scholarly journals Revisiting Biological Nitrogen Fixation Dynamics in Soybeans

2021 ◽  
Vol 12 ◽  
Author(s):  
Ignacio A. Ciampitti ◽  
André Froes de Borja Reis ◽  
S. Carolina Córdova ◽  
Michael J. Castellano ◽  
Sotirios V. Archontoulis ◽  
...  
Keyword(s):  
Maximum Rate ◽  
Seasonal Pattern ◽  
Single Point ◽  
Clay Content ◽  
Growth Stages ◽  
N Fixation ◽  
N Budget ◽  
Fixation Rate ◽  
N Removal ◽  
Biological Nitrogen

Biological nitrogen (N) fixation is the most relevant process in soybeans (Glycine max L.) to satisfy plant N demand and sustain seed protein formation. Past studies describing N fixation for field-grown soybeans mainly focused on a single point time measurement (mainly toward the end of the season) and on the partial N budget (fixed-N minus seed N removal), overlooking the seasonal pattern of this process. Therefore, this study synthesized field datasets involving multiple temporal measurements during the crop growing season to characterize N fixation dynamics using both fixed-N (kg ha−1) and N derived from the atmosphere [Ndfa (%)] to define: (i) time to the maximum rate of N fixation (β2), (ii) time to the maximum Ndfa (α2), and (iii) the cumulative fixed-N. The main outcomes of this study are that (1) the maximum rate of N fixation was around the beginning of pod formation (R3 stage), (2) time to the maximum Ndfa (%) was after full pod formation (R4), and (3) cumulative fixation was positively associated with the seasonal vapor-pressure deficit (VPD) and growth cycle length but negatively associated with soil clay content, and (4) time to the maximum N fixation rate (β2) was positively impacted by season length and negatively impacted by high temperatures during vegetative growth (but positively for VPD, during the same period). Overall, variation in the timing of the maximum rate of N fixation occurred within a much narrower range of growth stages (R3) than the timing of the maximum Ndfa (%), which varied broadly from flowering (R1) to seed filing (R5–R6) depending on the evaluated studies. From a phenotyping standpoint, N fixation determinations after the R4 growth stage would most likely permit capturing both maximum fixed-N rate and maximum Ndfa (%). Further investigations that more closely screen the interplay between N fixation with soil-plant-environment factors should be pursued.

scholarly journals Nitrogen cycling in Sandusky Bay, Lake Erie: oscillations between strong and weak export and implications for harmful algal blooms

2018 ◽  
Vol 15 (9) ◽  
pp. 2891-2907 ◽  
Author(s):  
Kateri R. Salk ◽  
George S. Bullerjahn ◽  
Robert Michael L. McKay ◽  
Justin D. Chaffin ◽  
Nathaniel E. Ostrom
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Lake Erie ◽  
N Uptake ◽  
N Fixation ◽  
N Budget ◽  
N2o Production ◽  
N Removal ◽  
Uptake Rates ◽  
N Loading

Abstract. Recent global water quality crises point to an urgent need for greater understanding of cyanobacterial harmful algal blooms (cHABs) and their drivers. Nearshore areas of Lake Erie such as Sandusky Bay may become seasonally limited by nitrogen (N) and are characterized by distinct cHAB compositions (i.e., Planktothrix over Microcystis). This study investigated phytoplankton N uptake pathways, determined drivers of N depletion, and characterized the N budget in Sandusky Bay. Nitrate (NO3-) and ammonium (NH4+) uptake, N fixation, and N removal processes were quantified by stable isotopic approaches. Dissimilatory N reduction was a relatively modest N sink, with denitrification, anammox, and N2O production accounting for 84, 14, and 2 % of sediment N removal, respectively. Phytoplankton assimilation was the dominant N uptake mechanism, and NO3- uptake rates were higher than NH4+ uptake rates. Riverine N loading was sometimes insufficient to meet assimilatory and dissimilatory demands, but N fixation alleviated this deficit. N fixation made up 23.7–85.4 % of total phytoplankton N acquisition and indirectly supports Planktothrix blooms. However, N fixation rates were surprisingly uncorrelated with NO3- or NH4+ concentrations. Owing to temporal separation in sources and sinks of N to Lake Erie, Sandusky Bay oscillates between a conduit and a filter of downstream N loading to Lake Erie, delivering extensively recycled forms of N during periods of low export. Drowned river mouths such as Sandusky Bay are mediators of downstream N loading, but climate-change-induced increases in precipitation and N loading will likely intensify N export from these systems.

scholarly journals The nitrogen pendulum in Sandusky Bay, Lake Erie: Oscillations between strong and weak export and implications for harmful algal blooms

2018 ◽  
Author(s):  
Kateri R. Salk ◽  
George S. Bullerjahn ◽  
Robert Michael L. McKay ◽  
Justin D. Chaffin ◽  
Nathaniel E. Ostrom
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Lake Erie ◽  
N Uptake ◽  
N Fixation ◽  
N Budget ◽  
N2o Production ◽  
N Removal ◽  
Uptake Rates ◽  
N Loading

Abstract. Recent global water quality crises point to an urgent need for greater understanding of cyanobacterial harmful algal blooms (cHABs) and their drivers. Nearshore areas of Lake Erie such as Sandusky Bay may become seasonally limited by nitrogen (N) and are characterized by distinct cHAB compositions (i.e., Planktothrix over Microcystis). This study investigated phytoplankton N uptake pathways, determined drivers of N depletion, and characterized the N budget in Sandusky Bay. Nitrate (NO3−) and ammonium (NH4+) uptake, N fixation, and N removal processes were quantified by stable isotopic approaches. Dissimilatory N uptake was a relatively modest N sink, with denitrification, anammox, and N2O production accounting for 84, 14, and 2 % of N removal, respectively. Phytoplankton assimilation was the dominant N uptake mechanism, and NO3− uptake rates were higher than NH4+ uptake rates. Riverine DIN loading was sometimes insufficient to meet assimilatory and dissimilatory demands, but N fixation alleviated this deficit. N fixation made up 23.7–85.4 % of total phytoplankton N acquisition and indirectly supports Planktothrix blooms. However, N fixation rates were surprisingly uncorrelated with NO3− or NH4+ concentrations. Owing to temporal separation in sources and sinks of N to Lake Erie, Sandusky Bay pendulums between acting as a strong and weak source of downstream N loading to Lake Erie. Estuarine systems such as Sandusky Bay are mediators of downstream N loading, but climate change-induced increases in precipitation and N loading will likely intensify the swings of the N pendulum in favor of N export.

scholarly journals The maximum rate of convergence for the approximation of the fractional Lévy area at a single point

2016 ◽  
Vol 33 ◽  
pp. 107-117
Author(s):  
Andreas Neuenkirch ◽  
Taras Shalaiko
Keyword(s):  
Rate Of Convergence ◽  
Maximum Rate ◽  
Single Point

scholarly journals Effect of soil interacting herbicides on soybean nodulation in Balcarce, Argentina

1999 ◽  
Vol 34 (7) ◽  
pp. 1167-1173 ◽  
Author(s):  
Norma Gonzalez ◽  
Juan Jose Eyherabide ◽  
Maria Ignacia Barcelonna ◽  
Alfredo Gaspari ◽  
Silvina Sanmartino
Keyword(s):  
Organic Matter ◽  
Dry Weight ◽  
Control Treatment ◽  
Growth Stages ◽  
N Fixation ◽  
Buenos Aires Province ◽  
N Accumulation ◽  
Nodule Number ◽  
Seed Growth ◽  
Chlorimuron Ethyl

Two trials were performed in Balcarce, Argentina (37° 45' LS; 58° 18' LW) during 1993-94, to assess the effect of eight herbicides applied individually or in tank mixtures, on nodule number, nodule dry weight, seed yield and N percent in seed in soybean Asgrow 3205, inoculated with Bradyrhizobium japonicum CB 1809. Individual herbicides and doses in kg ha-1 of a.i. were metribuzin (0.48), acetochlor (0.90), metolachlor (1), flumioxazin (0.075), trifluralin (0.96), imazaquin (0.20), imazethapyr (0.10) and chlorimuron ethyl (0.0125). The mixtures were metribuzin+acetochlor (0.48+0.9), flumioxazin+acetochlor (0.075+0.9), imazaquin+acetochlor (0.2+0.9), metribuzin+metolachlor (0.48+1.92), and flumioxazin+ metolachlor (0.075+1.92). A control treatment without herbicides was included. Both trials were laid out as randomized complete blocks with four replicates, on a loam illitic thermic petrocalcic Paleudoll, 5.7% organic matter (OM), 25% clay, 30.4 cmol kg-1 CEC. Nodules were sampled at V2 (second node), V6 (sixth node) and R5 (beginning seed) growth stages. Herbicides did not significantly affect the beginning of nodulation or nodule number and mass at R5, not either grain yield or N accumulation. This indicates lack of interference between soil interacting herbicides and N fixation in the high organic matter, loam soils of SE Buenos Aires province, even though a tendency in less number and dry weight of nodules was evident at the two latter growth stages.

scholarly journals Spatiotemporal patterns of N<sub>2</sub> fixation in coastal waters derived from rate measurements and remote sensing

2021 ◽  
Vol 18 (5) ◽  
pp. 1857-1871
Author(s):  
Mindaugas Zilius ◽  
Irma Vybernaite-Lubiene ◽  
Diana Vaiciute ◽  
Donata Overlingė ◽  
Evelina Grinienė ◽  
...  
Keyword(s):  
Remote Sensing ◽  
N2 Fixation ◽  
Phytoplankton Community ◽  
Coastal Lagoons ◽  
Curonian Lagoon ◽  
Strong Correlations ◽  
N Budget ◽  
Chl A ◽  
Heterocystous Cyanobacteria ◽  
N Removal

Abstract. Coastal lagoons are important sites for nitrogen (N) removal via sediment burial and denitrification. Blooms of heterocystous cyanobacteria may diminish N retention as dinitrogen (N2) fixation offsets atmospheric losses via denitrification. We measured N2 fixation in the Curonian Lagoon, Europe's largest coastal lagoon, to better understand the factors controlling N2 fixation in the context of seasonal changes in phytoplankton community composition and external N inputs. Temporal patterns in N2 fixation were primarily determined by the abundance of heterocystous cyanobacteria, mainly Aphanizomenon flos-aquae, which became abundant after the decline in riverine nitrate inputs associated with snowmelt. Heterocystous cyanobacteria dominated the summer phytoplankton community resulting in strong correlations between chlorophyll a (Chl a) and N2 fixation. We used regression models relating N2 fixation to Chl a, along with remote-sensing-based estimates of Chl a to derive lagoon-scale estimates of N2 fixation. N2 fixation by pelagic cyanobacteria was found to be a significant component of the lagoon's N budget based on comparisons to previously derived fluxes associated with riverine inputs, sediment–water exchange, and losses via denitrification. To our knowledge, this is the first study to derive ecosystem-scale estimates of N2 fixation by combining remote sensing of Chl a with empirical models relating N2 fixation rates to Chl a.

scholarly journals Biotechnological approaches to develop nitrogen-fixing cereals: A review

2021 ◽  
Vol 19 (4) ◽  
pp. e08R01-e08R01
Author(s):  
Asma Boujenna ◽  
Keyword(s):  
Cereal Crops ◽  
N Fixation ◽  
N Availability ◽  
Environmental Consequences ◽  
Industrialized Nations ◽  
Oxygen Sensitive ◽  
Legume Symbiosis ◽  
Living Organisms ◽  
Agricultural Yields ◽  
Biological Nitrogen

Agricultural yields are often limited by nitrogen (N) availability, especially in countries of the developing world, whereas in industrialized nations the application of chemical N fertilizers has reached unsustainable levels that have resulted in severe environmental consequences. Finding alternatives to inorganic fertilizers is critical for sustainable and secure food production. Although gaseous nitrogen (N2) is abundant in the atmosphere, it cannot be assimilated by most living organisms. Only a selected group of microorganisms termed diazotrophs, have evolved the ability to reduce N2 to generate NH3 in a process known as biological nitrogen fixation (BNF) catalysed by nitrogenase, an oxygen-sensitive enzyme complex. This ability presents an opportunity to improve the nutrition of crop plants, through the introduction into cereal crops of either the N fixing bacteria or the nitrogenase enzyme responsible for N fixation. This review explores three potential approaches to obtain N-fixing cereals: (a) engineering the nitrogenase enzyme to function in plant cells; (b) engineering the legume symbiosis into cereals; and (c) engineering cereals with the capability to associate with N-fixing bacteria.

A rate nephelometer for measuring specific proteins by immunoprecipitin reactions.

1977 ◽  
Vol 23 (8) ◽  
pp. 1456-1464 ◽  
Author(s):  
J C Sternberg
Keyword(s):  
Maximum Rate ◽  
Serum Proteins ◽  
Rapid Determination ◽  
Scattered Light ◽  
Single Point ◽  
Rate Of Change ◽  
Specific Proteins ◽  
Antigen Antibody ◽  
Machine Readable

Abstract A kinetic nephelometric method and instrument have been developed for the rapid determination of specific serum proteins by means of immunoprecipitin reactions. The maximum rate of change of scattered light intensity in an antigen-antibody reaction can be made to occur within 60 s after initiation of the reaction and provides a measure of the antigen concentration under antibody excess conditions. A mathematical relationship has been found for the conversion of the nonlinear maximum rate data directly into a linear concentration read-out, making possible the use of single-point calibration. Instrument operating parameters and computations are programmed for a particular analysis by means of machine-readable cards. Antigen-excess samples are detected rapidly by injection of calibrator into the reaction mixture after the rate signal has dropped to a pre-selected level. The method correlates well with both radial immunodiffusion and end-point nephelometric methods.

Improving Dryland Cropping System Nitrogen Balance with No-Tillage and Nitrogen Fertilization

2018 ◽  
Author(s):  
Upendra Sainju ◽  
Rajan Ghimire ◽  
Gautam Pradhan
Keyword(s):  
Environmental Sustainability ◽  
Cropping System ◽  
N Fertilization ◽  
N Fixation ◽  
No Tillage ◽  
Soil N ◽  
Total N ◽  
N Retention ◽  
N Removal ◽  
N Input

Studies on N balance due to N inputs and outputs and soil N retention to measure cropping system performance and environmental sustainability are limited due to the complexity of measurements of some parameters. We measured N balance based on N inputs and outputs and soil N retention under dryland agroecosystem affected by cropping system and N fertilization from 2007 to 2011 in the northern Great Plains, USA. Cropping systems were conventional tillage barley (Hordeum vulgaris L.)-fallow (CTB-F), no-tillage barley-fallow (NTB-F), no-tillage barley-pea (Pisum sativum L.) (NTB-P), and no-tillage continuous barley (NTCB). Nitrogen rates to barley were 0, 40, 80, and 120 kg N ha-1. Total N input due to N fertilization, pea N fixation, soil N mineralization, atmospheric N deposition, nonsymbiotic N fixation, and crop seed N and total N output due to grain N removal, denitrification, volatilization, N leaching, gaseous N (NOx) emissions, surface runoff, and plant senescence were 28 to 37% greater with NTB-P and NTCB than CTB-F and NTB-F. Total N input and output also increased with increased N rate. Nitrogen sequestration rate at 0 to 10 cm averaged 22 kg N ha-1 yr-1 for all treatments. Nitrogen deficit ranged from 5 to 16 kg N ha-1 yr-1, with greater deficits for CTB-F and NTB-P and higher N rates. Because of increased grain N removal and reduced N loss to the environment and N fertilizer requirement, NTB-P with 40 kg N ha-1 can enhance agronomic performance and environmental sustainability while reducing N inputs compared to other management practices.

Relationship Between N2-Fixation and Heterocyst Abundance and its Relevance to the Nitrogen Budget of Lake 227

1994 ◽  
Vol 51 (10) ◽  
pp. 2254-2266 ◽  
Author(s):  
D. L. Findlay ◽  
R. E. Hecky ◽  
L. L. Hendzel ◽  
M. P. Stainton ◽  
G. W. Regehr
Keyword(s):  
N:P Ratio ◽  
Molar Ratio ◽  
External Loading ◽  
N Fixation ◽  
Fixation Rate ◽  
Loading Rates ◽  
Relative Contribution ◽  
Cyanobacteria Blooms ◽  
N Loading ◽  
Low Nitrogen

A significant relationship between seasonal N2-fixation rate and heterocyst abundance has been found in Lake 227 and can be modelled to estimate areal rates of N2-fixation based on the known historical phytoplankton records. Experimental imposition of low nitrogen (N): phosphorus (P) loading ratios stimulated N,-fixation. The N:P molar ratio of the internal pool of nutrients oscillates around a mean of 30:1, despite experimental loading ratios that vary from 13:1 to 0. Maintenance of this internal nutrient mass ratio requires preferential regeneration of N through time at all loading rates. Heterocystous, cyanobacteria blooms are most predictable during imposition of a very low external loading N:P ratio and high P loading relative to natural sources. Knowledge of the internal loading N:P ratio and relative contribution of internal and external loadings are required for predicting blooms at intermediate external N:P loading rates. The internal N:P ratio has fluctuated within narrow limits over 25 yr of nearly constant P loading because of adjustments in N2-fixation, N sedimentation, and denitrification, which have counterbalanced changing experimental N loading regimes.

scholarly journals Nitrogen balance and fate in a heavily impacted watershed (Oglio River, Northern Italy): in quest of the missing sources and sinks

2012 ◽  
Vol 9 (1) ◽  
pp. 361-373 ◽  
Author(s):  
M. Bartoli ◽  
E. Racchetti ◽  
C. A. Delconte ◽  
E. Sacchi ◽  
E. Soana ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Nitrogen Removal ◽  
Nitrate Concentration ◽  
Isotope Composition ◽  
Northern Italy ◽  
N Budget ◽  
Channel Network ◽  
Total N ◽  
Crop Uptake ◽  
N Removal

Abstract. We present data from a comprehensive investigation carried out from 2007 to 2010, focussing on nitrogen pollution in the Oglio River basin (3800 km2, Po Plain, Northern Italy). Nitrogen mass balances, computed for the whole basin with 2000 and 2008 data, suggest a large N surplus in this area, over 40 000 t N yr−1, and increasing between 2000 and 2008. Calculations indicate a very large impact of animal husbandry and agricultural activities in this watershed, with livestock manure and synthetic fertilizers contributing 85% of total N inputs (about 100 000 t N yr−1) and largely exceeding crop uptake and other N losses (about 60 000 t N yr−1). Nitrogen from domestic and industrial origin is estimated as about 5800 and 7200 t N yr−1, respectively, although these loads are overestimated, as denitrification in treatment plants is not considered; nonetheless, they represent a minor term of the N budget. Annual export of nitrogen from the basin, calculated from flow data and water chemistry at the mouth of the Oglio River, is estimated at 13 000 t N yr−1, and represents a relatively small fraction of N inputs and surplus (∼12% and 34%, respectively). After considering N sinks in crop uptake, soil denitrification and volatilization, a large excess remains unaccounted (∼26 000 t N yr−1) in unknown temporary or permanent N sinks. Nitrogen removal via denitrification was evaluated in the Oglio riverbed with stable isotope techniques (δ15N and δ18O in nitrate). The downstream final segment of the river displays an enriched nitrate stable isotope composition but calculations suggest a N removal corresponding to at most 20% of the unaccounted for N amount. Denitrification was also evaluated in riverine wetlands with the isotope pairing technique. Areal rates are elevated but overall N removal is low (about 1% of the missing N amount), due to small wetland surfaces and limited lateral connectivity. The secondary drainage channel network has a much higher potential for nitrogen removal via denitrification, due to its great linear development, estimated in over 12 500 km, and its capillary distribution in the watershed. In particular, we estimated a maximum N loss up to 8500 t N yr−1, which represents up to 33% of the unaccounted for N amount in the basin. Overall, denitrification in surface aquatic habitats within this basin can be responsible for the permanent removal of about 12 000 t N yr−1; but the fate of some 14 000 t remains unknown. Available data on nitrate concentration in wells suggest that in the central part of the watershed groundwater accumulates nitrogen. Simultaneously, we provide evidences that part of the stored nitrate can be substantially recycled via springs and can pollute surface waters via river-groundwater interactions. This probably explains the ten fold increase of nitrate concentration in a reach of the Oglio River where no point pollutions sources are present.

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