Modelling DCD effect on nitrate leaching under controlled conditions

Soil Research ◽  
2007 ◽  
Vol 45 (4) ◽  
pp. 310 ◽  
Author(s):  
Iris Vogeler ◽  
Adeline Blard ◽  
Nanthi Bolan
Keyword(s):  
Nitrate Leaching ◽  
Nitrification Inhibitor ◽  
Life Time ◽  
Potential Effect ◽  
Nitrification Rate ◽  
Nitrogen Transformations ◽  
Column Leaching ◽  
Loam Soil ◽  
Leaching Experiments ◽  
The Difference

Effects of nitrogen losses through nitrate leaching are one of the major environmental issues worldwide. To determine the potential effect of dicyandiamide (DCD), a nitrification inhibitor, on the transformation of urea nitrogen and subsequent nitrate leaching, incubation and column leaching experiments were performed. Tokomaru silt loam soil was treated with urea, DCD, or urea plus DCD. A control was also used. In the laboratory incubation experiment, the conversion of urea to ammonium (i.e. ammonification process or urea hydrolysis) occurred within a day, thereby increasing the soil pH from 5.8 to 6.9. DCD did not affect the ammonification process. However, DCD did slow down the subsequent oxidation of ammonium to nitrate (i.e. nitrification process). The half-life time of ammonium in this soil was increased from 9 days for the urea treatment to 31 days for the urea + DCD treatment. The production of nitrate was 5 times slower when DCD was added. In the leaching experiments, half the columns were leached after 1 day of incubation (Day 1), the other half 7 days later (Day 7). For Day 1, no significant differences in nitrate leaching could be seen between the treatments, as the nitrification had not yet taken place. For Day 7, DCD decreased nitrate leaching by 71% with a corresponding decrease in nitrate-induced cation leaching, including ammonium. Thus, DCD seems to be effective in decreasing both ammonium and nitrate leaching, but its high solubility and thus mobility could be a limitation to its use. The convection–dispersion equation, including source–sink terms for nitrogen transformations, ammonification, and nitrification rate constants, and a factor for nitrification inhibition by DCD, accounting for degradation and efficiency of DCD, could be used reasonably well to simulate nitrate leaching from the column leaching experiments. However, model parameter values for nitrification rate, and efficiency and decay rate for DCD, were different from those obtained from the incubation experiments, which was probably because of the difference in water content of soil between the incubation and leaching experiments.

Effects of temperature and application rate of a nitrification inhibitor, dicyandiamide (DCD), on nitrification rate and microbial biomass in a grazed pasture soil

Soil Research ◽  
2004 ◽  
Vol 42 (8) ◽  
pp. 927 ◽  
Author(s):  
H. J. Di ◽  
K. C. Cameron
Keyword(s):  
Microbial Biomass ◽  
Soil Temperature ◽  
Nitrate Leaching ◽  
Half Life ◽  
Soil Microbial Biomass ◽  
Nitrification Inhibitor ◽  
Application Rate ◽  
Nitrification Rate ◽  
Soil Microbial ◽  
Grazed Pasture

Abstract. The nitrification inhibitor dicyandiamide (DCD) has recently been shown to be effective in reducing nitrate leaching from grazed pasture soils. The objective of this study was to determine the influence of temperature and application rate on the effectiveness of DCD in nitrification inhibition. Possible effects on soil microbial biomass were also determined. The soil, Lismore silt loam (Pallic orthic brown soil; Udic Haplustept loamy skeletal), was incubated at a moisture content near field capacity under 2 temperatures (8 or 20°C). Urea was applied at 25 kg N/ha and dairy cow urine at 1000 kg N/ha. DCD was applied at 2 rates equivalent to 7.5 or 15 kg/ha. The results show that at a soil temperature of 8°C, the half-life of DCD was 111–116 days. The half-life of NH4+ changed from 44 days without DCD to 243–491 days when DCD was applied. In contrast, at a soil temperature of 20°C the half-life of DCD was 18–25 days. The half-life of NH4+ changed from 22 days without DCD to 64–55 days with DCD. The 2 different rates of DCD had a small effect on the NH4+ concentration in the soil. The application of DCD did not have a significant effect on soil microbial biomass. DCD would therefore be most effective in inhibiting nitrification and thus reducing nitrate leaching in late autumn–winter–early spring in most parts of New Zealand when daily average soil temperatures are generally below 10°C and when drainage is high.

NITROGEN TRANSFORMATIONS NEAR UREA IN SOIL WITH DIFFERENT WATER POTENTIALS

1988 ◽  
Vol 68 (3) ◽  
pp. 569-576 ◽  
Author(s):  
YADVINDER SINGH ◽  
E. G. BEAUCHAMP
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Incubation Period ◽  
Relative Rate ◽  
Soil Water Potential ◽  
Nitrification Inhibitor ◽  
Silt Loam ◽  
Nitrogen Transformations ◽  
Water Potentials ◽  
Initial Soil

Two laboratory incubation experiments were conducted to determine the effect of initial soil water potential on the transformation of urea in large granules to nitrite and nitrate. In the first experiment two soils varying in initial soil water potentials (− 70 and − 140 kPa) were incubated with 2 g urea granules with and without a nitrification inhibitor (dicyandiamide) at 15 °C for 35 d. Only a trace of [Formula: see text] accumulated in a Brookston clay (pH 6.0) during the transformation of urea in 2 g granules. Accumulation of [Formula: see text] was also small (4–6 μg N g−1) in Conestogo silt loam (pH 7.6). Incorporation of dicyandiamide (DCD) into the urea granule at 50 g kg−1 urea significantly reduced the accumulation of [Formula: see text] in this soil. The relative rate of nitrification in the absence of DCD at −140 kPa water potential was 63.5% of that at −70 kPa (average of two soils). DCD reduced the nitrification of urea in 2 g granules by 85% during the 35-d period. In the second experiment a uniform layer of 2 g urea was placed in the center of 20-cm-long cores of Conestogo silt loam with three initial water potentials (−35, −60 and −120 kPa) and the soil was incubated at 15 °C for 45 d. The rate of urea hydrolysis was lowest at −120 kPa and greatest at −35 kPa. Soil pH in the vicinity of the urea layer increased from 7.6 to 9.1 and [Formula: see text] concentration was greater than 3000 μg g−1 soil. There were no significant differences in pH or [Formula: see text] concentration with the three soil water potential treatments at the 10th day of the incubation period. But, in the latter part of the incubation period, pH and [Formula: see text] concentration decreased with increasing soil water potential due to a higher rate of nitrification. Diffusion of various N species including [Formula: see text] was probably greater with the highest water potential treatment. Only small quantities of [Formula: see text] accumulated during nitrification of urea – N. Nitrification of urea increased with increasing water potential. After 35 d of incubation, 19.3, 15.4 and 8.9% of the applied urea had apparently nitrified at −35, −60 and −120 kPa, respectively. Nitrifier activity was completely inhibited in the 0- to 2-cm zone near the urea layer for 35 days. Nitrifier activity increased from an initial level of 8.5 to 73 μg [Formula: see text] in the 3- to 7-cm zone over the 35-d period. Nitrifier activity also increased with increasing soil water potential. Key words: Urea transformation, nitrification, water potential, large granules, nitrifier activity, [Formula: see text] production

scholarly journals Soil gross nitrogen transformations in forestland and cropland of Regosols

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xiao Ren ◽  
Jinbo Zhang ◽  
Hamidou Bah ◽  
Christoph Müller ◽  
Zucong Cai ◽  
...  
Keyword(s):  
Land Use ◽  
Southwest China ◽  
Nitrification Rate ◽  
Land Uses ◽  
Nitrogen Transformations ◽  
N Losses ◽  
Retention Capacity ◽  
N Transformations ◽  
Autotrophic Nitrification ◽  
Land Use Types

AbstractSoil gross nitrogen (N) transformations could be influenced by land use change, however, the differences in inherent N transformations between different land use soils are still not well understood under subtropical conditions. In this study, an 15N tracing experiment was applied to determine the influence of land uses on gross N transformations in Regosols, widely distributed soils in Southwest China. Soil samples were taken from the dominant land use types of forestland and cropland. In the cropland soils, the gross autotrophic nitrification rates (mean 14.54 ± 1.66 mg N kg−1 day−1) were significantly higher, while the gross NH4+ immobilization rates (mean 0.34 ± 0.10 mg N kg−1 day−1) were significantly lower than those in the forestland soils (mean 1.99 ± 0.56 and 6.67 ± 0.74 mg N kg−1 day−1, respectively). The gross NO3− immobilization and dissimilatory NO3− reduction to NH4+ (DNRA) rates were not significantly different between the forestland and cropland soils. In comparison to the forestland soils (mean 0.51 ± 0.24), the cropland soils had significantly lower NO3− retention capacities (mean 0.01 ± 0.01), indicating that the potential N losses in the cropland soils were higher. The correlation analysis demonstrated that soil gross autotrophic nitrification rate was negatively and gross NH4+ immobilization rate was positively related to the SOC content and C/N ratio. Therefore, effective measures should be taken to increase soil SOC content and C/N ratio to enhance soil N immobilization ability and NO3− retention capacity and thus reduce NO3− losses from the Regosols.

scholarly journals The Influence of Mineral Fertilizer Combined With a Nitrification Inhibitor on Microbial Populations and Activities in Calcareous Uzbekistanian Soil Under Cotton Cultivation

2001 ◽  
Vol 1 ◽  
pp. 108-113 ◽  
Author(s):  
Dilfuza Egamberdiyeva ◽  
Muhiddin Mamiev ◽  
Svetlana K. Poberejskaya
Keyword(s):  
Nitrification Inhibitor ◽  
Mineral Fertilizer ◽  
Denitrifying Bacteria ◽  
Nitrifying Bacteria ◽  
Most Probable Number ◽  
Nitrification Rate ◽  
Nitrification Inhibitors ◽  
Probable Number ◽  
Soil Microbial ◽  
Soil Microbial Population

Application of fertilizers combined with nitrification inhibitors affects soil microbial biomass and activity. The objective of this research was to determine the effects of fertilizer application combined with the nitrification inhibitor potassium oxalate (PO) on soil microbial population and activities in nitrogen-poor soil under cotton cultivation in Uzbekistan. Fertilizer treatments were N as urea, P as ammophos, and K as potassium chloride. The nitrification inhibitor PO was added to urea and ammophos at the rate of 2%. Three treatments—N200P140K60(T1), N200P140 POK60(T2), and N200P140 POK60(T3) mg kg-1soil—were applied for this study. The control (C) was without fertilizer and PO. The populations of oligotrophic bacteria, ammonifying bacteria, nitrifying bacteria, denitrifying bacteria, mineral assimilating bacteria, oligonitrophilic bacteria, and bacteria group Azotobacter were determined by the most probable number method. The treatments T2 and T3 increased the number of oligonitrophilic bacteria and utilization mineral forms of nitrogen on the background of reducing number of ammonifying bacteria. T2 and T3 also decreased the number of nitrifying bacteria, denitrifying bacteria, and net nitrification. In conclusion, our experiments showed that PO combined with mineral fertilizer is one of the most promising compounds for inhibiting nitrification rate, which was reflected in the increased availability and efficiency of fertilizer nitrogen to the cotton plants. PO combined with mineral fertilizer has no negative effects on nitrogen-fixing bacteria Azotobacter and oligo-nitrophilic bacteria.

scholarly journals Dissipation of nitrapyrin (nitrification inhibitor) in subtropical soils

2019 ◽  
Vol 52 (2) ◽  
pp. 173
Author(s):  
Anjana Srivastava
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Quantitative Analysis ◽  
Environmental Pollution ◽  
Nitrate Leaching ◽  
High Performance ◽  
Nitrification Inhibitor ◽  
Quechers Method ◽  
Subtropical Soils ◽  
Nitrification Process

<p>Nitrapyrin (2-chloro-6-(trichloromethyl)pyridine) is a specific nitrifiation inhibitor, applied in soils for reducing the nitrification process of nitrogenous fertilizers. The overall effect of nitrapyrin is enhancing the efficiency of nitrogenous fertilizers in soils and also controlling environmental pollution in water by preventing nitrate leaching in soils. Dissipation of nitrapyrin was evaluated in subtropical soils at two fortification levels of 2 and 4 µg∙g-1. The extraction of nitrapyrin was done by quick, easy, cheap, rugged and safe (QuEChERS) method and quantitative analysis – by high-performance liquid chromatography (HPLC). Nitrapyrin residues declined consistently with time in both types of soils and were not detectable (</p>

scholarly journals Amikacin or Vancomycin Exposure Alters the Postnatal Serum Creatinine Dynamics in ELBW Neonates

2020 ◽  
Author(s):  
Tamara van Donge ◽  
Anne Smits ◽  
John van den Anker ◽  
Karel Allegaert
Keyword(s):  
Serum Creatinine ◽  
Potential Effect ◽  
Mixed Effects ◽  
Treatment Modalities ◽  
Antibiotic Exposure ◽  
Modelling Analysis ◽  
Sensitive Tool ◽  
Elbw Neonates ◽  
The Difference ◽  
The Impact

Background: Disentangling adverse drug reactions from confounders remains a major challenge to assess causality and severity in neonates. Vancomycin and amikacin are perceived as nephrotoxic and often prescribed in neonates. We selected these compounds to assess their impact on creatinine dynamics as sensitive tool to detect a renal impairment signal. Methods: A recently developed dynamical model that characterized serum creatinine concentrations of 217 ELBW neonates (4036 serum creatinine observations) was enhanced with data on individual administration of vancomycin and/or amikacin to identify a potential effect of antibiotic exposure by nonlinear mixed-effects modelling analysis. Results: Of our ELBW patients, 77% were exposed to either vancomycin or amikacin. Antibiotic exposure resulted in transient lower overall creatinine clearance and a modest increase in serum creatinine. Dependency on gestational age was observed in the difference in serum creatinine when exposed to antibiotics during the third week after birth (difference in creatinine for a neonate at 24 weeks gestation decreased with 56% for a 32-week-old neonate). Conclusions: A previously described model on creatinine dynamics was used to explore and quantify the impact amikacin or vancomycin exposure on creatinine dynamics. Such tools can be used to explore minor changes, or compare minor differences between treatment modalities.

scholarly journals Investigating the Effect of Three Nitrate Fertilizers on Nitrate Leaching under the Root Zone in Clay Loam Soil

2009 ◽  
Vol 5 (3) ◽  
pp. 387-392
Author(s):  
Thamer Ahmed Mohammed ◽  
M. Nooshin ◽  
Megat Johari Megat M Noor ◽  
A. Liaghat
Keyword(s):  
Nitrate Leaching ◽  
Root Zone ◽  
Clay Loam ◽  
Clay Loam Soil ◽  
Loam Soil

Spinal-pelvic orientation: potential effect on the diagnosis of spondyloarthritis

Rheumatology ◽  
2019 ◽  
Vol 59 (1) ◽  
pp. 84-89 ◽  
Author(s):  
Guillermo Carvajal Alegria ◽  
Lucile Deloire ◽  
Marion Herbette ◽  
Florent Garrigues ◽  
Laure Gossec ◽  
...  
Keyword(s):  
Back Pain ◽  
Lumbar Lordosis ◽  
Clinical Presentation ◽  
Imaging Study ◽  
Potential Effect ◽  
Inflammatory Back Pain ◽  
Recent Onset ◽  
Horizontal Angle ◽  
The Difference ◽  
Spine Radiographs

Abstract Objective To assess associations of spinal-pelvic orientation with clinical and imaging-study findings suggesting axial SpA (axSpA) in patients with recent-onset inflammatory back pain. Methods Spinal-pelvic orientation was assessed in DESIR cohort patients with recent-onset inflammatory back pain and suspected axSpA, by using lateral lumbar-spine radiographs to categorize sacral horizontal angle (&lt;40° vs ⩾40°), lumbosacral angle (&lt;15° vs ⩾15°) and lumbar lordosis (LL, &lt;50° vs ⩾50°). Associations between these angle groups and variables collected at baseline and 2 years later were assessed using the χ2 test (or Fisher's exact) and the Mann–Whitney test. With Bonferroni’s correction, P &lt; 0.001 indicated significant differences. Results Of 362 patients, 358, 356 and 357 had available sacral horizontal angle, lumbosacral angle and LL values, respectively; means were 39.3°, 14.6° and 53.0°, respectively. The prevalence of sacroiliitis on both radiographs and MRI was higher in the LL &lt; 50° group than in the LL ⩾50° group, but the difference was not statistically significant. Clinical presentation and confidence in a diagnosis of axSpA did not differ across angle groups. No significant differences were identified for degenerative changes according to sacral horizontal angle, lumbosacral angle or LL. Conclusion Spinal-pelvic balance was not statistically associated with the clinical or imaging-study findings suggesting axSpA in patients with recent-onset inflammatory back pain.

Nitrate Leaching in a Tile-Drained Silt Loam Soil

2000 ◽  
Vol 64 (2) ◽  
pp. 517-527 ◽  
Author(s):  
J. A. de Vos ◽  
D. Hesterberg ◽  
P. A. C. Raats
Keyword(s):  
Nitrate Leaching ◽  
Silt Loam ◽  
Silt Loam Soil ◽  
Loam Soil

Nitrate leaching from a drained, sheep-grazed pasture. II. Modelling nitrate leaching losses

Soil Research ◽  
1998 ◽  
Vol 36 (6) ◽  
pp. 963 ◽  
Author(s):  
R. E. White ◽  
L. K. Heng ◽  
G. N. Magesan
Keyword(s):  
Nitrate Leaching ◽  
Preferential Flow ◽  
Pulse Input ◽  
Grazed Pasture ◽  
Sink Term ◽  
Chloride Leaching ◽  
Loam Soil ◽  
Rain Events ◽  
Transport Volume ◽  
Source Sink

Nitrate (NO-3 ) concentrations in 0·5-mm increments of drainage from adjacent mole- and pipe-drained paddocks of a silt loam soil under pasture near Palmerston North, New Zealand, were measured during 2 winters. The data were simulated using a simple analytical transfer function model (TFM). Urea fertiliser applied at the rate of 120 kg N/ha to one paddock was treated as a pulse input to the pool of resident soil NO-3. A source{sink term was included for plant uptake and net mineralisation (including any effect of denitrification). During the first winter (1990), a TFM using either a 1-parameter Burns probability density function (pdf) for solute travel, or a 2-parameter lognormal pdf, satisfactorily simulated the NO-3 concentration trends and predicted the total amounts of N leached. The pdf parameters were derived from previous chloride leaching data for this site. The best-fit value for the transport volume θst, the key parameter in the Burns pdf, was set at 0·37 m3 /m3 in 1990, as used in previous modelling of sulfate leaching. However, a value of 0 ·25 m3 /m3 in the Burns pdf gave better simulations of the 1991 data. This was probably due to more intense rain events during the early part of the drainage season in 1991 compared with 1990, which resulted in more preferential flow through the soil and a lower value for θst. The simulations for both years showed that ≥50% of the total leachable NO-3 was retained in the soil, despite normal winter drainage of about 300 mm. Ideally, the appropriate value of st should be determined by independent measurement. It may need to be adjusted according to the likely incidence of preferential flow early in the winter when NO-3 concentrations are highest. Provided the average initial soil NO-3 concentration can be estimated and a net source{sink term defined, the amount of NO-3 leached in drained soils can be satisfactorily modelled using the TFM approach with a 1-parameter pdf. Duplex soils which have a fluctuating watertable in the A horizon over an impermeable B horizon may prove to be an analogous system.

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