Differences In Total Nitrogen Research Articles

Influence of Typical Regional Land Use/Landscape Pattern on Water TN of the Upper Yellow River

This study aimed to explore the relationship between land use landscape pattern and water quality in the upstream of the Gansu water conservation, water and soil erosion, and ecological fragile areas. Based on the land use data and water quality monitoring section in 2020 in the 200 m, 500 m, 1 km, 2 km, 50 km, and 10 km riparian buffer area, the single-factor index evaluation method, random forest regression model, and BP neural network were used to quantify the response relationship between land use and landscape pattern of the upper Yellow River in Gansu province and water quality index and to carry out the basin water quality prediction based on land use landscape index data. The results showed that： ① through the single-factor index method, the major indicators of the total nitrogen （TN） in July and September, dissolved oxygen （DO）, permanganate index, ammonia nitrogen （NH4+ -N）, total phosphorus （TP）, and other surface indexes met the surface water environment class Ⅲ water quality standard. ② The random forest regression model was used to analyze the influence of land use and landscape index on TN, and the difference in TN in different typical areas was obtained. The land use types with the highest influence on the TN index in water conservation areas, soil and soil erosion areas, and ecological fragile areas were cultivated land, grassland, and construction land, respectively. ③ The BP neural network was used to predict the water quality index based on different typical areas of land use landscape index. The result of water conservation areas was good, the error rate between the predicted value and the actual value was below 10%, and the prediction accuracy was high. The study showed that water quality prediction based on land use and landscape index/water quality quantitative relationship model had a good water quality prediction effect.

Stocks and Sources of Soil Carbon and Nitrogen in Non-Native Kandelia obovata Afforestation and Spartina alterniflora Invasion: A Case Study on Northern Margin Mangroves in the Subtropical Coastal Wetlands of China

For decades in China, carbon neutrality policies have spurred the establishment of northern margin mangroves as artificial blue carbon ecosystems. However, there has been limited research on the impact of plantation and invasion on the stocks and sources of soil carbon and nitrogen in rehabilitated coastal wetlands. Non-native Kandelia obovata afforestation began on Ximen Island, Zhejiang, China, where Spartina alterniflora invasion had also occurred decades ago. Soil cores were collected from both mangrove and salt marsh habitats with depths from 0 to 50 cm and were analyzed for total carbon (TC), soil organic carbon (SOC), total nitrogen (TN), and the isotope of carbon and nitrogen in sediments. The results indicated that there were no significant differences in the TC, SOC, and C/N ratio between the K. obovata and the S. alterniflora, but there were significant differences in TN, isotope δ13C, and δ15N. The SOC content of both ecosystems in the 0–20 cm layer was significantly higher than that in the 30–50 cm layer. Our study has shown that the main sources of carbon and nitrogen for mangroves and salt marshes are different, especially under the impact of external factors, such as tidal waves and aquaculture. These findings provide insight into the ecological functioning of subtropical coastal wetlands and an understanding of the biogeochemical cycles of northern margin mangrove ecosystems.

Effects of straw-returning combined with application of microbial inoculants on soil aggregates and related nutrients

We analyzed the particle size distribution of soil aggregates in 0-20 and 20-40 cm soil layers of rice-wheat rotation field based on a field plot test with two treatments, conventional straw returning (CK) and straw returning with the addition of straw decomposition promoting microbial inoculants (IT). We evaluated the water stability indices of soil aggregates (the number of soil water stable large aggregates R0.25, the average weight diameter MWD, and the geometric average diameter GMD), and measured the contents of soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) in the soil aggregates of ＜0.053, 0.053-0.25, 0.25-1, ＞1 mm. The results showed that: 1) The number of aggregates ＜0.053, 0.053-0.25, ＞0.25 mm in the 0-20 and 20-40 cm soil layers under IT decreased by 10.0% and 6.8%, increased by 3.0% and 5.7%, and 17.9% and 26.1% compared with CK, respectively. IT effectively increased R0.25, MWD, and GMD by 26.4%, 20.0%, 18.2% and 18.2%, 10.5%, 10.0% in 0-20 and 20-40 cm soil, respectively. 2) Compared to CK, the TP content of 0.25-1 mm aggregates in 0-20 and 20-40 cm soil under IT was significantly increased by 40.3% and 37.5%, respectively, without difference in TN and SOC contents. There was no significant difference in nutrient contents of the other aggregates between the treatments. The contents of SOC and TN in large aggregates (>0.25 mm) were higher than those in silty aggregates (<0.053 mm). Compared to CK, the cumulative contribution rates of SOC, TN and TP of <0.053 mm aggregates under IT were decreased in two soil layers. There was no significant difference in the nutrient cumulative contribution rates of 0.053-0.25 mm aggregates between treatments. The cumulative contribution rates of SOC, TN, and TP of large aggregates (>0.25 mm) under IT were 32.1%, 19.6%, 52.8% and 22.8%, 11.8%, 42.9% higher than those under CK in 0-20 and 20-40 cm soils, respectively. 3) The number of <0.053 mm aggregates was significantly negatively correlated with SOC and TP contents, while that of 0.053-0.25 mm aggregates was negatively correlated with nutrient content. The number of large aggregates (>0.25 mm) were significantly positively correlated with SOC, TN, and TP contents. In conclusion, straw returning with microbial-inoculant addition could promote the formation of soil macroaggregates (>0.25 mm), and improve the water stability of soil aggregates, increasing nutrient contents in soil macroaggregates, with the nutrients transferring from silty aggregates to macroaggregates.

Nutrient dynamics and microbial community response in macrophyte-dominated lakes: Implications for improved restoration strategies

Although lakes dominated by macrophytes are conducive to ecological balance, this balance is easily disrupted by excessive nutrients flowing into the lake. However, knowledge of whether excessive nutrients lead to different microbial environmental vulnerabilities in the lake sediment between macrophyte-dominated areas and macrophyte-free areas is a prerequisite for the implementation of targeted protection measures. In this study, we investigated bacterial communities in sediments using high-throughput sequencing of 16S rRNA genes. Our results showed that the sources of total nitrogen (TN) and organic matter (OM) were related to the macrophytes. The structure, drivers, and interspecific associations of bacterial community, which were more susceptible to increased changes in TN and OM, differed significantly between macrophyte-dominated areas and macrophyte-free areas. More precisely, the lake edge, where was occupied by macrophytes, had a higher proportion of deterministic phylogenetic turnover (88.89%) than other sites, as well as a wider ecological niche and a tighter network structure. Further, as the difference in TN increased, the main assembly processes in surface sediments changed from stochastic to deterministic. However, the majority of phyla from the lake edge showed a greater correlation with excessive nutrients, and the selection of the community by excessive nutrients was more obvious at the edge of the lake. In addition, our results demonstrated that the stability of the bacterial community in macrophyte-free areas is greater than in macrophyte-dominated areas, while an excessively high deterministic process ratio and nutrient (TN and OM) concentration significantly reduced bacterial community stability at macrophyte-dominated areas. Taken together, these results provide a better understanding of the effects of excessive nutrients derived from macrophytes on bacterial community patterns, and highlight the importance of avoiding the accumulation of TN and OM in macrophyte-dominated areas to enhance the sustainability of the ecosystem after restoration of lakes with macrophytes.

Nitrogen Content in Craft Malts: Effects on Total Ester Concentration in Beer

Malt is an essential ingredient in beer; not only because it provides yeast with essential nutrients such as amino acids and fermentable sugars, it also adds to the beer’s color, body and flavor. The objective of this project was to look at the initial concentration of total nitrogen (TN) found within base malts of different varietal and cultivar origins and its impact on the esters produced in beers made using these malts. The experimental beer was brewed with a target OG of 10° Plato wort using five different base malts; four of which were produced by independent craft maltsters (Texas, Oregon, Indiana, and Canada) and a macro-industrial produced malt served as the control. TN and free amino nitrogen (FAN) were analyzed and compared with volatile and semi-volatile flavor analysis in order to identify correlations between nitrogen concentration and ester development within the final beer. One-way ANOVA coupled with a Tukey HSD paired comparison test was run to determine statistical differences in TN and FAN, while Kruskal-Wallis one-way analysis of variance test was utilized to determine statistical differences between total esters production. TN wort values ranged from 627 to 909 mg/L, while FAN wort values ranged from 191 to 467 mg FAN/L. There were statistical differences seen between all of the beers in total ester production. The beers produced with malts of higher TN resulted in greater ester production. From this, one can conclude that there is a correlation between a malt’s TN and esters produced in the final beer product.

Soil fertility status of agricultural land in mid-hill of Gorkha District, Nepal

Soil fertility management in agricultural land is challenging in hilly areas of Nepal. The study assesses the soil fertility status of Bari (upland) and Khet (lowland) agriculture land in Mid-hill of Gorkha district. Altogether 30 samples were collected from soil surface (0 to 20 cm) by using hand shovel in January, 2017. The soil fertility parameters like pH, organic matter (OM), total nitrogen (TN), available phosphorus (P) and available potassium (K) were analyzed using standard methods in the laboratory of Central Department of Environmental Science, Tribhuvan University. Results revealed that an average pH in upland (6.62) was higher than the lowland (5.94). Similarly, OM (3.95%) and K (36.49 kgha-1) were relatively high in upland. In addition, pH, OM and available K were significantly varied at p&lt;0.05 in upland and lowland soils, however, there is no significant difference in TN and available P. In addition, soil nutrient index showed that status of available K in both types of land is low, while OM and TN are medium soil quality in upland and lowland soil. The use of organic fertilizer and improved farming system can maintain and sustain soil fertility for crop growth and yield. Understanding distribution of soil nutrients in the study area might be useful for planners to make effective soil fertilizer management strategies.

Biological Nitrogen Fixation by Local and Improved Genotypes of Cowpea in Burkina Faso (West Africa): Total Nitrogen Accumulated can be used for Quick Estimation

Biological nitrogen fixation (BNF) by legumes is an indicator of their potential contribution to recycling nitrogen in cropping systems. Many techniques exist for the quantitative measurement of legume BNF. The isotopic dilution (ID) methods are the most accurate but are too expensive, time-consuming and require technical expertise. There is a gap between the simple but less accurate Total Nitrogen Difference (TND) method and the Isotopic Dilution (ID) methods. By measuring the BNF of 11 cowpea (Vigna unguiculata) genotypes, this study aimed to develop a simple model as an improved tool for the quick estimation of BNF. Total N accumulated by traditional genotypes from Burkina Faso varied from 23 to 41 kg ha−1. Approximately 40 to 65% of this was nitrogen derived from the atmosphere (Ndfa) when the TND method was used (Ndfa-TND), while the ID method indicated that 29 to 37% of N accumulated was derived from the atmosphere (Ndfa-ID). The TND method overestimated the BNF of high N-yielding genotypes but underestimated the BNF of low N-yielding genotypes (N-accumulated below 31 kg N ha−1). The relationship between N-accumulated and Ndfa-ID was described by a polynomial regression: Yi = 0.0127 Xi2 - 0.5354 Xi + 17.44, where Yi and Xi represent Ndfa-ID and N-accumulated, respectively (P&lt;0.05, R2 =0.92). The model was validated and could be used for quick estimation of BNF directly from the N accumulated.

Effects of vegetation, terrain and soil layer depth on eight soil chemical properties and soil fertility based on hybrid methods at urban forest scale in a typical loess hilly region of China.

Although the spatial mapping and fertility assessment of soil chemical properties (SCPs) are well studied in the Loess Plateau region of China at farmland scale, little is known about spatial mapping the SCPs and their fertility and their influence factors at urban forest scale. The objectives of this study were to (1) compare the performance of two spatial interpolation methods, Ordinary kriging (OK) and regression kriging (RK), and (2) explain the relationships of the vegetation, terrain, and soil layer depth between the eight SCPs and their fertility, and (3) find the limiting factors of soil comprehensive fertility in this study area? The Yan’an urban forest was taken as study case, used hybrid spatial interpolation methods based on OK and RK to mapping eight SCPs and the soil fertility in each soil layer (0–20 cm, 20–40 cm, and 40–60 cm) for 285 soil samples. The results indicated that RK outperformed OK for total nitrogen (TN), available potassium (AK), organic matter (OM) in 0–60 cm profile and available phosphorus (AP) in the 0–20 cm and 40–60 cm soil layers because RK considered the impact of terrain. The terrain factors, comprising the relative terrain position, slope, aspect, and relative elevation significantly affected the SCPs and spatial heterogeneity of fertility, where the vegetation cover types determined the average SCPs to some extent. On average, the six SCPs (except total potassium and AP) and the fertility decreased as the soil layer depth increased. Ten vegetation cover types comprising broadleaved mixed natural forest (BM), cultivated land (CL), economic forest (EF), grassland (GL), Platycladus orientalis natural forest (PON), Platycladus orientalis plantation (POP), Pinus tabuliformis plantation (PT), Quercus wutaishanica natural forest (QW), Robinia pseudoacacia plantation (RP), and Shrubwood (SW) were associated with significant differences in TN, OM, AN, AP, and AK, across the three soil layers. QW, PON, and BM also had higher content of TN, OM, AN, and AK contents than the other vegetation cover types. There were small differences in TK, AK, and pH among the 10 vegetation cover types. We concluded that AN, TN, and OM are the limiting factors of soil comprehensive fertility in this region. These results improve understanding of the spatial mapping, influence and limiting factors of SCPs and their fertility at urban forest scales.

Pollution and ecological risk assessment of nutrients associated with deposited sediments collected from roof and road surfaces.

Surface-deposited sediment in urban areas is an essential environmental medium for assessing nutrient contamination. The total nitrogen (TN) and total phosphorus (TP) pollution associated with surface-deposited sediments can be transported into urban water bodies by runoff and can cause eutrophication of those water bodies. By analyzing the samples collected on roof surfaces and road surfaces, this study provides a comparison of the differences in TN and TP pollution loading in sediments on these two different impervious surface materials. Also, an assessment of the ecological risk of nutrients in surface-deposited sediments with respect to grain size fraction was performed. The results indicate that the TN and TP pollution loading in both road-deposited sediments and roof-deposited sediments indicated an asymmetric "W" trend along with grain size fraction, and both road-deposited sediments and roof-deposited sediments had the highest TN and TP pollution contribution when the particle size is between 250 and 500μm. TN in roof-deposited sediments has high ecological risk when the particle size is less than 250μm. These findings help to provide guidance for the management of surface-deposited sediment pollution.

Factor controlling soil organic carbon and total nitrogen dynamics under long-term conventional cultivation in seasonally frozen soils

Limited information is available for understanding factors controlled dynamics of soil organic carbon (SOC) and total nitrogen (TN) affected by long-term conventional cultivation in seasonally frozen soils. A 19-year observation in this study was conducted in north-eastern China to evaluate effects and relative importance of potential factors. SOC variation extent was greater relative to global average as per unit of annual mean air temperature and precipitation changed. Increased carbon sequestration was observed in meadow lessive, while slight to moderate declines occurred in meadow-boggy soil and meadow soil. However, no differences in TN were found across soil types. At sites with low slope, carbon and nitrogen sequestration increased, largely due to water movement. Increased biomass with introducing 1-year oilseed rape/fallow in crop rotations could promote SOC and TN accumulation in the long run. Planting proportion of crops could also regulate carbon and nitrogen levels at a farm scale; the optimal ratio was observed in the range of 0.8–1.4. High crop yield was associated with lower carbon and nitrogen levels, and nutrient thresholds of yielding increment were observed as 25.7 g kg−1 for carbon and 2.6 g kg−1 for nitrogen. The length of frost-free period or cultivation period could not help sequestrating carbon and nitrogen. Chemical fertilizer with crop residues provoked SOC and TN increments compared with no chemical fertilizer plus little organic manure. Different factors exerted different tendentious influences, leading to subtle differences in SOC and TN variation rates. Accordingly, optimal cultivation strategies could be developed to reduce nutrient losses and mitigate greenhouse gas emissions.

Comparative Nitrogen fixation, native arbuscular mycorrhiza formation and biomass production potentials of some grain legume species grown in the iield in the Guinea Savanna Zone of Ghana

An on-station trial was conducted in the experimental field of Savanna Agricultural Research Institute at Nyankpala in the Northern Region of Ghana to assess the nitrogen fixation, native arbuscular mycorrhizal formation and biomass production potentials of cowpea (Vigna unguiculata), devil-bean (Crotalaria retusa), Mucuna pruriens var. utilis(black and white types) and Canavalia ensiformis with maize (Dorke SR) as the reference crop using the total nitrogen difference (TND) method. Plants were fertilized with 40 kg P/ha and 30 kg K/ha at 2 weeks after planting and grown for 55 days after which they were harvested. The harvested biomass (separated into roots, stems and leaves) of eachcrop was oven-dried at 70 oC for 48 h to a constant weight. Cowpea and devil-bean produced approximately 5 and 6 t/ha biomass whereas Mucuna and Canavalia yielded about 2 t/ha biomass each. Although cowpea had the least number of arbuscular mycorrhiza fungal (AMF) spores in its rhizosphere, its roots were the most heavily colonized (34%) and M. pruriens recording below 5% colonization. Apart from C. ensiformis, the test legumes derived over 50% of their total accumulated N from the atmosphere with cowpea being the most efficient (90% Ndfa). Both N and Paccumulations were significantly higher in cowpea than the other legumes due to increased N concentration and dry matter accumulation, respectively. In all the legumes, there was a direct positive correlation between the extent of mycorrhiza formation, biological N fixation and total N uptake. It could, therefore, be concluded that the extensivemycorrhiza formation in cowpea and its high N2-fixing potential resulted in a high shoot N and P uptake leading to a comparatively better growth enhancement. Cowpea could, therefore, be the grain legume for consideration in the selection of a suitable legume pre-crop to cereals for the amelioration of the low fertility of the degraded soils of the Guinea savanna zone of Ghana, and also as a source of food to fill the hunger gap that precedes the growing season in the Northern Region of Ghana.

Intra- and inter-annual variability in the different forms of diffuse nitrogen and phosphorus delivered to seven sub-tropical east Australian estuaries

Intra- and inter-annual variability in the different forms of diffuse nitrogen and phosphorus delivered to seven sub-tropical east Australian estuaries was examined using river concentration data collected in 1996 and historical flow records. Rainfall during the study period was above average due to high rainfall in January, May and November (southern catchments only) which resulted in early January and May, and late November (southern catchments only), floods. A total load of 12,321 t of nitrogen and 1594 t of phosphorus was exported from the seven catchments during 1996. Percentage forest cover was a good predictor of total phosphorus (TP) exports (kg/km 2/mm) and a weak predictor of total nitrogen (TN) exports (kg/km 2/mm), except for the Bellinger and Manning catchments where high exports from non-forested land uses masked the percentage forest cover/export relationship. Intra-annual variability was large due to the three floods transporting up to 76% of the annual TN load and 73% of the annual TP load from individual catchments. As such, 75% of the annual TN and TP loads in all seven catchments were transported in less than 20% of the time. This contrasts with typical temperate systems where it takes 50% or more of the time to deliver 75% of the annual load. Inter-annual variability was also larger than typical temperate systems with up to a 29 times difference in TN and TP loads between years over the period of historical flow records (approximately 50 years). The large intra- and inter-annual variability reflects Australia's highly variable hydrology. Nitrogen exports were dominated by organic forms with an average of about 80% of the TN load consisting of particulate nitrogen (PN) and dissolved organic nitrogen (DON) reflecting the high percentage forest cover in the catchment. Phosphorus loads were more evenly distributed between the three forms, dissolved inorganic phosphorus (DIP), particulate phosphorus (PP) and dissolved organic phosphorus (DOP).

Assessment of biological nitrogen fixation

The four commonly used methods for measuring biological nitrogen fixation (BNF) in plants are: the total nitrogen difference (TND) method, acetylene reduction assay (ARA) technique, xylem-solute (or ureide production) method and the use of15N labelled compounds.

Sugarcane Production Impact on Nitrogen and Phosphorus in Drainage Water from an Everglades Histosol

AbstractThe Everglades Agricultural Area (EAA) in southern Florida is a 280 000‐ha tract of land that has come under scrutiny by environmental, agricultural industry, and government water management groups that are concerned with the impact of nutrient‐enriched drainage water on the ecology of adjoining bodies of water and wetlands. Sugarcane (Saccharum sp.) is grown on 155 000 ha or 78% of the cultivated organic soils in the EAA. The objectives of this study were to determine the N and P concentrations and off‐field loads in drainage water from sugarcane and fallow fields. Sugarcane was planted in four of eight hydraulically independent and similar field plots. Four plots were maintained fallow. Drainage water volume, and total nitrogen (TN), total dissolved phosphorus (TDP), and total phosphorus (TP) concentrations were monitored during 12 drainage events during two crop seasons. For two drainage events, TN concentrations were higher in drainage water from fallow plots that in drainage water from sugarcane plots and it was speculated that crop uptake of mineralized soil N may have contributed to the reductions during these events. Analysis of the mean for the 12 drainage events indicated no overall differences in TN off‐field loads between sugarcane and fallow plots. Further, no significant differences were found in TDP or TP concentration in drainage water from sugarcane and fallow plots during any of the drainage events monitored. It was concluded that, due to the large quantity of soil N and P mineralized and due to crop N and P uptake, the impact of sugarcane production on drainage water N and P concentrations was minimal.

Estimation de la fixation d'azote atmospherique par le tracage isotopique naturel dans une plantation de Casuarina equisetifolia (forst)

A field experiment was established at Notto in Senegal, in a sandy dune soil, to evaluate the percentage of nitrogen derived from the atmosphere (Ndfa %) by a 3yr old Casuarina equisetifolia plantation using both the total nitrogen difference (TND) and the natural 15N abundance methods (NA). Ndfa % based on the total nitrogen difference method was 33 ± 10 when 20 inoculated and 20 uninoculated trees were sampled, 32 ± 8 when the sampling comprised 8 inoculated trees with 8 uninoculated C. equisetifolia as reference trees and 24 ± 8 with Eucalyptus camaldulensis as reference trees. Ndfa % based on the natural abundance method was 39 ± 12, the sampling comprising 8 uninoculated and 8 inoculated C. equisetifolia trees and 37 ± 12 when E. camaldulensis was used as reference tree instead of C. equisetifolia. A complementary experiment simulating field conditions was carried out in another sandy soil (Bel-Air) with the same tree species. It showed that Ndfa % was 37 ± 14 (TND method) or 39 ± 6 (NA method). Thus the TND and NA methods appear to provide similar estimations, a conclusion which can probably be extrapolated to soil types similar to the Senegalese sandy soil used in this work. To calculate the Ndfa % using the natural abundance method, it was necessary first to estimate the isotopic enrichment factor associated with dinitrogen fixation (ϵ fix) of C. equisetifolia. This was found to be −0.98 + 0.5%. (calculation based on two clones α and β). Based on the mean Ndfa % (38%), the amount of nitrogen fixed in the semi arid condition of Senegal was 15 kgN ha −1 year −1. This modest amount of nitrogen fixed was attributed to the low soil fertility and to the fact that the Notto station is far from the sea and consequently does not benefit from the high air humidity in the coastal zone.