Variation In Nitrogen Content Research Articles

Effect of Humic Acid and the Level of Nano and Conventional Nitrogen on the Available and Absorbed Nitrogen Element and the Potato Yield

A field experiment was carried out during the fall season of 2021 at the research station of the University of Anbar - College of Agriculture, to find out the effect of humic acid and the level of nano and conventional nitrogen in the prepared and absorbed nitrogen element and the yield of potato cultivar Rivera, the experiment included two factors: the two sources of nitrogen and their levels, represented by the traditional nitrogen NT1, NT2 at the level of 150 and 300 kg N ha-1 in the form of (urea fertilizer) and the nano-nitrogen, Nn1, Nn2, Nn3 at level 15, 30 and 45 kg N ha-1 sequentially in addition to the control treatment. The second factor was the addition of humic acid H1 at the level of 100 kg ha-1 in addition to the control treatment (without addition) and according to the RCBD randomized complete block design with three replications. The results were statistically analyzed and the means of the coefficients were compared at the 0.05 probability level to test for the least significant difference. The results of the study showed the following: The treatments achieved a remarkable variation in nitrogen content in the vegetative part and tubers, and the interaction coefficients between humic acid and urea achieved the highest nitrogen content in the vegetative part and tubers, as well as the total nitrogen uptake. While the Nn3H1 treatment achieved the highest value of the marketing outcome. The availability of ammonium and nitrate in the soil increased with the increase in fertilization levels for the two fertilizer exporters, and the highest availability was achieved in the presence of humic acid. There was a significant effect of adding humic acid on (AE), which amounted to 59.0% compared to 49.0%, and the lowest decrease in field efficiency was with conventional nitrogen fertilizer treatments compared to the highest field efficiency achieved with nano-nitrogen addition treatments. While the highest value of the field efficiency when treating the interference was Nn3H1. The availability of ammonium and nitrate in the soil increased with the increase in fertilization levels for the two fertilizer exporters, and the highest availability was achieved in the presence of humic acid. There was a significant effect of adding humic acid on AE, which amounted to 59.0% compared to 49.0%, and the lowest decrease in field efficiency was with conventional nitrogen fertilizer treatments compared to the highest field efficiency achieved with nano-nitrogen addition treatments. While the highest value of the field efficiency when treating the interference was Nn3H1. The availability of ammonium and nitrate in the soil increased with the increase in fertilization levels for the two fertilizer exporters, and the highest availability was achieved in the presence of humic acid. There was a significant effect of adding humic acid on (AE), which amounted to 59.0% compared to 49.0%, and the lowest decrease in field efficiency was with conventional nitrogen fertilizer treatments compared to the highest field efficiency achieved with nano-nitrogen addition treatments. While the highest value of the field efficiency when treating the interference was Nn3H1. The addition of humic acid achieved an efficient nitrogen recovery NUE amounted to 60.13% compared to 44.45%. The treatment of adding nano-nitrogen Nn1, Nn2 and Nn3 recorded recovery efficiency of the element amounted to 82.47, 80.14 and 77.89% respectively, and was superior to the traditional fertilization treatments NT1, NT2, which amounted to 39.72, 29.81% respectively, while the dual interaction treatments achieved the highest recovery efficiency of the element which reached to the treatments of the nano-source Nn1H1, Nn2H1, Nn3H1 (95.25, 92.08 and 88.71%) sequentially. Compared with the levels of the traditional source NT1H1, NT2H1 (45.35 and 31.95%), respectively.

Modeling the effect of the submerged zone on nitrogen removal efficiency of a bioretention system under dry-wet alterations

Bioretention systems are effective stormwater treatment systems. Many studies have been conducted on the nitrogen regulation effects of bioretention systems. However, few studies had investigated the variation of nitrogen concentration in the submerged zone during dry periods and evaluated the effect of the submerged zone on nitrogen removal efficiency under dry-wet alterations. Furthermore, existing models cannot fully consider the impact of the submerged zone on nitrogen removal. This paper presents the validation, prediction uncertainty, parameter sensitivity analysis, and scenario simulations with different submerged zone depths of a proposed model. We conducted 13 consecutive rainfall events for model validation under dry-wet alternations in a mesocosm bioretention system with a submerged zone. The collected data mainly includes outflow rates, outflow nitrogen concentrations (NH4-N, NO3-N, and TN) in wet periods, and submerged zone nitrogen concentrations (NH4-N, NO3-N, and TN) in dry periods. The results show that (1) the Nash efficiency coefficients in the wet and dry periods were all above 0.5 during calibration and validation phases; (2) the prediction uncertainty of outflow/submerged zone nitrogen concentration (NH4-N, NO3-N, and TN) can be significantly reduced by using NSE values of the wet and dry periods as likelihood objective functions than only using NSE values of the wet periods; (3) the sensitivity analysis shows that outflow nitrogen concentrations (NH4-N, NO3-N, or TN) are sensitive to most of nitrogen module parameters in the submerged zone; (4) in the long-term dry-wet alterations simulation, the increase of submerged zone depth can improve the annual average nitrogen removal rate, while it does not always improve nitrogen removal rates in single rainfall event. If a rainfall event with a short antecedent dry period (<1.5 d) and the inflow nitrogen concentration in the current event is less than that in the previous event, the increase of the submerged zone depth will even reduce the nitrogen removal rate.

Effects of fungal agents and biochar on odor emissions and microbial community dynamics during in-situ treatment of food waste

The effects of the co-addition of fungal agents and biochar on physicochemical properties, odor emissions, microbial community structure, and metabolic functions were investigated during the in-situ treatment of food waste. The combined addition of fungal agents and biochar decreased cumulative NH3, H2S, and VOCs emissions by 69.37%, 67.50%, and 52.02%, respectively. The predominant phyla throughout the process were Firmicutes, Actinobacteria, Cyanobacteria, and Proteobacteria. Combined treatment significantly impacted the conversion and release of nitrogen from the perspective of the variation of nitrogen content between different forms. FAPROTAX analysis revealed that the combined application of fungal agents and biochar could effectively inhibit nitrite ammonification and reduce the emission of odorous gases. This work aims to clarify the combined effect of fungal agents and biochar on odor emission and provide a theoretical basis for developing an environmentally friendly in-situ efficient biological deodorization (IEBD) technology.

Emergence of superconducting dome in ZrNx films via variation of nitrogen concentration

Emergence of superconducting dome in ZrNx films via variation of nitrogen concentration

The noble gas and nitrogen relationship between Ryugu and carbonaceous chondrites

Carbonaceous chondrites are considered to have originated from C-type asteroids and represent some of the most primitive material in our solar system. Furthermore, since carbonaceous chondrites can contain significant quantities of volatile elements, they may have played a crucial role in supplying volatiles and organic material to Earth and other inner solar system bodies. However, a major challenge of unravelling the volatile composition of chondritic meteorites is distinguishing between which features were inherited from the parent body, and what may be a secondary feature attributable to terrestrial weathering. In December 2020, the Hayabusa2 mission of the Japan Aerospace Exploration Agency (JAXA) successfully returned surface material from the C-type asteroid (162173) Ryugu to Earth. This material has now been classified as closely resembling CI-type chondrites, which are the most chemically pristine meteorites. The analysis of material from the surface of Ryugu therefore provides a unique opportunity to analyse the volatile composition of material that originated from a CI-type asteroid without the complications arising from terrestrial contamination. Given their highly volatile nature, the noble gas and nitrogen inventories of chondrites are highly sensitive to different alteration processes on the asteroid parent body, and to terrestrial contamination. Here, we investigate the nitrogen and noble gas signature of two pelletized grains collected from the first and second touchdown sites (Okazaki et al., 2022a), to provide an insight into the formation and alteration history of Ryugu. The concentration of trapped noble gas in the Ryugu samples is greater than the average composition of previously measured CI chondrites and are primarily derived from phase Q, although a significant contribution of presolar nanodiamond Xe-HL is noted. The large noble gas concentrations coupled with a significant contribution of presolar nanodiamonds suggests that the Ryugu samples may represent some of the most primitive unprocessed material from the early solar system. In contrast to the noble gases, the abundance of nitrogen and δ15N composition of the two Ryugu pellets are lower than the average CI chondrite value. We attribute the lower nitrogen abundances and δ15N measured in this study to the preferential loss of a 15N-rich phase from our samples during aqueous alteration on the parent planetesimal. The analyses of other grains returned from Ryugu have shown large variations in nitrogen concentrations and δ15N indicating that alteration fluids heterogeneously interacted with material now present on the surface of Ryugu. Finally, the ratio of trapped noble gases to nitrogen is higher than CI chondrites, and is closer to refractory phase Q and nanodiamonds. This indicates that Ryugu experienced aqueous alteration that led to the significant and variable loss of nitrogen, likely from soluble organic matter, without modification of the noble gas budget, which is primarily hosted in insoluble organic matter and presolar diamonds and is therefore more resistant to aqueous alteration.

Spatiotemporal patterns of different forms of nitrogen in a coastal mangrove wetland invaded by Spartina alterniflora

The invasion by smooth cordgrass (Spartina alterniflora) has a serious impact on ecosystem function and the ecological environment in the coastal region of subtropical China. However, little is known about the fluctuation of different forms of nitrogen in mangrove wetlands invaded by cordgrass. In this study, we compared the spatial and temporal distribution of different forms of nitrogen with or without invasion by S. alterniflora in a coastal wetland in the Jiulong River estuary, Fujian province, China. The results revealed that the variation of nitrogen concentration in the wetland was closely related to the main intertidal vegetation type, season and sampling location. Organic nitrogen accounted for the majority of the deposited nitrogen and exhibited the highest values in the mangrove zone. The content of ammonium nitrogen and nitrate nitrogen was higher in cordgrass zone and lower in the mangrove, reaching a maximum in summer. Total nitrogen concentration was significantly influenced by the tidal water level which was highest in high tide zone and lowest at low tide. Invasion of S. alterniflora significantly altered nitrogen stocks in the sediment, including the contents of total nitrogen, total organic nitrogen, ammonium nitrogen and nitrate nitrogen.

Near-infrared leaf reflectance modeling of Annona emarginata seedlings for early detection of variations in nitrogen concentration

Near-infrared leaf reflectance modeling of Annona emarginata seedlings for early detection of variations in nitrogen concentration

Assessment and current dynamics of nutrients with reference to nitrogen attributes in subalpine forests of Western Himalaya, India.

Nitrogen is an essential macronutrient necessary for a variety of physiological processes in plants, available in numerous fractions, each of which has direct relationship with the area's environmental circumstances since it causes the formation of these fractions. Seasonal and altitudinal variations in nitrogen concentration were found to have a significant impact. The soil of the western Himalaya is rich in a variety of nutrients, notably nitrogen, which was a current source of worry. The study was conducted in north western Himalaya, and different fractions of nitrogen, viz., available nitrogen, total nitrogen, ammonical nitrogen, and nitrate nitrogen, were estimated with reference to different parameters. Annual retention potential was evaluated among various fractions, which yielded positive results, with Site 1 demonstrating the highest retention potential across all seasons. At various depths and seasons of the year, ammonical and nitrate nitrogen levels fluctuated. The findings revealed that the soil is rich in nitrogen fractions with variation directly related to changes in carbon dioxide concentration. Site 1 had the highest values of all the fractions and Site 4 the lowest, whereas the C/N ratio varied between sites. The study determined that nitrogen fractions were present in sufficient quantities and play an important role in the maintenance and growth of natural forests as well as in the reduction of carbon dioxide levels in the atmosphere.

Moisture movement, soil salt migration, and nitrogen transformation under different irrigation conditions: Field experimental research

Irrigation and fertilizer application can lead to significant changes in groundwater quality. In this study, a field irrigation experiment was carried out from April 9 to 23, 2021 under irrigation and fertigation conditions to understand the mechanisms of moisture movement, soil salt migration, and nitrogen transformation in the soil profile. Continuous in-situ monitoring and sampling of soil and irrigation water, as well as stable isotopes, chemical parameters, and soluble salt analyses, were performed in this research. The results showed that the time cost by the irrigation water in the vadose zone was about 5 h. The infiltrated irrigation water was accompanied by high concentrations of soluble salts, leached from the soil layers of 20–80 cm and 100–150 cm, which is associated with the leaching of Na+, Cl−, SO42−, and Ca2+ and the dissolution of minerals such as gypsum and halite. Furthermore, the variations in nitrogen concentrations (NH4+ and NO3−) in the soil profile suggested that fertilizer application was the main source of NO3− in the soil and groundwater, while irrigation was the biggest driving force for nitrogen transport and transformation in soil. The application of urea fertilizer can increase the content of ammonium nitrogen at the soil layer of 0–80 cm. This nitrogen form can be subsequently transformed to nitrate nitrogen during the water transport to the groundwater. The current study provides a strong scientific basis for the protection and management of groundwater and soil quality in agricultural areas.

Litter decomposition and properties of soil under Dalbergia sissoo, Acacia mangium and Eucalyptus tereticornis

The quantity of litter fall on the forest floor is quite high and they have a significant contribution to the dynamics of forest ecosystem. The present investigation was undertaken for litter quantification and its decomposition as per litterfall type, canopy also characteristics of soil in sole and mixed stands of Acacia mangium, Eucalyptus tereticornis and Dalbergia sissoo in agroforestry system. Quantification of litterfall and nutrient analysis was carried out for three trees i.e., Acacia mangium, Eucalyptus tereticornis and Dalbergia sissoo in agroforestry system. In the research area, sissoo stand has higher litterfall than mangium and Eucalyptus, being maximum litterfall occur in the month of January. The mean values for litterfall were 4000, 2200 and 1800 kg ha-1 year-1 for sissoo, mangium and eukalyptus stands, respectively. Annual decay constant was minimum for eucalyptus (k=0.161) whereas in sissoo it was (k=0.276), indicating the variability in nitrogen content among the types of litter (Sissoo, 2.25% and for Eucalyptus its 1.72%,). In conclusion it is stated that N rich litter may speed up for decomposition process.

Titanium nitride, TiXN(1−X), coatings deposited by HiPIMS for corrosion resistance and wear protection properties

The effect of nitrogen content on the structural, mechanical and corrosion properties of titanium nitride (TixN1−x) coatings deposited by high power impulse magnetron sputtering (HiPIMS) is investigated. The XRD results showed a (111) oriented crystalline structure at low nitrogen flow rate Qv(N2), and a mixed (111) and (200) at high Qv(N2). The average grain size was derived from XRD results and was found to increase with increasing N2 flow. The hardness results showed a maximum with variation of nitrogen content. All coatings exhibited excellent protection efficiency in acidic media compared to the uncoated steel samples, with protection efficiency reaching up to 98.9%. For reference, direct current magnetron sputtered (dcMS) coatings were deposited and investigated, confirming the superior performance of the HiPIMS coatings.

Variations of N concentrations and microbial community in the start-up of anammox using anaerobic heterotrophic sludge: Influence of a long reaction-phase time and comparison of the efficiencies of attached-versus suspended-growth cultures

Anaerobic sludge was capable of producing anaerobic ammonium oxidation (anammox) cultures. However, the low activity of anammox bacteria in the seed sludge often led to a long time for stable anammox to initiate. The objective of this study was to investigate the influence of an extended reaction-phase time in the sequencing batch reactor (SBR) on the rapid startup of anaerobic ammonium oxidation (anammox) using anaerobic heterotrophic bacteria as the seed sludge. After the startup, suspended and attached bacteria in anammox were separately analyzed for comparison. The variations of nitrogen concentrations and shifts of the microbial community structures were studied. The results showed that anammox occurred after a long reaction-phase time in the SBR with the efficient removals of NH4+ (96.4%) and NO2− (99.8%). The effective NO2− treatment before anammox startup was attributable to inevitable denitrification or dissimilatory nitrate reduction (e.g., Denitratisoma). The occurrence of anammox was supported by the anammox stoichiometry, bacteria diversity variation, and principal component analysis. The overall nitrogen removal rate (NRR) and nitrogen removal efficiency (NRE) was 0.07 kg/m3-d and 92.8%, respectively. The relative molar quantities of NH4+ and NO2− removed as well as N2 and NO3− formed were 1(1):1.29(1.32):1.45(1.02):0.15(0.26), as the numbers in the parentheses represent the theoretical values. Denitratisoma and Desulfatiglans dominated in the seed sludge, whereas Candidatus_Jettenia abundances were significantly higher in anammox attached- (26.0%) and suspended-growth cultures (14.5%). Fifty-three genera were simultaneously identified in all samples, suggesting their importance in the startup of anammox from anaerobic sludge. Candidatus_Jettenia was observed to be more associated with the growth of anammox biofilm (the abundances were 26.0% and 14.5% in attached- and suspended-growth cultures, respectively) and supported the fine nitrogen removal performance in the attached-growth cultures.

Analysis of surface diffusion of carbon- and nitrogen-containing molecules during homoepitaxial growth of 4H-SiC (0001) under silicon-rich conditions

Reported experimental results on homoepitaxial 4H-SiC grown by chemical vapor deposition on 1°- and 4°-off (0001) surfaces under silicon-rich conditions in a SiH4−C3H8−N2−H2 system are quantitatively analyzed according to surface diffusion theory dealing with step dynamics. The surface-diffusion lengths of carbon- and nitrogen-containing molecules are, respectively, estimated to be λ C = 25 nm and λ N ≥ λ C at 1773 K. This magnitude relationship agrees with the reported assumption made for the variation in nitrogen concentration on (000) facets of 4H-SiC grown by physical vapor transport.

Raman and Photoluminescence Study of Al,N‐Codoped ZnO Films Deposited at Oxygen‐Rich Conditions by Magnetron Sputtering

Optical properties of as‐grown high nitrogen‐doped ZnO:Al,N films (with a variation of nitrogen concentration from 2.3 to 4.3 atomic %) are studied by Raman, photoluminescence, and Fourier‐transform infrared spectroscopy (FTIR). The intensity of mode A1LO, peaked at 580 cm−1, increases with increasing nitrogen concentration. The silent mode B1low at 275 cm−1 is clearly observed testifying increased disorder‐activated scattering in ZnO. Photoluminescence spectra reveal near‐band edge emission as well as several defect‐related bands, the intensity of which increases with nitrogen content. The blue band (2.61 eV) can be related to the transition from shallow donor level to deep nitrogen acceptor level. Also, incorporation of nitrogen in ZnO lattice causes appearance of both Zni and Oi defects responsible for violet (3.08 eV) and yellow (2.16 eV) emission band, respectively. At the same time near‐band edge emission of ZnO:Al,N films is not suppressed by simultaneously introduced Al and N impurities. Al compensates distortions in ZnO crystal lattice caused by nitrogen doping and, thus, stabilizes near‐band edge emission.

Importance of the Submerged Zone during Dry Periods to Nitrogen Removal in a Bioretention System

Adding a submerged zone (SZ) is deemed to promote denitrification during dry periods and thus improve NO3− removal efficiency of a bioretention system. However, few studies had investigated the variation of nitrogen concentration in the SZ during dry periods and evaluated the effect of the variation on nitrogen removal of the bioretention system. Based on the experiment in a mesocosm bioretetion system with SZ, this study investigated the variation of nitrogen concentration of the system under 17 consecutive cycles of wet and dry alternation with varied rainfall amount, influent nitrogen concentration and antecedent dry periods (ADP). The results indicated that (1) during the dry periods, NH4+ concentrations in SZ showed an exponential decline trend, decreasing by 50% in 12.9 ± 7.3 h; while NO3− concentrations showed an inverse S-shape declining trend, decreasing by 50% in 18.8 ± 6.4 h; (2) during the wet periods, NO3− concentration in the effluent showed an S-shape upward trend; and at the early stage of the wet periods, the concentration was relatively low and significantly correlated with ADP, while the corresponding volume of the effluent was significantly correlated with the SZ depth; (3) in the whole experiment, the contribution of nitrogen decrease in SZ during dry periods to NH4+ and NO3− removal accounted for 12% and 92%, respectively; and the decrease of NO3− in SZ during the dry period was correlated with the influent concentration in the wet period and the length of the dry period.

Spectroscopic evidence of the origin of brown and pink diamonds family from Internatsionalnaya kimberlite pipe (Siberian craton)

New spectroscopic data were obtained to distinguish the specific features of brown and pink diamonds from Internatsionalnaya kimberlite pipe (Siberian craton). It is shown that pink and brown samples differ markedly in the content and degree of aggregation of nitrogen defects. Pink diamonds generally have higher nitrogen content and a lower aggregation state compared to brown samples, which often show significant variations in nitrogen content and aggregation state between different growth zones. The 491 and 576 nm luminescent centres, which are signs of deformed brown diamonds, are absent or of low intensity in pink diamonds implying that high nitrogen content predominantly in A form in the pink diamonds had stiffened the diamonds against natural plastic deformation. The GR1 centre, formed by a neutrally charged vacancy, was observed only in pink diamonds, which may be due to their formation and storage in the mantle at lower-temperature conditions. Mineral inclusions indicate peridotitic and eclogitic paragenesis for studied brown and pink diamonds, respectively. It is suggested that brown diamonds have been formed in a primitive mantle at higher temperatures and/or stored there much longer.

Temporal variation of stable isotopic values for dissolved nitrogen compounds in paddy water environment

Vietnam is the second-largest rice exporter worldwide and the amount of applied fertilizer is increasing rapidly in recent years. Overuse of chemical fertilizers in the paddy fields strongly contributes to the pollution of water bodies. This study aimed to understand the temporal variation of nitrogen concentrations and stable isotope values as environmental tracers based on the observed data in a selected paddy field in Vietnam, which provides basic and useful clues for tracing sources and identifying processes of nitrogen. The results from the field survey showed that , in accordance withthe changes in concentrations, δ15N values of ammonium and nitrate in ponded water drastically varied from -3.6‰ to 17.2‰ and from -18.2‰ to 8.5‰, respectively. The present study implied that not only chemical fertilizers but also irrigation water was the major source of nitrogen into the paddy. In addition, microbiological nitrification and denitrification were presumed based on the temporal isotopic variations.

Biochemical response of indigenous microalgal consortia to variations in nitrogen concentration of treated effluent

Cultivation conditions influence microalgal cellular components, such as lipid accumulation under nutrient depletion, high light irradiation and salinity stress. In this study, indigenous microalgal consortia were cultivated in batch mode using an actual treated effluent. The temporal response of cellular components to the variations in nitrogen concentration and influence of light irradiation on the response were investigated. Prolonged exposure of indigenous microalgal consortia to nitrogen exhaustion had minor effects on total lipid accumulation and enhancement of energy content. Nitrogen replenishment was followed by immediate crude protein accumulation for growth recovery. Total lipid reduction was observed under light and dark conditions after nitrogen replenishment. A one-day lag after nitrogen replenishment in the total lipid reduction was revealed under nitrogen depletion; meanwhile, under nitrogen exhaustion, lipids were utilised as the primary carbon and/or energy source after replenishment, as represented by the decrease from 10.8% to 9.04% within 6 h after the replenishment.

Investigation of the Nitrogen Content of Wheat According to Changing Meteorological Factors by Hermes Model

Investigation of the Nitrogen Content of Wheat According to Changing Meteorological Factors by Hermes Model Nilcan Altınbaş1*, Sami Kaya1, Elif İnan1, Barış Çaldağ1, Levent Şaylan11 Istanbul Technical University, Faculty of Aeronautics and Astronautics, Department of Meteorological Engineering, Istanbul, TURKEY[1]akatas@itu.edu.tr [1] Corresponding author: akatas@itu.edu.tr [*] ABSTRACT Ongoing increases in global population and expanding settlement areas brought by this situation have an important results like decreasing farmlands. Hence, it has great importance to increase the yield rates obtained from the unit area. As well known, crop yield is mainly affected by nitrogen content of soil and plant. Thus, in this study, it was aimed to investigate the nitrogen content in a wheat cultivated field by the help of a HERMES crop model by using some meteorological parameters collected from an experimental site in Kırklareli City of the Thrace Region located in northwestern part of Turkey. In this frame, possible effects of variations in meteorological parameters were simulated using the model. Variations in nitrogen content were determined under consideration of the winter wheat crop grown. Results were evaluated by means of the analysis of both plant and soil nitrogen contents. Key words: Mineralization, Climate Change, Yield, Winter Wheat [*] Corresponding author: akatas@itu.edu.tr

Effect of Saturated Zone on Nitrogen Removal Processes in Stormwater Bioretention Systems

The introduction of a saturated zone (SZ) has been recommended to address the issue of nitrogen removal fluctuation in the bioretention system, which is one of the most versatile low-impact development facilities for urban stormwater management. Nine experimental columns were used to characterize the nitrogen concentration variations over the outflow during wetting periods and in SZ during the antecedent drying periods (ADPs), as well as compare removal efficiencies of various nitrogen species in systems with different SZ depths under alternate drying and wetting conditions. Results indicated that NO3−-N concentrations in the outflow showed quasi-logistic curve-shaped variations over time: being low (&lt;0.5 mg/L) in the early process, sharply increasing thereafter, and finally flattening around 3.0 mg/L with NO3− leaching; NH4+-N and organic nitrogen (ON) concentrations were consistently low around 0.5 mg/L and 1.8 mg/L, respectively during the wetting periods. NH4+ removal efficiency in bioretention systems was consistently high around 80%, not varying with the increasing SZ depth; ON removal efficiency had a slight rise from 57% to 84% and NO3− removal efficiency was significantly enhanced from −23% to 62% with the SZ depth increasing from 0 to 600 mm. Deeper SZ could store more runoff and promote more denitrification of NO3− and mineralization of ON during the ADPs, providing more “old” water with low NO3− and ON concentrations for water exchange with “new” inflow of higher NO3− and ON concentrations during the wetting periods. The total nitrogen (TN) removal, a combined result of the instantaneous removal through adsorption and retention in the upper soil layer during the wetting periods and the gradual removal via denitrification and mineralization in SZ during the ADPs, was also improved by increasing the SZ depth; TN removal efficiency was elevated from 35% to 73% when the SZ depth increased from zero to 600 mm.