scholarly journals Response of sedimentary processes to cyanobacteria loading

2015 ◽  
Author(s):  
Mindaugas Zilius ◽  
Rutger De Wit ◽  
Marco Bartoli
Keyword(s):  
Experimental Approach ◽  
Organic N ◽  
N Fixation ◽  
Atmospheric Nitrogen ◽  
Labile Organic Matter ◽  
Total N ◽  
Open Sea ◽  
N Fluxes ◽  
Benthic Microbial Community ◽  
N Compounds

<p>Sedimentation of pelagic cyanobacteria in dystrophic freshwater and oligohaline lagoons results in large inputs of labile organic matter (OM) to the benthos. We used an experimental approach to study the short-term impact of such phenomena on the benthic microbial community metabolism and on the nitrogen (N) fluxes across the sediment-water interface. We hypothesized an increase of respiratory activity, including N loss via denitrification and its recycling to the water column. Our results show that the incorporation within sediments of the settled bloom increases benthic bacterial activities. This is coupled to large DON and NH<sub>4</sub><sup>+</sup> effluxes, and to a comparatively smaller increase of N<sub>2</sub> production, while no significant effects were detected for the benthic fluxes of NO<sub>x</sub><sup>-</sup>. We constructed flow schemes for N compounds, which show that while denitrification was significantly stimulated by amending cyanobacterial biomass to the sediments, it represented less than 1% of total OM mineralization. Interestingly, we observed that total released nitrogen (DIN+DON+N<sub>2</sub> efflux) was dominated by DON, which contributed 75–80 % of the net N efflux, suggesting incomplete mineralization of OM. With the measured total N mobilization rate of about 15 mmol N m<sup>-2</sup> d<sup>-1</sup> it would take more than 4 months to regenerate the total organic N input to sediments (2031 mmol N m<sup>-2</sup>), which represents the post-bloom deposited particulate organic N. These results suggest limited losses to the atmosphere and slow diffusive recycling of N buried into sediments, mostly as DON. Such regenerated N may eventually be flushed to the open sea or sustain pelagic blooms within the estuarine environment, including cyanobacteria, with a negative feedback for further import of atmospheric nitrogen via N-fixation.</p>

scholarly journals The changes of soil nitrogen and carbon contents in a long-term field experiment under different systems of nitrogen fertilization

2008 ◽  
Vol 54 (No. 11) ◽  
pp. 463-470 ◽  
Author(s):  
V. Nedvěd ◽  
J. Balík ◽  
J. Černý ◽  
M. Kulhánek ◽  
M. Balíková
Keyword(s):  
Field Experiment ◽  
N Fertilization ◽  
Hot Water ◽  
Control Treatment ◽  
Organic N ◽  
Total N ◽  
C And N ◽  
N Compounds ◽  
Term Field

Content of N and C in soil were investigated in a long-term field experiment under different systems of N fertilization. Chernozem and Cambisol were extracted using hot water (N<sub>hws</sub>, C<sub>hws</sub>) and 0.01M CaCl<sub>2</sub> (N<sub>CaCl2</sub>, C<sub>DOC</sub>). The C<sub>t</sub>/N<sub>t</sub> ratio in Chernozem was 9.6:1 and in Cambisol 6.1:1. The lowest C<sub>t</sub>/N<sub>t</sub> ratio in both experiments was found in the control treatment. Results showed that C and N compounds are less stable in Cambisol, which leads to a higher rate of mineralization. In the Chernozem, N<sub>hws</sub> formed 3.66% from the total N content in the soil whereas N<sub>CaCl2</sub> formed only 0.82%. C<sub>hws</sub> formed 2.98% and C<sub>DOC</sub> 0.34% from total C content. Cambisol contains 4.81% of N<sub>hws</sub> and 0.84% of N<sub>CaCl2</sub> from the total N amount and 5.76% of C<sub>hws</sub> and 0.70% of C<sub>DOC</sub> from the total C content, respectively. Nitrogen extracted by 0.01M CaCl2 formed only 22.4% of N extractable by hot water in Chernozem and 17.5% in Cambisol. The lowest C/N ratios were obtained after the CaCl<sub>2</sub> extraction (3.0–6.2:1). The application of manure increased the content of soil organic N and C compared to the sewage sludge treatments.

scholarly journals Water and nitrogen processes along a typical water flowpath and streamwater exports from a forested catchment and changes after clear-cutting: a modelling study

2005 ◽  
Vol 9 (6) ◽  
pp. 657-674 ◽  
Author(s):  
A. Laurén ◽  
L. Finér ◽  
H. Koivusalo ◽  
T. Kokkonen ◽  
T. Karvonen ◽  
...  
Keyword(s):  
Buffer Zone ◽  
Organic N ◽  
Ground Vegetation ◽  
Spring Flood ◽  
Total N ◽  
Clear Cut ◽  
Clear Cutting ◽  
N Fluxes ◽  
Before And After ◽  
Eastern Finland

Abstract. A two dimensional model, FEMMA, to describe water and nitrogen (N) fluxes within and from a forested first-order catchment (Kangasvaara in Eastern Finland) was constructed by linking the most significant processes affecting the fluxes of water, ammonium, nitrate and dissolved organic nitrogen along a hillslope from the water divide to the stream. The hillslope represents the average flowpath of water in the catchment and the model was used to estimate the N fluxes for a catchment in eastern Finland before and after clear-cutting. The simulated results were in reasonable agreement with the nitrate, dissolved organic N and dissolved total N measurements from the study catchment and with other results in the literature. According to the simulations, the major sinks of N after clear-cutting were immobilisation by soil microbes, uptake by ground vegetation and sorption to soil. These sinks increased downslope from the clear-cut area, indicating the importance of an uncut buffer zone between the stream and the clear-cut area in reducing N exports. The buffer zone retained 76% of the N flux coming from the clear-cut area. Nitrification was a key process in controlling the N export after clear-cutting and N increases were mainly as nitrate. Most of the annual N export took place during the spring flood, when uptake of N by plants was minimal.

scholarly journals Leucaena leucocephala introduction into a tropical pasture in the Chaco region of Argentina. Effects on soil carbon and total nitrogen

2019 ◽  
Vol 7 (4) ◽  
pp. 295-302
Author(s):  
Natalia Banegas ◽  
Roberto Corbella ◽  
Emilce Viruel ◽  
Adriana Plasencia ◽  
Belen Roig ◽  
...  
Keyword(s):  
Soil Fertility ◽  
Leucaena Leucocephala ◽  
Greenhouse Gas Mitigation ◽  
Organic N ◽  
N Fixation ◽  
Stable Form ◽  
Limited Information ◽  
Total N ◽  
Chaco Region ◽  
Grass Growth

Keynote paper presented at the International Leucaena Conference, 1‒3 November 2018, Brisbane, Queensland, Australia.The introduction of leucaena (Leucaena leucocephala), apart from increasing animal production, improves soil fertility through biological nitrogen (N) fixation and its deep-rooted system. There is limited information on carbon and N dynamics in hedgerow silvopastoral systems, particularly in the subsoil profile. The concentrations and vertical distribution of organic carbon (OC) and total N , and their fractions (particulate and associate forms) in the profile (0‒100 cm) of a 4-year-old leucaena stand in a Urochloa brizantha-Chloris gayana pasture were compared with those in the adjacent pure tropical grass (U. brizantha) pasture. Leucaena introduction increased the OC concentration in the subsoil (20‒100 cm) by 45%, particularly the stable form (associate OC) in the deepest horizon (50‒100 cm). This was attributed to a greater abundance of leucaena roots deeper in the profile than for grass. Leucaena also enhanced by 7.6% the N concentration (from 0.131 to 0.141%) in the topsoil (0‒20 cm) associated with an increment in the labile form (particulate organic N), due to leaf deposition, recycling of animal feces and nodule-N turnover from N fixation. Leucaena establishment has the potential to improve soil fertility and hence availability of N to companion grass growth, and can be utilized as a greenhouse gas mitigation strategy.

scholarly journals Organic Nitrogen in Precipitation: Real Problem or Sampling Artefact?

2001 ◽  
Vol 1 ◽  
pp. 230-237 ◽  
Author(s):  
J.N. Cape ◽  
A. Kirika ◽  
A.P. Rowland ◽  
D.R. Wilson ◽  
T.D. Jickells ◽  
...  
Keyword(s):  
Organic Nitrogen ◽  
Sampling Methods ◽  
Organic N ◽  
Real Problem ◽  
Chemical Analyses ◽  
Total N ◽  
Ionic Concentrations ◽  
Set Up ◽  
And Storage ◽  
N Compounds

Published observations of organic nitrogen (N) compounds in precipitation go back almost a century. Several different methods have been used to measure both the total and ionic concentrations of N. There is therefore some uncertainty as to whether reported �organic N� is real, or simply the result of uncertainties in chemical analyses or inadequate sampling methods. We found that the materials from which the collector was made (polypropylene, steel, or glass) had no significant effect on the composition of dissolved organic N (DON). The use of a biocide was found to be very important during sampling and storage of samples before analysis. We set up a network of seven collectors across the U.K., from the Cairngorms to Dorset, all operating to the same protocol, and including a biocide. Samples were analysed centrally, using proven methods. Over 6 months, organic N contributed about 20% to the total N in U.K. precipitation, but with a large variation across the country. This means that current estimates of wet deposited N to the U.K., which are based only on the ammonium and nitrate concentrations, are too small. Organic N is not an artefact, but a real problem that needs to be addressed.

scholarly journals Nitrogen fertilizer value of animal slurries with different proportions of liquid and solid fractions: A 3-year study under field conditions

2021 ◽  
pp. 1-11
Author(s):  
Betina Nørgaard Pedersen ◽  
Bent T. Christensen ◽  
Luca Bechini ◽  
Daniele Cavalli ◽  
Jørgen Eriksen ◽  
...  
Keyword(s):  
Solid Fraction ◽  
Liquid Fraction ◽  
N Fertilizer ◽  
Organic N ◽  
First Year ◽  
Net N Mineralization ◽  
Pig Slurry ◽  
Total N ◽  
Plant Availability ◽  
Loamy Sand Soil

Abstract The plant availability of manure nitrogen (N) is influenced by manure composition in the year of application whereas some studies indicate that the legacy effect in following years is independent of the composition. The plant availability of N in pig and cattle slurries with variable contents of particulate matter was determined in a 3-year field study. We separated cattle and a pig slurry into liquid and solid fractions by centrifugation. Slurry mixtures with varying proportions of solid and liquid fraction were applied to a loamy sand soil at similar NH4+-N rates in the first year. Yields and N offtake of spring barley and undersown perennial ryegrass were compared to plots receiving mineral N fertilizer. The first year N fertilizer replacement value (NFRV) of total N in slurry mixtures decreased with increasing proportion of solid fraction. The second and third season NFRV averaged 6.5% and 3.8% of total N, respectively, for cattle slurries, and 18% and 7.5% for pig slurries and was not related to the proportion of solid fraction. The estimated net N mineralization of residual organic N increased nearly linearly with growing degree days (GDD) with a rate of 0.0058%/GDD for cattle and 0.0116%/GDD for pig slurries at 2000–5000 GDD after application. In conclusion NFRV of slurry decreased with increasing proportion of solid fraction in the first year. In the second year, NFRV of pig slurry N was significantly higher than that of cattle slurry N and unaffected by proportion between solid and liquid fraction.

scholarly journals Effects of two wood-based biochars on the fate of added fertilizer nitrogen—a 15N tracing study

2021 ◽  
Author(s):  
Subin Kalu ◽  
Gboyega Nathaniel Oyekoya ◽  
Per Ambus ◽  
Priit Tammeorg ◽  
Asko Simojoki ◽  
...  
Keyword(s):  
Plant Uptake ◽  
Plant Biomass ◽  
Application Rate ◽  
Control Treatment ◽  
Organic N ◽  
N Leaching ◽  
Soil N ◽  
Mineral N ◽  
Total N ◽  
Application Rates

AbstractA 15N tracing pot experiment was conducted using two types of wood-based biochars: a regular biochar and a Kon-Tiki-produced nutrient-enriched biochar, at two application rates (1% and 5% (w/w)), in addition to a fertilizer only and a control treatment. Ryegrass was sown in pots, all of which except controls received 15N-labelled fertilizer as either 15NH4NO3 or NH415NO3. We quantified the effect of biochar application on soil N2O emissions, as well as the fate of fertilizer-derived ammonium (NH4+) and nitrate (NO3−) in terms of their leaching from the soil, uptake into plant biomass, and recovery in the soil. We found that application of biochars reduced soil mineral N leaching and N2O emissions. Similarly, the higher biochar application rate of 5% significantly increased aboveground ryegrass biomass yield. However, no differences in N2O emissions and ryegrass biomass yields were observed between regular and nutrient-enriched biochar treatments, although mineral N leaching tended to be lower in the nutrient-enriched biochar treatment than in the regular biochar treatment. The 15N analysis revealed that biochar application increased the plant uptake of added nitrate, but reduced the plant uptake of added ammonium compared to the fertilizer only treatment. Thus, the uptake of total N derived from added NH4NO3 fertilizer was not affected by the biochar addition, and cannot explain the increase in plant biomass in biochar treatments. Instead, the increased plant biomass at the higher biochar application rate was attributed to the enhanced uptake of N derived from soil. This suggests that the interactions between biochar and native soil organic N may be important determinants of the availability of soil N to plant growth.

scholarly journals Evidence of Phosphate Mining and Agriculture Influence on Concentrations, Forms, and Ratios of Nitrogen and Phosphorus in a Florida River

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1064
Author(s):  
Shuiwang Duan ◽  
Kamaljit Banger ◽  
Gurpal S. Toor
Keyword(s):  
Agricultural Land ◽  
Water Discharge ◽  
Mining Area ◽  
Specific Conductance ◽  
Organic N ◽  
Wet Season ◽  
Nitrogen And Phosphorus ◽  
Total N ◽  
Phosphate Mining ◽  
Molar Ratios

Florida has a long history of phosphate-mining, but less is known about how mining affects nutrient exports to coastal waters. Here, we investigated the transport of inorganic and organic forms of nitrogen (N) and phosphorus (P) over 23 sampling events during a wet season (June–September) in primary tributaries and mainstem of Alafia River that drains into the Tampa Bay Estuary. Results showed that a tributary draining the largest phosphate-mining area (South Prong) had less flashy peaks, and nutrients were more evenly exported relative to an adjacent tributary (North Prong), highlighting the effectiveness of the mining reclamation on stream hydrology. Tributaries draining > 10% phosphate-mining area had significantly higher specific conductance (SC), pH, dissolved reactive P (DRP), and total P (TP) than tributaries without phosphate-mining. Further, mean SC, pH, and particulate reactive P were positively correlated with the percent phosphate-mining area. As phosphate-mining occurred in the upper part of the watershed, the SC, pH, DRP, and TP concentrations increased downstream along the mainstem. For example, the upper watershed contributed 91% of TP compared to 59% water discharge to the Alafia River. In contrast to P, the highest concentrations of total N (TN), especially nitrate + nitrite (NOx–N) occurred in agricultural tributaries, where the mean NOx–N was positively correlated with the percent agricultural land. Dissolved organic N was dominant in all streamwaters and showed minor variability across sites. As a result of N depletion and P enrichment, the phosphate-mining tributaries had significantly lower molar ratios of TN:TP and NOx–N:DRP than other tributaries. Bi-weekly monitoring data showed consistent increases in SC and DRP and a decrease in NOx–N at the South Prong tributary (highest phosphate-mining area) throughout the wet season, and different responses of dissolved inorganic nutrients (negative) and particulate nutrients (positive) to water discharge. We conclude that (1) watersheds with active and reclaimed phosphate-mining and agriculture lands are important sources of streamwater P and N, respectively, and (2) elevated P inputs from the phosphate-mining areas altered the N:P ratios in streamwaters of the Alafia River.

Characteristics of Non-Point Source N Export via Surface Runoff from Sloping Croplands in Northeast China

2011 ◽  
Vol 347-353 ◽  
pp. 2302-2307 ◽  
Author(s):  
Hong Xiang Wang ◽  
Yi Shi ◽  
Jian Ma ◽  
Cai Yan Lu ◽  
Xin Chen
Keyword(s):  
Point Source ◽  
Surface Runoff ◽  
Rainfall Intensity ◽  
Inorganic Nitrogen ◽  
Rainfall Amount ◽  
Organic N ◽  
Dissolved Inorganic Nitrogen ◽  
Slope Gradient ◽  
N Loss ◽  
Total N

A field experiment was conducted to study the characteristics of non-point source nitrogen (N) in the surface runoff from sloping croplands and the influences of rainfall and cropland slope gradient. The results showed that dissolved total N (DTN) was the major form of N in the runoff, and the proportion occupied by dissolved inorganic nitrogen (DIN) ranged from 45% to 85%. The level of NH4+-N was generally higher than the level of NO3--N, and averaged at 2.50 mg·L-1and 1.07 mg·L-1respectively. DIN was positively correlated with DTN (R2=0.962). Dissolved organic N (DON) presented a moderate seasonal change and averaged at 1.40 mg·L-1. Rainfall amount and rainfall intensity significantly affected the components of DTN in the runoff. With the increase of rainfall amount and rainfall intensity, the concentrations of DTN, NH4+-N and NO3--N presented a decreased trend, while the concentration of DON showed an increased trend. N loss went up with an increase in the gradient of sloping cropland, and was less when the duration was longer from the time of N fertilization.fertilization.

scholarly journals The soil N cycle: new insights and key challenges

SOIL ◽  
2015 ◽  
Vol 1 (1) ◽  
pp. 235-256 ◽  
Author(s):  
J. W. van Groenigen ◽  
D. Huygens ◽  
P. Boeckx ◽  
Th. W. Kuyper ◽  
I. M. Lubbers ◽  
...  
Keyword(s):  
N Cycling ◽  
Greenhouse Gas Mitigation ◽  
Future Research ◽  
N Fixation ◽  
Gaseous Emissions ◽  
Soil N ◽  
Personal View ◽  
Total N ◽  
N Cycle ◽  
Soil N Cycle

Abstract. The study of soil N cycling processes has been, is, and will be at the centre of attention in soil science research. The importance of N as a nutrient for all biota; the ever-increasing rates of its anthropogenic input in terrestrial (agro)ecosystems; its resultant losses to the environment; and the complexity of the biological, physical, and chemical factors that regulate N cycling processes all contribute to the necessity of further understanding, measuring, and altering the soil N cycle. Here, we review important insights with respect to the soil N cycle that have been made over the last decade, and present a personal view on the key challenges of future research. We identify three key challenges with respect to basic N cycling processes producing gaseous emissions: 1. quantifying the importance of nitrifier denitrification and its main controlling factors; 2. characterizing the greenhouse gas mitigation potential and microbiological basis for N2O consumption; 3. characterizing hotspots and hot moments of denitrification Furthermore, we identified a key challenge with respect to modelling: 1. disentangling gross N transformation rates using advanced 15N / 18O tracing models Finally, we propose four key challenges related to how ecological interactions control N cycling processes: 1. linking functional diversity of soil fauna to N cycling processes beyond mineralization; 2. determining the functional relationship between root traits and soil N cycling; 3. characterizing the control that different types of mycorrhizal symbioses exert on N cycling; 4. quantifying the contribution of non-symbiotic pathways to total N fixation fluxes in natural systems We postulate that addressing these challenges will constitute a comprehensive research agenda with respect to the N cycle for the next decade. Such an agenda would help us to meet future challenges on food and energy security, biodiversity conservation, water and air quality, and climate stability.

scholarly journals Makro- és mikroelem-tartalom összehasonlítása almaültetvények talajában

2005 ◽  
Vol 54 (3-4) ◽  
pp. 389-402 ◽  
Author(s):  
Péter Tamás Nagy
Keyword(s):  
Humus Content ◽  
Active Agent ◽  
Apple Orchard ◽  
Organic Manure ◽  
Organic N ◽  
Nutrient Concentrations ◽  
Apple Orchards ◽  
Total N ◽  
Significant Difference ◽  
Organic Orchards

In a three-year study carried out at the Debrecen-Pallagi nursery of the University of Debrecen, the nutrient contents, humus content and pH of the soil were determined in integrated and organic apple orchards established on brown forest soil with thin interstratified layers of colloid and sesquioxide accumulation. The organic orchard was only given organic manure (50 t/ha) in spring 2000 and 2002, while the integrated orchard was treated with 250 kg/ha complex NPK fertilizer (16.5-16.5-16.5) every year between 1997 and 2003 after the leaves had fallen. An additional 50 kg/ha N active agent as NH 4 NO 3 was applied every year, while 4 t/ha lime fertilizer (carbonation mud) was provided in autumn 2002 and 25 t/ha organic manure in November 2003. In 2004 no fertilizer was given to either orchard. The available forms of N (NO 3- , NH 4+ , organic N and total N) and P (ortho-, organic and total-PO 43- ) were determined after extraction with 0.01 M CaCl 2 , while the Ca, Mg and microelement (Mn, Cu, Zn) content of the soil was extracted with NH 4 -acetate +EDTA (Lakanen-Erviö extractant). Potassium was measured in both extractants. The results showed that the inorganic, organic and total soluble nitrogen in the soil were significantly higher (P = 0.05) in the integrated orchard than in the organic one. It was found that the quantity and ratio of the organic N fraction was comparable with that of the inorganic N forms. The ortho- phosphate and total P fractions were significantly higher (P = 0.05) in the integrated apple orchard than in the organic orchard, while there was no significant difference in the organic P quantity. The potassium data showed that both the integrated and organic orchards contained a satisfactory amount of adsorbed K in spite of the poor colloid content and high soil acidity. The Ca, Mg, Co and Zn contents of the integrated soils were significantly higher (P = 0.05) than in the organic orchard. For Mn, however, no substantial difference was found between the integrated and organic orchards. With the exception of Mn, the nutrient concentrations reflected the differences in the nutrient management of the integrated and organic apple orchards.

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