scholarly journals The acetylene inhibition technique to determine total denitrification (N<sub>2</sub> + N<sub>2</sub>O) losses from soil samples: potentials and limitations

2012 ◽  
Vol 9 (3) ◽  
pp. 2851-2882 ◽  
Author(s):  
R. Felber ◽  
F. Conen ◽  
C. R. Flechard ◽  
A. Neftel
Keyword(s):  
Precise Determination ◽  
High Temporal Resolution ◽  
Laboratory System ◽  
Soil Cores ◽  
N Budget ◽  
Central Switzerland ◽  
Intensively Managed ◽  
Intact Soil Cores ◽  
Denitrification Loss ◽  
Inhibition Technique

Abstract. The loss of N2 from intensively managed agro-ecosystems is an important part of the N budget. The monitoring of N2 emissions at the field scale is impossible due to the high atmospheric background of 78%, which precludes the measurement of fluxes. The acetylene (C2H2) inhibition technique is a rather simple, albeit imperfect, method to determine N2 losses from entire soil cores. Despites serious limitations it is one among very few methodological options to estimate total denitrification at high temporal resolution and on small spatial scale, with limited workload and costs involved. A laboratory system with two different detection systems (photoacoustic IR spectroscopy and gas chromatography) is presented, which allowed parallel measurements of up to 7 intact soil cores in air-tight glass tubes in a temperature controlled cabinet (adjusted to field conditions) with an automated C2H2 injection. A survey of total denitrification losses (N2 + N2O) over 1.5 yr in soil from an intensively managed, cut grassland system in central Switzerland showed a lower bound loss in the range of 6 to 25 kg N ha−1 yr−1 (3–13% of added N), roughly 3.4 times higher than the N2O loss. However, several drawbacks of the C2H2 inhibition technique preclude a more precise determination of the total denitrification loss.

scholarly journals Theoretical and practical limitations of the acetylene inhibition technique to determine total denitrification losses

2012 ◽  
Vol 9 (10) ◽  
pp. 4125-4138 ◽  
Author(s):  
R. Felber ◽  
F. Conen ◽  
C. R. Flechard ◽  
A. Neftel
Keyword(s):  
Spatial Scales ◽  
Eddy Correlation ◽  
High Temporal Resolution ◽  
Laboratory System ◽  
Soil Cores ◽  
N Budget ◽  
Intensively Managed ◽  
Intact Soil Cores ◽  
Inhibition Technique ◽  
Intact Soil

Abstract. The loss of N2 from intensively managed agro-ecosystems is an important part of the N budget. Flux monitoring of N2 emissions at the field scale, e.g., by eddy correlation or aerodynamic gradient method, is impossible due to the large atmospheric N2 background (78%). The acetylene (C2H2) inhibition technique (AIT) is a rather simple and frequently used, albeit imperfect, method to determine N2 losses from intact soil cores. In principle, AIT allows an estimation of total denitrification at high temporal resolution and on small spatial scales, with limited workload and costs involved. To investigate its potential and limitations, a laboratory system with two different detection systems (photoacoustic IR spectroscopy and gas chromatography) is presented, which allowed simultaneous measurements of up to 7 intact soil cores in air-tight glass tubes in a temperature controlled cabinet (adjusted to field conditions) with automated C2H2 injection. A survey of total denitrification losses (N2 + N2O) over 1.5 yr in soil cores from an intensively managed, cut grassland system in central Switzerland supports previous reports on severe limitations of the AIT, which precluded reliable estimates of total denitrification losses. Further, the unavoidable sampling and transfer of soil samples to the laboratory causes unpredictable deviations from the denitrification activity in the field.

scholarly journals Denitrification Rate and Its Potential to Predict Biogenic N2O Field Emissions in a Mediterranean Maize-Cropped Soil in Southern Italy

Land ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 97 ◽  
Author(s):  
Annachiara Forte ◽  
Angelo Fierro
Keyword(s):  
Pore Space ◽  
Denitrification Rate ◽  
Linear Functions ◽  
N2o Emissions ◽  
Soil Cores ◽  
High Soil ◽  
N2o Fluxes ◽  
Intact Soil Cores ◽  
Intact Soil ◽  
Soil Nitrates

The denitrification rate in C2H2-amended intact soil cores and soil N2O fluxes in closed static chambers were monitored in a Mediterranean irrigated maize-cropped field. The measurements were carried out during: (i) a standard fertilization management (SFM) activity and (ii) a manipulation experimental (ME) test on the effects of increased and reduced application rates of urea at the late fertilization. In the course of the SFM, the irrigations following early and late nitrogen fertilization led to pulses of denitrification rates (up to 1300 μg N2O-N m−2 h−1) and N2O fluxes (up to 320 μg N2O-N m−2 h−1), thanks to the combined action of high soil temperatures and not limiting nitrates and water filled pore space (WFPS). During the ME, high soil nitrates were noted in all the treatments in the first one month after the late fertilization, which promoted marked N-losses by microbial denitrification (from 500 to 1800 μg N2O-N m−2 h−1) every time the soil WFPS was not limiting. At similar maize yield responses to fertilizer treatments, this result suggested no competition for N between plant roots and soil microbial community and indicated a probable surplus of nitrogen fertilizer input at the investigated farm. Correlation and regression analyses (CRA) on the whole set of data showed significant relations between both the denitrification rates and the N2O fluxes with three soil physical-chemical parameters: nitrate concentration, WFPS and temperature. Specifically, the response functions of denitrification rate to soil nitrates, WFPS and temperature could be satisfactorily modelled according to simple Michaelis-Menten kinetic, exponential and linear functions, respectively. Furthermore, the CRA demonstrated a significant exponential relationship between N2O fluxes and denitrification and simple empirical functions to predict N2O emissions from the denitrification rate appeared more fitting (higher concordance correlation coefficient) than the predictive empirical algorithm based on soil nitrates, WFPS and temperature. In this regard, the empirically established relationships between the denitrification rate on intact soil cores under field conditions and the soil variables provided local-specific threshold values and coefficients which may effectively work to calibrate and adapt existing N2O process-based simulation models to the local pedo-climatic conditions.

Effects of Starch Encapsulation on Clomazone and Atrazine Movement in Soil and Clomazone Volatilization

Weed Science ◽  
1995 ◽  
Vol 43 (3) ◽  
pp. 445-453 ◽  
Author(s):  
Todd L. Mervosh ◽  
Edward W. Stoller ◽  
F. William Simmons ◽  
Timothy R. Ellsworth ◽  
Gerald K. Sims
Keyword(s):  
Unsaturated Flow ◽  
Soil Surface ◽  
Silty Clay ◽  
Silt Loam ◽  
Starch Granules ◽  
Soil Cores ◽  
Silty Clay Loam ◽  
Intact Soil Cores ◽  
Water Tension ◽  
Intact Soil

The effects of formulation on clomazone volatilization and transport through soil were studied. After 22 days of leaching under unsaturated flow in 49-cm long intact soil cores, greater clomazone movement was observed in Plainfield sand than in Cisne silt loam or Drummer silty clay loam soils. Soil clomazone concentrations resulting in injury to oats occurred throughout Plainfield soil cores but were restricted to the upper 14 cm of Cisne and Drummer soils. In addition, clomazone was detected in the leachate from Plainfield soil only. In a similar study with Plainfield sand cores, clomazone was less mobile than atrazine; encapsulation of the herbicides in starch granules did not affect clomazone movement but greatly decreased atrazine movement from the soil surface. Similarly, starch encapsulation did not affect bioavailability of clomazone but did reduce bioavailability of atrazine. In a laboratory study with continual air flow, volatilization of clomazone applied to the soil surface was reduced by encapsulation in starch and starch/clay granules. Clomazone volatilization was not affected by soil water content within a range of 33 to 1500 kPa water tension. Following soil saturation with water, clomazone volatilization from both liquid and granular formulations increased. Granule size appeared to have a greater impact than granule composition on clomazone volatilization.

scholarly journals Leaching of Cryptosporidium parvum Oocysts, Escherichia coli, and a Salmonella enterica Serovar Typhimurium Bacteriophage through Intact Soil Cores following Surface Application and Injection of Slurry

2011 ◽  
Vol 77 (22) ◽  
pp. 8129-8138 ◽  
Author(s):  
Anita Forslund ◽  
Bo Markussen ◽  
Lise Toenner-Klank ◽  
Tina B. Bech ◽  
Ole Stig Jacobsen ◽  
...  
Keyword(s):  
Cryptosporidium Parvum ◽  
Pore Volume ◽  
Relative Concentration ◽  
Weather Conditions ◽  
Soil Cores ◽  
Content Type ◽  
E Coli ◽  
Serovar Typhimurium ◽  
Intact Soil Cores ◽  
Intact Soil

ABSTRACTIncreasing amounts of livestock manure are being applied to agricultural soil, but it is unknown to what extent this may be associated with contamination of aquatic recipients and groundwater if microorganisms are transported through the soil under natural weather conditions. The objective of this study was therefore to evaluate how injection and surface application of pig slurry on intact sandy clay loam soil cores influenced the leaching ofSalmonella entericaserovar Typhimurium bacteriophage 28B,Escherichia coli, andCryptosporidium parvumoocysts. All three microbial tracers were detected in the leachate on day 1, and the highest relative concentration was detected on the fourth day (0.1 pore volume). Although the concentration of the phage 28B declined over time, the phage was still found in leachate at day 148.C. parvumoocysts and chloride had an additional rise in the relative concentration at a 0.5 pore volume, corresponding to the exchange of the total pore volume. The leaching ofE. coliwas delayed compared with that of the added microbial tracers, indicating a stronger attachment to slurry particles, butE. colicould be detected up to 3 months. Significantly enhanced leaching of phage 28B and oocysts by the injection method was seen, whereas leaching of the indigenousE. coliwas not affected by the application method. Preferential flow was the primary transport vehicle, and the diameter of the fractures in the intact soil cores facilitated transport of all sizes of microbial tracers under natural weather conditions.

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