syringic acid had the greatest effect on the formation of 5-OH-methylfurfural at atmospheric pressure and 50 °C and vanillic acid under conditions of excess pressure. Regarding furfural and 5-methylfurfural, amino acids had a direct effect at excess pressure. It was shown that the content of all furan compounds depends on amino acids with thiol groups and gallic acid; the formation of 5-hydroxymethylfurfural and 5-methylfurfural is influenced by gallic and vanillic acids; the release of furfural and 5-methylfurfural is determined by amino acids and gallic acid; excess pressure conditions promote the formation of furan compounds under the action of gallic and lilac acids. This study showed that a catholyte allows for efficient extraction of carbohydrate, nitrogenous and monophenolic compounds under pressure conditions, while flavonoids require a reduction in extraction time under pressure conditions.

Nitrogen fractionation in ammonia and its insights into nitrogen chemistry

Context. Observations of the nitrogen isotopic ratio 14N/15N in the interstellar medium are becoming more frequent thanks to increased telescope capabilities. However, interpreting these data is still puzzling. In particular, measurements of 14N/15N in diazenylium have revealed high levels of anti-fractionation in cold cores, which is challenging to explain. Aims. By using astrophysical simulations coupled with a gas-grain chemical code, it has been suggested that the 15N-depletion in prestellar cores could be inherited from the initial stages, when 14N15N is selectively photodissociated and 15N atoms deplete onto the dust grain, forming ammonia ices. Our aim is to test this hypothesis. Methods. We targeted three sources (the prestellar core L1544, the protostellar envelope IRAS4A, and the shocked region L1157-B1) with distinct degrees of desorption or sputtering of the ammonia ices. We observed the ammonia isotopologues with the Green Bank Telescope, and we inferred the ammonia 14N/15N via spectral fitting of the observed inversion transitions. Results.15NH3 (1,1) is detected in L1544 and IRAS4A, whilst only upper limits are deduced in L1157-B1. The NH3 isotopic ratio is significantly lower towards the protostar (14N/15N = 210 ± 50) than at the centre of L1544 (14N/15N = 390 ± 40), where it is consistent with the elemental value. We also present the first spatially resolved map of NH3 nitrogen isotopic ratio towards L1544. Conclusions. Our results are in agreement with the hypothesis that ammonia ices are enriched in 15N, leading to a decrease in the 14N/15N ratio when the ices are sublimated back into the gas phase for instance due to the temperature rise in protostellar envelopes. The ammonia 14N/15N value at the centre of L1544 is a factor of 2 lower than that of N2H+, which can be explained if a significant fraction of nitrogen remains in atomic form and if the ammonia formed on the dust grains is released in the gas phase via non-thermal desorption.