Nitrogen Balance Research Articles

Multi-omics analysis of soil microbiota and metabolites in dryland wheat fields under different tillage methods

No-tillage and subsoiling can improve soil aggregate structure and realize a synergistic effect of soil carbon and nitrogen retention compared with deep tillage. This study aimed to investigate the effects of different tillage methods on the microbiome and metabolites in wheat rhizosphere. Results indicated that no significant differences in the diversity of soil bacterial and fungal communities were observed among the tillage methods. Analysis revealed that no-tillage enriched specific genera such as Cryptosporangium, Crossiella, Rhodothermaceae, Leptothrix, Stilbella, Diutina, and Pyrenochaetopsis, while subsoiling was associated with Rubrobacter, Latescibacteraceae, Nitrospira, Rokubacteriales, and Ctenomyces. Deep tillage, on the other hand, showed significant associations with Nocardia, Aeromicrobium, Sphingopyxis, Cordyceps, and Subulicystidium. Metabolomic analysis identified differential metabolites involved in various pathways, including the biosynthesis of plant secondary metabolites, ABC transporters, and starch and sucrose metabolism. Correlation analysis revealed a significant interaction between microorganisms and metabolites in wheat rhizosphere. Bacteria at the genus level exhibited greater associations with differential metabolites. In conclusion, different tillage practices can alter the composition of microbial communities and metabolites in wheat rhizosphere, and their interactions may affect soil fertility and wheat growth.

Characteristics of a heavy metal resistant heterotrophic nitrification–aerobic denitrification bacterium isolated from municipal activated sludge

The heterotrophic nitrification-aerobic denitrification (HNAD) is a new biological denitrification technology, the present study isolated a new HNAD strain named Cupriavidus metallidurans TX6 with heavy metal resistance. The gene expression, electron transport, enzyme activity and nitrogen removal property of strain TX6 were studied with different influencing factors. Strain TX6 has five nitrogen metabolism pathways (NH4+ → NH2OH → NO → NO2− → NH4+ → GOGAT/GDH; NH4+-N → NH2OH → NO → N2O → N2; NH4+ → NH2OH → NO → NO2− → NO3−; NO3− → NO2− → NH4+ → GOGAT/GDH; NO3−→ NO2− → NH4+ → GOGAT/GDH). Nitrogen balance analysis shows that 29 ± 4 mg/L of N was converted to intracellular nitrogen by assimilation and 50 ± 3 mg/L N loss may be attributed to aerobic denitrification. The results provide a theoretical basis for the HAND bacteria application in nitrogen removal from wastewaters containing heavy metals.

Characterization of phosphorus balances in corn silage fields from eight New York dairies

AbstractOptimizing phosphorus (P) application in corn (Zea mays L.) silage production systems to align with crop P requirements while sustaining soil test P (STP) levels can help mitigate environmental risks and enhance farm profitability. The objectives of this study were to characterize P balances of corn silage fields in New York, their drivers, relationships between P balances and field STP and nitrogen (N) balances, as well as the impact of manure application practices on balances. Field‐level balances (supply–uptake) for P and N were derived for 994 field observations across eight dairy farms and 5 years. On average, P balances were low (11 kg P ha−1) with a wide range across farm averages (−11 to 30 kg P ha−1). Across farms, P was applied at higher rates to fields with adequate STP than to lower STP fields, indicating potential opportunities for reallocation of P within farms. Phosphorus balances were positively related to N balances. Manure nutrient utilization indicated that N‐based applications would lead to large positive P balances in all farms. Phosphorus‐based manure applications could cover on average 51% of corn N requirements under current farm manure application practices. This could be increased up to 85% when maximizing the utilization of manure inorganic N. Management alternatives to prevent excessive P balances include improving diet formulation to reduce P excretion, reducing animal density, exporting manure, implementing manure treatment technologies that conserve N and/or remove P, combining appropriate rates of manure and fertilizer, and maximizing manure inorganic N utilization in field applications.

Fulvic Acid Enhances Nitrogen Fixation and Retention in Paddy Soils through Microbial-Coupled Carbon and Nitrogen Cycling.

Fulvic acid, the most soluble and active humic substance, is widely used as an agent to remediate contaminated soils and improve soil fertility. However, the influence of fulvic acid (FA), as a microbial carbon source, on carbon and nitrogen cycles in paddy soils remains elusive. Therefore, to investigate it, an incubation experiment was conducted. Gas analyses indicated that the carbon dioxide and methane emissions were enhanced in FA treatment, which increased up to 94.08-fold and 5.06-fold, respectively. 15N-labeling experiments revealed that nitrogen fixation capability was promoted (1.2-fold) to reduce the carbon and nitrogen imbalance due to fulvic acid amendment. Metagenomic analysis further revealed that gene abundances of degradation of lignin-like compounds, gallate degradation, methanogenesis, nitrogen fixation, and urea hydrolysis increased, while the bacterial ammonia oxidation and anaerobic ammonium oxidation decreased, caused by FA application. Metabolic reconstruction of metagenome-assembled genomes revealed that Azospirillaceae, Methanosarcinaceae, and Bathyarchaeota, with higher abundance in FA treatment, were the key microorganisms to maintain the carbon and nitrogen balance. The metabolic pathways of fulvic acid degradation and coupled nitrogen fixation and retention were constructed. Collectively, our results provided novel insights into the theoretical basis of the use of humic substances for reducing nitrogen fertilization and climate change.

In-Vessel Aerobic Composting of Organic Waste Using Synthetic and Natural Bulking Agents

The escalating growth in municipal solid waste production underscores the imperative need for efficient waste management, especially given that a substantial portion of MSW comprises biodegradable materials suitable for composting. This study investigates the impacts of using a synthetic bulking agent (perforated plastic balls) in conjunction with biochar, a natural bulking agent, on the aerobic composting of kitchen waste. The study aim to evaluate the effectiveness of this combined approach in optimizing the composting process. Four trials, each spanning 30 days, were conducted to assess the effects of different combinations of synthetic and natural bulking agents. The study uses a uniform-size perforated synthetic bulking agent in combination with biochar to enhance the composting process. Results indicate that incorporating the perforated plastic balls (8% by weight) alongside biochar significantly influenced key composting parameters. This approach accelerated the initial rise in temperature to 55°C, enhanced the reduction of total organic carbon, improved total Kjeldahl nitrogen retention, and facilitated the achievement of optimal carbon-nitrogen (C/N) ratios ranging from 19 to 20. Furthermore, the analysis of phosphorus (P) and potassium (K) loss during composting revealed that potassium is more susceptible to leaching than phosphorus due to its higher mobility. The study concludes that the addition of a uniform-size perforated synthetic bulking agent, constituting 8% (by weight), in conjunction with a natural bulking agent, effectively enhances the composting process.

Effect of mineral additives and ammonia-oxidizing bacteria additions on physicochemical properties, nitrogen retention and microbial dynamics during vermicomposting of chicken manure and green waste

Vermicomposting is an effective technology to transform organic wastes into organic fertilizers. However, a large amount of nitrogen will be lost through ammonia (NH3) volatilization during verimicomposting. Herein, we investigated the effects of mineral additives (diatomite, zeolite) and exogenous ammonia-oxidizing bacteria (AOB) (Nitrosomonas europaea, Nitrosospira multiformis) added individually or combinedly on the physicochemical changes, the conversion of nitrogen, and the resident microbial community succession during chicken manure and green waste co-vermicomposting. The results showed that the combined addition of AOB and mineral additives significantly improved vermicompost quality and maturity in terms of humus, carbon/nitrogen ratio, humic acid/fulvic acid ratio and germination index. Compared with the control, jointly adding AOB and mineral additives reduced NH3 emissions by 65.72∼71.05 %, accelerated the conversion of NH4+-N to NO3−-N, increased total nitrogen content by 23.22∼25.21 %. The combination of AOB and mineral additives significantly increased the activities of ammonia monooxygenase, hydroxylamine oxidase, and nitrate oxidoreductase, and enhanced the amount of AOB community. Additionally, the combined addition of AOB and mineral additives increased bacterial richness and diversity, accompanied by increased relative abundances of Luteimonas, Cellvibrio, Saccharimonadales, and Pseudomonas. These microbial shifts were correlated with enhanced lignocellulose degradation, organic phosphate mineralization, and promotion of plant growth. Moreover, vermiompost-based growing media with mineral additives and AOB can significantly promote the growth of purple cabbage as compared to the vermicompost without additives. Overall, the synergistic use of AOB and mineral additives (diatomite, zeolite) was recommended as a favorable approach for reducing nitrogen losses and improving the efficiency of chicken manure and green waste vermicomposting. This study offers a novel approach to mediate nitrogen transformation processes and reduce nitrogen loss.

SiO2 nanoparticles can enhance nitrogen retention and reduce copper resistance genes during aerobic composting of swine manure

SiO2 nanoparticles (SiO2 NPs) are low-cost, environmentally friendly materials with significant potential to remove pollutants from complex environments. In this study, SiO2 NPs were used for the first time as an additive in aerobic composting to enhance nitrogen retention and reduce the expression of copper resistance genes. The addition of 0.5 g kg−1 SiO2 NPs effectively reduced nitrogen loss by 72.33 % by decreasing denitrification genes (nosZ, nirK, and napA) and increasing nitrogen fixation gene (nifH). The dominant factors affecting nitrification and denitrification genes were Firmicutes and C/N ratio. Additionally, SiO2 NPs decreased copper resistance genes by 28.96 % − 37.52 % in compost products. Copper resistance genes decreased most in the treatment with 0.5 g kg−1 SiO2 NPs. In summary, 0.5 g kg−1 SiO2 NPs have the potential to reduce copper resistance genes and enhance nitrogen retention during aerobic composting, which may be used to improve compost quality.

Nanoscale Biochar for Fertilizer Quality Optimization in Waste Composting: Microbial Community Regulation

Conventional composting faces challenges of nitrogen loss, product instability, and limited humic substance formation. This study investigated the effects of nanoscale biochars (nano-BCs) derived from rice straw (nano-RSB) and corn stover (nano-CSB) on manure composting. A randomized design with five treatments was used: control, regular biochars (RSB and CSB), and nano-BCs. Nano-BCs, especially nano-CSB, significantly improved compost maturity and reduced phytotoxicity, achieving a 146.20 % germination index. They increased total nitrogen (55.09–63.64 %) and phosphorus (10.25–12.33 %) retention, reduced NH4+-N loss, and promoted nitrification. Nano-CSB showed the highest final NO3−-N content (8.63 g/kg). Bacterial richness and diversity increased by 25–30 % in nano-BC treatments, with selective enrichment of beneficial species. The unique properties of nano-BCs, including high surface area and microporous structure, improved nutrient retention and compost quality. Nano-BCs offers a promising solution for sustainable waste management and high-quality compost production in agriculture, significantly enhancing nutrient retention and microbial community regulation during composting process.

A Mixture of Summer Legume and Nonlegume Cover Crops Enhances Winter Wheat Yield, Nitrogen Uptake, and Nitrogen Balance

Cover crops protecting soil erosion during the summer fallow in the monsoon weather may enhance dryland winter wheat yield and N relations. We examined the effects of four summer cover crops (soybean (Glycine max L., SB), sudangrass (Sorghum sudanense {Piper} Stapf, SG), soybean and sudangrass mixture (SS), and no cover crop (CK)) and three N fertilization rates (0, 60, and 120 kg N ha−1) on winter wheat yield, quality, and N relations from 2017–2018 to 2020–2021 in the Loess Plateau of China. Cover crop biomass and N accumulation, soil mineral N, and winter wheat yield, protein concentration, and N uptake were greater for SB and SS than other cover crops at most N fertilization rates and years. The N fertilization rate had variable effects on these parameters. Winter wheat aboveground biomass and grain N productivities were greater for CK than other cover crops at all N fertilization rates and years. Nitrogen balance was greater for SS than other cover crops at 60 and 120 kg N ha−1 in all years. The SS with 120 kg N ha−1 can enhance soil mineral N, winter wheat yield and quality, and N balance compared to CK and SG with or without N fertilization rates.

The impact of dissolved organic nitrogen (DON) retention in the vadose zone on nitrogen leaching losses

Leaching of dissolved organic nitrogen (DON) is a significant pathway for nitrogen (N) loss in agricultural ecosystems. The excessive application of N for enhanceing agricultural productivity often results in the leaching of N into groundwater. Yet not well understood, the extent of retention in the vadose zone has critical implications for risk management and remediation strategies. This study aims to advance simulation techniques for modelling the transport process of reactive DON within a heterogeneous vadose zone. Through a combination of laboratory experiments and numerical simulations, the study firstly examines the extent of DON retention in the vadose zone and quantitatively analyse groundwater contamination risk from this kind of accumulation. Our findings indicate that heavy N fertilizer application and high-intensity rainfall events led to elevated contents of DON in the vadose zone and increased DON leaching fluxes into groundwater. Besides, intensifier rainfall reduced the N storage more quickly in scenarios devoid of DON application with higher mineralization rate, while DON slowly mineralized to other forms, largely accumulated in the top layer and migrated deeper with intensifier rainfall after input of urea. In our scenarios, DON accounted for a substantial portion (33–68%) of the total dissolved nitrogen (TDN) leaching fluxes, with exogenous DON content contributing significantly (25–85%) to the overall DON leaching into the aquifer. These results underscore the need for effective strategies to mitigate groundwater contamination risks associated with agricultural N use.

Effect of standard feeding with a high-protein diet on arterial blood gases in patients admitted to the intensive care units: A study protocol for a double-blinded, randomized controlled clinical trial

Critically ill patients admitted to the intensive care units (ICUs) often face numerous challenges, including severe metabolic stress, systemic inflammation, and compromised immune function. Studies have suggested that critically ill patients frequently experience a negative nitrogen balance due to a hypercatabolic state, leading to impaired organ function and muscle wasting, which can cause severe muscle weakness and physical disability for years after discharge. Arterial blood gases (ABG) reflect patients' oxygenation and acid-base status and are crucial indicators of respiratory and metabolic function in critically ill individuals. We aim to address this by conducting a double-blinded, randomized controlled clinical trial to compare the effects of standard feeding with a high-protein diet on ABG in ICU patients. In this double-blinded, randomized controlled clinical trial, we will use block randomization of 80 patients aged between 18 to 65 years old and Patients expected to be hospitalized in the ICU for at least 3 days from Kosar Hospital, Kurdistan, Iran. The intervention group (n=40) will receive a protein diet (consisting of 18.7% protein, 45% carbohydrates, and 35% fat per 1000cc). A control group (n=40) will receive a standard diet (14.4% protein, 54% carbohydrates, and 32.4% fat per 1000cc) for the same duration in addition to usual care. The caloric requirements of each patient will be determined by a nutritionist based on their nutritional status, height, weight, age, and initial diagnosis, utilizing the Harris-Benedict formula. The parameters of ABG, including PO2, PCO2, SAO2, HCO3, BE, and pH, will be assessed. By optimizing protein intake through a high-protein diet, we aim to improve the nutritional status of patients and enhance their overall clinical outcomes. This reassures us of the potential benefits of our study.

Comparison of per kilogram calculation with the nitrogen balance equation in determination of protein needs in cancer patients: A prospective randomized controlled study

Comparison of per kilogram calculation with the nitrogen balance equation in determination of protein needs in cancer patients: A prospective randomized controlled study

Arctic Tundra Plant Dieback Can Alter Surface N2O Fluxes and Interact With Summer Warming to Increase Soil Nitrogen Retention.

In recent years, the arctic tundra has been subject to more frequent stochastic biotic or extreme weather events (causing plant dieback) and warmer summer air temperatures. However, the combined effects of these perturbations on the tundra ecosystem remain uninvestigated. We experimentally simulated plant dieback by cutting vegetation and increased summer air temperatures (ca. +2°C) by using open-top chambers (OTCs) in an arctic heath tundra, West Greenland. We quantified surface greenhouse gas fluxes, measured soil gross N transformation rates, and investigated all ecosystem compartments (plants, soils, microbial biomass) to utilize or retain nitrogen (N) upon application of stable N-15 isotope tracer. Measurements from three growing seasons showed an immediate increase in surface CH4 and N2O uptake after the plant dieback. With time, surface N2O fluxes alternated between emission and uptake, and rates in both directions were occasionally affected, which was primarily driven by soil temperatures and soil moisture conditions. Four years after plant dieback, deciduous shrubs recovered their biomass but retained significantly lower amounts of 15N, suggesting the reduced capacity of deciduous shrubs to utilize and retain N. Among four plant functional groups, summer warming only increased the biomass of deciduous shrubs and their 15N retention, while following plant dieback deciduous shrubs showed no response to warming. This suggests that deciduous shrubs may not always benefit from climate warming over other functional groups when considering plant dieback events. Soil gross N mineralization (~ -50%) and nitrification rates (~ -70%) significantly decreased under both ambient and warmed conditions, while only under warmed conditions immobilization of NO3 - significantly increased (~ +1900%). This explains that plant dieback enhanced N retention in microbial biomass and thus bulk soils under warmed conditions. This study underscores the need to consider plant dieback events alongside summer warming to better predict future ecosystem-climate feedback.

Gross hematuria and congestive heart failure – two sides of the same coin

Poststreptococcal glomerulonephritis (PSGN) is an immune-mediated disease following infection with nephritogenic strains of group A β-hemolytic Streptococcus (GAS), affecting children aged of 2 to 10. We report 2 different presentations of PSGN from “Grigore Alexandrescu” Hospital. Case 1: A 5 years old girl was admitted for gross hematuria. Investigations revealed: anemia, inflammatory syndrome, mild nitrogen retention syndrome, elevated ASO and low levels of serum C3, nephritic-range proteinuria and severe hematuria. she received antibiotic treatment with initial improvement. A relapse occurred in one week, a second course of antibiotic and corticosteroids was necessary. Case 2: A 15-year-old girl was admitted for acute cardiac failure, hypertension and oliguria. Investigations revealed anemia, nitrogen retention, dyslipidemia, inflammatory syndrome, high ASO titers, low serum C3, microscopic hematuria, nephrotic-range proteinuria. She had fluid build-up in both lungs and pericardium. The diagnosis was PSGN and congestive heart failure (volume overload). She received antibiotics, diuretics and ACE inhibitors. PSGN is re-emerging in pediatric practice due to the resurgence of streptococcal infections within children's communities. The clinical presentation might be highly variable, ranging from hematuria to heart failure. Clinicians should be aware and actively consider this diagnosis.

A comparison of animal and plant-based proteins from an economic, environmental, and nutritional perspective in the Republic of Ireland

CONTEXTProtein is a central component of health and nutrition. The current protein production system is unlikely to sustainably meet the growing global demand for protein. Therefore, alternative sources of protein must be considered. OBJECTIVEThis study uniquely compares animal-based (milk, beef meat, sheep meat) and plant-based (cereals and legumes) protein production in terms of land usage. The comparison is carried out across a suite of economic, environmental, and nutritional metrics. As land use decisions are taken at the farm level, the analysis adopts a farm gate approach. Focusing on the supply side, consumption is not considered in the analysis. METHODSEconomic performance is measured through the gross and net margins. Environmental performance is evaluated through farm-level greenhouse gas (GHG) emissions and nutrient (nitrogen and phosphorus) balances. Nutritional performance is measured through the gross protein yield, the protein yield corrected for digestibility and land-use efficiency, i.e., the land needed to generate one kg of (digestible) protein. Results are expressed per hectare and per 100 g of gross and digestible protein to allow for a holistic comparison. The analysis focuses on the Republic of Ireland, a relevant country given the importance of the strong agricultural export focus, the dominance of the livestock sector and the country's ambitious environmental emission reduction targets. RESULTS AND CONCLUSIONSFindings indicate that, on a per hectare basis, milk production on dairy farms has the strongest economic performance and highest GHG emissions amongst the products considered. Crops' gross and net margins are less than half that of dairy farms, but they also show the strongest environmental performance generally. Cereals and legumes have the best nutritional performance, from a protein perspective, whereas sheep meat production returned the lowest gross and digestible protein yields per hectare. Arable crops also show the lowest GHG emissions and nutrient balances on a per unit of protein basis. SIGNIFICANCELand-use policies need to be designed holistically, given the complexity of the agricultural sector. Agricultural policy design currently focuses on income support and on the environmental impact of the agricultural sector, but farmers' livelihood and food and protein security need to be safeguarded. Diversifying agricultural production and increasing plant-based protein production in Ireland, a country with a livestock-focused agricultural sector, could contribute to achieving the climate change targets of the country, provided the necessary policy levers are in place.

Nitrate removal by a novel aerobic denitrifying Pelomonas puraquae WJ1 in oligotrophic condition: Performance and carbon source metabolism

Reducing nitrate contamination in drinking water has become a critical issue in urban water resource management. Here a novel oligotrophic aerobic denitrifying bacterium, Pelomonas puraquae WJ1, was isolated and purified from artificial lake sediments. For the first time, excellent aerobic denitrification capabilities were demonstrated. At a carbon-to‑nitrogen ratio of 5.0, strain WJ1 achieved 100.0 % nitrate removal and 84.92 % total nitrogen removal within 24 h, with no nitrite accumulation. PCR amplification and sequencing confirmed the presence of the denitrification genes napA, nirS, and nosZ in the strain. The nitrogen balance demonstrated that approximately 74.95 % of the initial nitrogen was eliminated as gaseous products under aerobic conditions. Furthermore, carbon balance analysis showed that most electron donors from strain WJ1 were directed towards oxygen, with limited availability for nitrate reduction. A combination of bio-ECO analysis and network modeling indicated that strain WJ1 has robust metabolic capabilities for diverse carbon sources and exhibits high adaptability to complex carbon environments. Overall, Pelomonas puraquae WJ1 removed approximately 45.89 % of the nitrates in raw water, demonstrating significant potential for practical applications in oligotrophic denitrification.

Effect of replacing Tifton 85 hay with Moringa hay (Moringa oleifera L.) on the nutrient metabolism, metabolic profile, and water balance of sheep.

This study aimed to evaluate the effect of replacing Tifton 85 hay (TH) with Moringa hay (MH) on the intake, apparent digestibility, ingestive behaviour, rumen parameters, serum attributes, nitrogen balance, water balance, and urinary attributes of sheep. Thus, 5 rams, ½ Dorper + ½ Santa Inês, that were 12 ± 4 months of age with an initial body weight of 32.8 ± 2.6kg were distributed in metabolic cages in a Latin square design. The experiment lasted 85 days and was divided into five 17-day periods. The animals received rations with increasing replacement (0, 100, 200, 300, or 400g/kg of dry matter in the total diet) of TH for MH. The forage: concentrate ratio of the diets was 40:60. Replacing TH with MH reduced (P < 0.05) the intake of organic matter, crude protein, neutral detergent fibre (NDFap), and total digestible nutrients by sheep. The apparent digestibility of NDFap and the feeding and rumination efficiencies of NDFap were reduced (P < 0.05) when MH replaced TH in the animals' diet. This replacement did not influence (P > 0.05) serum urea, total protein, creatinine, or aspartate aminotransferase in sheep. Replacing TH with MH decreased water intake and excretion (P < 0.05). In addition, nitrogen excretion via urine, urinary creatinine, and nitrogen absorption decreased (P < 0.05) when TH was replaced with MH. However, there was an increase in the sheep's nitrogen retention and urine pH. We recommend replacing 30% TH with MH in the diet of lambs because it does not compromise nutrient metabolism.

Characterisation of Pseudomonas mosselii H6 for aerobic denitrification: stoichiometry and reaction kinetics

The application of aerobic denitrifying bacteria in biological nitrogen removal has been of great interest. However, the mechanism of nitrogen conversion by aerobic denitrifying bacteria is unclear due to the lack of stoichiometry and kinetic studies. Therefore, this study aimed to investigate the stoichiometry and kinetics of aerobic denitrification using Pseudomonas mosselii H6 as a model strain. The results showed that the stoichiometric equations of strain H6 under different nitrogen source conditions were obtained by nitrogen balance analysis; the concentrations of different limiting substrates were set and combined with the multi-substrate Monod kinetic equation to fit the half-saturation constants of COD, ammonia, nitrate and nitrite nitrogen for strain H6, which were 230.1008, 25.3435, 4.1009 and 23.4601 mg/L, respectively; based on the model of “two-step denitrification”, the numerical simulation of the growth and aerobic denitrification of strain H6 under different limiting substrate concentrations was carried out by using AQUASIM software to test the validity of stoichiometric coefficients and kinetic constants and perfect fitting results were obtained. These parameters will help to simulate the growth and denitrification performance of aerobic denitrifying bacteria and provide an experimental basis for further quantitatively elucidating the mechanism of action in the aerobic denitrification process.

Nitrogen fertiliser application rate to temperate mid-season grass: Digestion, nitrogen balance and rumen microbiota in beef cattle, and rumen fermentation and methane production in vitro

Nitrogen (N) excretion by cattle, particularly urinary N, can have detrimental environmental impacts on air and water quality, and contributes to greenhouse gas emissions. The effects of increasing the application rate of inorganic N fertiliser from 15 (N15) to 80 (N80) kg/ha per cut to Lolium perenne dominant swards in summer, on intake, rumen fermentation, rumen microbial populations, apparent total-tract digestibility and N-balance in beef cattle, and in vitro fermentation and methane output, were studied. Sixteen suckler-bred Charolais steers, used in a randomised block design experiment, were offered fresh grass mechanically harvested 21-d after N fertiliser application. Similar grass was incubated in an eight-vessel in vitro RUSITEC system. Grass crude protein concentration was 50 g/kg dry matter (DM) higher for N80 compared to N15. There was no difference in grass DM intake between treatments. Rumen fermentation variables did not differ between treatments, except for the molar proportion of propionate, which was greater for N80 than N15. Gross microbial community structure in the rumen was not significantly altered by inorganic N fertiliser application rate. The relative abundance of individual genera Lachnospiraceae_NK3A320_group and Ruminococcaceae_NK4A214_group, and Acetitomaculum were significantly lower at the higher N application rate. Mean plasma urea concentration was greater for N80 compared to N15. In vivo digestibility of DM, organic matter, neutral detergent fibre and acid detergent fibre was unaffected by fertiliser N application rate. Nitrogen intake was 75 g/d greater, and urinary and faecal N excretion were 20 and 5 g/d greater, respectively, for N80 than N15. The quantity of N retained and N use efficiency was greater for N80 compared to N15. In vitro NH3 concentration was greater for N80 than N15, whereas other rumen fermentation variables, and in vitro methane and total gas output, did not differ between treatments. Reducing the inorganic N fertiliser rate applied to mid-season temperate grass reduced N excretion from beef cattle, which is environmentally beneficial, with no effect on in vitro methane production.

Influence of crop rotation, the treatment of crop residues, and the application of nitrogen fertilizers on soil properties and maize yield

AbstractThis inquiry is aimed at discerning the impact of various agricultural practices, such as crop rotation, the incorporation of plant residues, and the application of mineral fertilizers, on soil health and crop productivity, notably focusing on maize production. Cultivation included maize (Zea mays), velvet beans (Mucuna pruriens), soybeans (Glycine max), and vetch (Vicia sativa). After harvest, maize seeds were sown across all 48 plots to evaluate the influence of preceding crop rotation on soil properties and maize yield. Hypotheses posited in the study suggested that crop rotation, nitrogen fertilizer application, and the incorporation of crop residues positively impact soil fertility. The study further argues that the utilization of cover crops in crop rotation aids in nitrogen retention within the soil and enhances yield. The results were processed utilizing a two‐way analysis of variance (ANOVA) with interaction and post hoc comparisons. The findings confirm that crop rotation, nitrogen fertilizer application, and incorporation of crop residues influence soil fertility. The study found that crop rotation and nitrogen fertilizers have a significant impact on soil properties. Crop rotations such as “velvet beans‐maize” and “soybeans‐maize” increased soil fertility by 10%–15% compared to crop rotations of “vetch‐maize” and maize monocultures. Nitrogen fertilizers increased the total nitrogen content in the soil by 5%–10% in both years. Crop residues also positively affected soil properties, increasing pH and total nitrogen by 1%–5%. The study demonstrates that crop rotation, nitrogen fertilizers, and crop residues can be effective management methods for improving soil fertility and reducing the risk of nitrate leaching.