Search Results (16)

The soil nitrification rate is significantly affected by plant species, and it is also modulated by different nitrogen levels in the soil. There are a wide range of plant species with the capacity to produce biological nitrification inhibitors (hereafter referred to as BNI species). The preliminary results of this study report the influence of three different plant species on the nitrification rates under soil supply with three (0 mM, 3.5 mM, and 7.0 mM) nitrogen levels. The aim was to evaluate the potential of hemp, ryegrass, and sorghum in mitigating nitrification, in order to define a sustainable strategy for improving the nitrogen use efficiency by crops and to limit the nitrogen loss from agroecosystems. Leaf gas exchange measurements were also carried out in this study. Photosynthesis was only affected by nitrogen supply in hemp, resulting in a reduction in CO₂ assimilation at nitrogen doses higher than the plant’s requirements. Ryegrass devotes more reductive power towards leaf nitrogen assimilation than sorghum and hemp do. The greatest variation in nitrification rate in response to N was observed in soil cultivated with hemp (which also showed the highest potential nitrification rate), followed by sorghum and ryegrass. We speculate that this occurred because the greater seed sowing density for ryegrass ensured a greater quantity in the soil of molecules acting on nitrification compared to sorghum and hemp, with these latter being sown at lower densities. Our results suggest that sorghum and ryegrass might directly affect nitrification by BNI molecules, whereas hemp might indirectly mitigate nitrification through the nitrogen uptake. However, further research is needed to evaluate the effects exerted by the studied plant species on nitrification rates. Full article

Nitrogen (N) cycling in agroecosystems is a complex process regulated by both biological and agronomic factors, with ammonia-oxidizing archaea (AOA) and bacteria (AOB) playing pivotal roles in nitrification. Despite extensive fertilizer applications to achieve maximum crop yields, nitrogen use efficiency (NUE) remains less than ideal, with substantial losses contributing to environmental degradation. This review synthesizes current knowledge on plant-mediated and fertilization-induced shifts in ammonia-oxidizer communities and their implications on nitrogen cycling. We highlight the differential ecological niches of AOA and AOB, emphasizing their responses to plant community composition, root exudates, and allelopathic compounds. Fertilization regimes of inorganic nitrogen inputs and biological nitrification inhibition (BNI) are examined in the context of microbial adaptation and ammonia tolerance. Our review highlights the need for integrated nitrogen management strategies comprising optimized fertilization timing, nitrification inhibitors, and plant–microbe interactions in order to optimize NUE and mitigate nitrogen losses. Future research directions must involve applications of metagenomic and isotopic tracing techniques to unravel the mechanistic AOA and AOB pathways that are involved in regulating these dynamics. An improved understanding of these microbial interactions will inform the creation of more sustainable agricultural systems that aim to optimize nitrogen retention and reduce environmental footprint. Full article

Plant invasions play a significant role in global environmental change. Traditionally, it was believed that invasive plants absorb and utilize nitrogen (N) more efficiently than native plants by adjusting their preferred N forms in accordance with the dominant N forms present in the soil. More recently, invasive plants are now understood to optimize their N acquisition by directly mediating soil N transformations. This review highlights how exotic species optimize their nitrogen acquisition by influencing soil nitrogen dynamics based on their preferred nitrogen forms, and the various mechanisms, including biological nitrification inhibitor (BNI) release, pH alterations, and changes in nutrient stoichiometry (carbon to nitrogen ratio), that regulate the soil nitrogen dynamics of exotic plants. Generally, invasive plants accelerate soil gross nitrogen transformations to maintain a high supply of NH₄⁺ and NO₃⁻ in nitrogen-rich ecosystems irrespective of their preference. However, they tend to minimize nitrogen losses to enhance nitrogen availability in nitrogen-poor ecosystems, where, in such situations, plants with different nitrogen preferences usually affect different nitrogen transformation processes. Therefore, a comprehensive understanding requires more situ data on the interactions between invasive plant species’ preferential N form uptake and the characteristics of soil N transformations. Understanding the combination of these processes is essential to elucidate how exotic plants optimize nitrogen use efficiency (NUE) and minimize nitrogen losses through denitrification, leaching, or runoff, which are considered critical for the success of invasive plant species. This review also highlights some of the most recent discoveries in the responses of invasive plants to the different forms and amounts of N and how plants affect soil N transformations to optimize their N acquisition, emphasizing the significance of how plant–soil interactions potentially influence soil N dynamics. Full article

Nitrogen (N) fertilizer incorporation of efficiency enhancer is a well-established practice aiming at reducing N loss while enhancing crop yield. However, the effect of different kinds of fertilizer efficiency enhancer on N use efficiency (NUE) and gas loss are rarely compared and poorly comprehended. Here, we conducted a field experiment involving the combination of urease and nitrification inhibitor (NI), the biological inhibitor eugenol (DE) and the bioploymer poly-glutamic acid (PG) and their combinations (NI + PG, NI + DE, PG + DE) to evaluate their effects on crop yield, NUE, NH3 volatilization and greenhouse gas emissions (GHGs). Results indicated that NI, DE, PG and their combinations significantly enhanced the crop yield, N uptake and NUE. NI, DE and PG are all effective in reducing NH₃ volatilization and N₂O emission, averagely decreased by 11.13%, 6.83%, 8.29%, respectively, and by 11.15%, 4.32%, 8.35%, respectively, while have no significant effects on CO₂-C and CH₄-C fluxes, except PG significantly increases CO₂-C emission and thus global warming potential. The combination of these three efficiency enhancers has no multiply effect on maize yield, NUE and gas loss. These findings help to screen the fertilizer efficiency enhancer that can be more effectively utilized in agricultural practices and contribute to their application strategies within agricultural systems. Full article

Agro-industrial residues have transitions from being an environmental problem to being a cost-effective source of biopolymers and value-added chemicals. However, the efficient extraction of the desired products from these residues requires pretreatments. Fungal biorefinery is a fascinating approach for the biotransformation of raw materials into multiple products in a single batch. In this study, the ability of Trichoderma asperellum R to convert fruit scrap and green waste into value-added chemicals was tested in solid-state and in nonsterile conditions. A solid-state fermentation protocol for a tray bioreactor was developed using spawn as the inoculum for nonsterile substrates. T. asperellum R drove the fermentation of both substrates, shaping the metabolites that were enriched in the secondary plant metabolites. Strain R showed cellulase activity only when inoculated on fruit scraps, resulting in increased amounts of polysaccharides in the crude extract. This extract was also enriched in vanillic acid and limonoid, which are intriguing compounds due to the increasing interest in their potential as biological nitrification inhibitors or food additives. Finally, trimethoxybenzaldehyde, an interesting chemical building block, was identified in the extracts of the Trichoderma-guided fermentation. The overall results showed that the application of T. asperellum R has potential as a driver to facilitate the extraction of bioactive substances from nonsterile recalcitrant substrates. Full article

To meet the growing population’s demand for food, humans have introduced large amounts of nitrogen fertilizers into agricultural systems, resulting in highly nitrified environments in most farmland soils. In highly nitrified environments, the application of nitrogen fertilizer easily leads to the formation of nitrate (NO₃⁻) and subsequent leaching, resulting in very low utilization rates. Moreover, nitrogen loss can cause harm to both the environment and human health, making it necessary to inhibit the nitrification process. Nitrification inhibitors can suppress nitrification, and inhibitors derived biologically from plant roots are gaining attention due to their low cost and environmental friendliness. Sorghum, as a crop capable of growing in arid environments, holds economic value and also possesses the ability to secrete biological nitrification inhibitors. This article utilizes sorghum as a case study to review different types of BNIs (MHPP, sorgoleone, and sakuranetin), their mechanisms of inhibition, and influencing factors. This article summarizes the contributions of these inhibitors in reducing N₂O emissions and increasing food production, while also providing insight into future research directions for sorghum’s biological nitrification inhibitors in terms of agricultural production efficiency. BNIs are expected to play an important role in improving agricultural production and reducing environmental pollution. Full article

Arable soils significantly contribute to atmosphere pollution through N₂O emissions due to the massive use of N-based fertilizers and soil managements. N₂O formation in the soil occurs mainly through nitrification and denitrification processes, which are influenced by soil moisture, temperature, oxygen concentration, pH, and the amount of available organic carbon and nitrogen. This review synthetically presents the mechanisms of N₂O formation and emission in arable land and some of the current strategies to improve crop nutrient use efficiency. Biological nitrification inhibitor-based agronomic strategies are also presented as future prospects for the sustainable management of crops, which is missing in most of the reviews. Full article

This study aimed to investigate the effects of a biological nitrification inhibitor on nitrous oxide emission and rice yield quality in paddy soils and its effects on denitrifying the bacteria of nosZ, nirK, and nirS types. Two treatments were performed: (1) using a local conventional fertilizer as the control CK; (2) using the partial application of a conventional fertilizer + biological nitrification inhibitor as SW. N₂O emission was measured using gas chromatography; qPCR amplification was performed using primers for the targeted functional genes, nosZ, nirS, and nirK, and denitrifying functional gene abundance and denitrifying microbial community structure were analyzed using fluorescence quantification and high–throughput sequencing, respectively. The results reveal that the biological nitrification inhibitor resulted in a 41.83% reduction in N₂O, relative to the normal fertilizer treatment. Meanwhile, rice yield increased by 15.45% and related quality indexes were also improved. This can promote the reproduction of bacteria with the nosZ gene while inhibiting the growth of bacteria with nirS and nirK genes. The core bacteria, Nitrosospira, Rhodanobacter, Bradyrhizobium, Tardiphaga, Rhodopseudomonas, and Paracoccus, positively correlated with N₂O emissions, while core bacteria Azospirillum, Burkholderia, and Mesorhizobium negatively correlated with N₂O emissions. Therefore, the application of a biological nitrification inhibitor could be an effective measure to promote rice yield and quality, reduce N₂O emissions, and affect key denitrifying bacteria. Full article

COD is an arbitrary indicator of the content of organic and inorganic compounds in wastewater. The aim of this research was to determine the effect of COD of industrial wastewater on the nitrification process. This research covered wastewater from acrylonitrile and styrene–butadiene rubbers, emulsifiers, polyvinyl acetate, styrene, solvents (butyl acetate, ethyl acetate) and owipian^® (self-extinguishing polystyrene intended for expansion) production. The volume of the analyzed wastewater reflected the active sludge load in the real biological treatment system. This research was carried out by the method of short-term tests. The nitrification process was inhibited to the greatest extent by wastewater from the production of acrylonitrile (approx. 51%) and styrene–butadiene (approx. 60%) rubbers. In these wastewaters, nitrification inhibition occurred due to the high COD load and the presence of inhibitors. Four-fold dilution of the samples resulted in a two-fold reduction in the inhibition of nitrification. On the other hand, in the wastewater from the production of emulsifiers and polyvinyl acetate, a two-fold reduction in COD (to the values of 226.4 mgO₂·dm⁻³ and 329.8 mgO₂·dm⁻³, respectively) resulted in a significant decrease in nitrification inhibition. Wastewater from the production of styrene, solvents (butyl acetate, ethyl acetate) and owipian^® inhibited nitrification under the influence of strong inhibitors. Lowering the COD value of these wastewaters did not significantly reduce the inhibition of nitrification. Full article

Nitrogen (N) is an important nutrient for the growth and development of rice. The application of N fertilizer has become one of the inevitable ways to increase rice yield due to insufficient soil N content. However, in order to achieve stable and high yield, farmers usually increase N fertilizer input without hesitation, resulting in a series of problems such as environmental pollution, energy waste and low production efficiency. For sustainable agriculture, improving the nitrogen use efficiency (NUE) to decrease N fertilizer input is imperative. In the present review, we firstly demonstrate the role of N in mediating root architecture, photosynthesis, metabolic balance, and yield components in rice. Furthermore, we further summarize the current agronomic practices for enhancing rice NUE, including balanced fertilization, the use of nitrification inhibitors and slow-release N fertilizers, the split application of N fertilizer, root zone fertilization, and so on. Finally, we discuss the recent advances of N efficiency-related genes with potential breeding value. These genes will contribute to improving the N uptake, maintain the N metabolism balance, and enhance the NUE, thereby breeding new varieties against low N tolerance to improve the rice yield and quality. Moreover, N-efficient varieties also need combine with precise N fertilizer management and advanced cultivation techniques to realize the maximum exploitation of their biological potential. Full article

Conventional biological nutrient removal processes in municipal wastewater treatment plants are energy-consuming, with oxygen supply accounting for 45–75% of the energy expenditure. Many recent studies examined the implications of the anammox process in sidestream wastewater treatment to reduce energy consumption, however, the process did not successfully remove nitrogen in mainstream wastewater treatment with relatively low ammonia concentrations. In this study, blue light was applied as an inhibitor of nitrite-oxidizing bacteria (NOB) in a photo sequencing batch reactor (PSBR) containing raw wastewater. This simulated a biological nitrogen removal system for the investigation of its application potential in nitrite accumulation and nitrogen removal. It was found that blue light illumination effectively inhibited NOB rather than ammonia-oxidizing bacteria due to their different sensitivity to light, resulting in partial nitrification. It was also observed that the NOB inhibition rates were affected by other operational parameters like mixed liquor suspended solids (MLSS) concentration and sludge retention time (SRT). According to the obtained results, it was concluded that the process efficiency of partial nitrification and anammox (PN/A) could be significantly enhanced by blue light illumination with appropriate MLSS concentration and SRT conditions. Full article

Agricultural sites contribute extensively to atmospheric emissions of climate-altering gases such as nitrous oxide. Several strategies have been considered to mitigate the impact of agriculture on climate, among these the utilization of fertilizers added with nitrification inhibitors such as DMPP (3,4-dimethylpyrazole phosphate) may represent a suitable solution. DMPP inhibits the growth and activity of ammonia-oxidizing microorganisms, particularly the ammonia-oxidizing bacteria, which are involved in N₂O production. At present, little information is available on the effects of DMPP on the catabolic diversity of soil microbial community. In this study, the N₂O emission by soil was performed by using the static chamber technique. The biological determinations of the microbial biomass carbon and the catabolic profile were assessed by measuring the substrate-induced respiration during the entire growing season of a potato crop under two nitrogen treatments: fertilization with and without DMPP. Our results did not show a clear mitigation of N₂O emission by DMPP, even if a tendency to lower N₂O fluxes in DMPP plots occurred when soil temperatures were lower than 20 °C. Conversely, DMPP deeply affected the microbial biomass and the catabolism of soil microorganisms, exerting a negative effect when it accumulated in excessive doses in the soil, limiting the growth and the capacity of soil microorganism communities to use different substrates. Full article

Soil nitrification (microbial oxidation of ammonium to nitrate) can lead to nitrogen leaching and environmental pollution. A number of plant species are able to suppress soil nitrifiers by exuding inhibitors from roots, a process called biological nitrification inhibition (BNI). However, the BNI activity of perennial grasses in the nutrient-poor soils of Australia and the effects of BNI activity on nitrifying microbes in the rhizosphere microbiome have not been well studied. Here we evaluated the BNI capacity of bermudagrass (Cynodon dactylon L.), St. Augustinegrass (Stenotaphrum secundatum (Walt.) Kuntze), saltwater couch (Sporobolus virginicus), seashore paspalum (Paspalum vaginatum Swartz.), and kikuyu grass (Pennisetum clandestinum) compared with the known positive control, koronivia grass (Brachiaria humidicola). The microbial communities were analysed by sequencing 16S rRNA genes. St. Augustinegrass and bermudagrass showed high BNI activity, about 80 to 90% of koronivia grass. All the three grasses with stronger BNI capacities suppressed the populations of Nitrospira in the rhizosphere, a bacteria genus with a nitrite-oxidizing function, but not all of the potential ammonia-oxidizing archaea. The rhizosphere of saltwater couch and seashore paspalum exerted a weak recruitment effect on the soil microbiome. Our results demonstrate that BNI activity of perennial grasses played a vital role in modulating nitrification-associated microbial populations. Full article

Aims: Biological nitrification inhibition (BNI) has been reported as an emerging technology to control soil nitrifier activity for effective N-utilization in cropping systems. Brachiaria have been reported to suppress nitrifier populations by releasing nitrification inhibitors from roots through exudation. Substantial BNI activity has been reported to be present in the root tissues of Brachiaria grasses; however, BNI contribution, such as root turnover, has not been addressed in previous studies. The present study aimed to clarify the contribution of root turnover on BNI under Brachiaria cultivations and its impact on nitrifier populations. Methods: We monitored root growth, changes in ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) numbers, nitrification rate, and available nitrogen (N) content under seven germplasm lines of Brachiaria, for 18 months with seasonal profile sampling. Results: Brachiaria cultivation increased soil NH₄⁺-N, available N, and total soil carbon levels. Though we did not find any correlation between the changes in AOB populations and potential nitrification, the potential nitrification rate decreased when AOA populations decreased. Multiple regression analysis indicated that BNI substances from root tissue turnover had a significant contribution to the BNI function in the field. Conclusion Results indicated that the inhibitory effect of BNI was mostly evident in AOA, and not in AOB, in this study. Brachiaria cvs. ‘Marandu’, ‘Mulato’, and ‘Tupy’ had the most substantial BNI effect among the seven cultivars evaluated. The estimated total BNI activities and available N content of root tissue explained the observed nitrification inhibition. In conclusion, the release of BNI substances through plant decomposition contributes to the decrease in the abundance of AOA, and thus the inhibition of nitrification under Brachiaria cultivation. Full article

The article evaluates the effectiveness of the removal of organic pollutants—nitrogen and phosphorus—from household sewage in a hybrid bioreactor with a submerged fixed bed. The experiment was carried out in two exploitation variants that were both conducted in a laboratory model of the hybrid bioreactor: (I) cycles of 120 min of aeration and 60 min of no aeration with a constant sewage dosage, and (II) cycles 60 min of aeration and 60 min of no aeration, with a periodic sewage dosage in the no-aeration phase. The experiment was carried out on real sewage primarily treated in a septic tank. The amount of pollution removal was calculated and compared with the mandatory standards according to Polish law. Moreover, the susceptibility of the sewage to the biological treatment, nitrification, and denitrification activity was determined. The research shows a higher effectiveness for the 60/60 model in comparison to the 120/60 model. High operation efficiency was observed regarding the removal of organic pollution and nitrate nitrogen. The tested structure showed very low nitrification activity combined with intense denitrification. These processes were observed in the 60/60 variant. The structure was often overloaded with the nitrate nitrogen, which was considered to be the nitrification process inhibitor. It was suggested that phosphorus was also removed by the denitrifying bacteria. Full article