New Zealand's intensively grazed pastures receive the majority of nitrogen (N) input in the form of urea, which is the major constituent of animal urine and the most common form of mineral N in ...inorganic N fertilizers. In soil, urea is rapidly hydrolyzed to ammonium (NH4+) ions, a part of which may be lost as ammonia (NH3) and subsequently as nitrous oxide (N2O), which is a greenhouse gas. Two glasshouse experiments were conducted to study the effect of a urease inhibitor (UI), N-(n-butyl) thiophosphoric triamide (NBPT), commercially named Agrotain, applied with urine and urea on urea hydrolysis and NH3 and N2O emissions. Treatments included the commercially available products Sustain Yellow (urea+Agrotain+4% sulfur coating), Sustain Green (urea+Agrotain) and urea, and cattle urine (476kgNha−1) with and without Agrotain applied to intact soil cores of a fine sandy loam soil. The addition of Agrotain to urine and urea (i.e. Sustain Green) reduced NH3 emission by 22% to 47%, respectively. Agrotain was also effective in reducing N2O emissions from urine and Sustain Green by 62% and 48%, respectively. The reduction in N2O emissions varied with the type and amount of N applied and plant N uptake. Plant N uptake was significantly higher in the soil cores receiving Agrotain with urea than urea alone, but the slight increase in dry matter yield was non-significant. Hence, urease inhibitor reduced N losses through NH3 and N2O emissions, thereby increasing plant uptake of N.
Urease inhibitor reduces ammonia volatilization and nitrous oxide emission by decreasing both ammonium and nitrate concentrations in soil and hence increase plant N uptake. Display omitted
► Quantify the reduction of N lost as NH3 and N2O from urea and urine with urease inhibitor application ► Comparison of three different commercially available urea products (with UI and sulfur coating) ► Urease inhibitor significantly reduced NH3 emissions from both urea and urine with variable effect on N2O emissions. ► Application of UI also tends to increase N uptake by plants when applied with urea.
Nitrogen (N) losses via nitrate (NO
3
−) leaching, ammonia (NH
3) volatilization and nitrous oxide (N
2O) emissions from grazed pastures in New Zealand are one of the major contributors to ...environmental degradation. The use of N inhibitors (urease and nitrification inhibitors) may have a role in mitigating these N losses. A one-year field experiment was conducted on a permanent dairy-grazed pasture site at Massey University, Palmerston North, New Zealand to quantify these N losses and to assess the effect of N inhibitors in reducing such losses during May 2005–2006. Cow urine at 600 kg N ha
−1 rate with or without urease inhibitor N-(n-butyl) thiophosphoric triamide (nBTPT) or (trade name “Agrotain”) (3 L ha
−1), nitrification inhibitor dicyandiamide (DCD) (7 kg ha
−1) and the use of double inhibitor (DI) containing a combination of both Agrotain and DCD (3:7) were applied to field plots in autumn, spring and summer. Pasture production, NH
3 and N
2O fluxes, soil mineral N concentrations, microbial biomass C and N, and soil pH were measured following the application of treatments during each season. All measured parameters, except soil microbial biomass C and N, were influenced by the added inhibitors during the three seasons. Agrotain reduced NH
3 emissions over urine alone by 29%, 93% and 31% in autumn, spring and summer respectively but had little effect on N
2O emission. DCD reduced N
2O emission over urine alone by 52%, 39% and 16% in autumn, spring and summer respectively but increased NH
3 emission by 56%, 9% and 17% over urine alone during those three seasons. The double inhibitor reduced NH
3 by 14%, 78% and 9% and N
2O emissions by 37%, 67% and 28% over urine alone in autumn, spring and summer respectively. The double inhibitor also increased pasture dry matter by 10%, 11% and 8% and N uptake by the 17%, 28% and 10% over urine alone during autumn, spring and summer respectively. Changes in soil mineral N and pH suggested a delay in urine-N hydrolysis with Agrotain, and reduced nitrification with DCD. The combination of Agrotain and DCD was more effective in reducing both NH
3 and N
2O emissions, improving pasture production, controlling urea hydrolysis and retaining N in NH
4
+ form. These results suggest that the combination of both urease and nitrification inhibitors may have the most potential to reduce N losses if losses are associated with urine and improve pasture production in intensively grazed systems.
Globally, animal excreta (dung and urine) deposition onto grazed pastures represents more than half of anthropogenic nitrous oxide (N2O) emissions. To account for these emissions, New Zealand ...currently employs urine and dung emission factor (EF3) values of 1.0% and 0.25%, respectively, for all livestock. These values are primarily based on field studies conducted on fertile, flatland pastures predominantly used for dairy cattle production but do not consider emissions from hill land pastures primarily used for sheep, deer and non-dairy cattle.
The objective of this study was to determine the most suitable urine and dung EF3 values for dairy cattle, non-dairy cattle, and sheep grazing pastures on different slopes based on a meta-analysis of New Zealand EF3 studies. As none of the studies included deer excreta, deer EF3 values were estimated from cattle and sheep values. The analysis revealed that a single dung EF3 value should be maintained, although the value should be reduced from 0.25% to 0.12%. Furthermore, urine EF3 should be disaggregated by livestock type (cattle > sheep) and topography (flatland and low sloping hill country > medium and steep sloping hill country), with EF3 values ranging from 0.08% (sheep urine on medium and steep slopes) to 0.98% (dairy cattle on flatland and low slopes). While the mechanism(s) causing differences in urine EF3 values for sheep and cattle are unknown, the ‘slope effect’ on urine EF3 is partly due to differences in soil chemical and physical characteristics, which influence soil microbial processes on the different slope classes.
The revised EF3 values were used in an updated New Zealand inventory approach, resulting in 30% lower national N2O emissions for 2017 compared to using the current EF3 values. We recommend using the revised EF3 values in New Zealand's national greenhouse gas inventory to more accurately capture N2O emissions from livestock grazing.
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•Current NZ-specific N2O emission factors (EF3) are 1.0% (urine) and 0.25% (dung).•A meta-analysis of 1217 EF3 data representative of livestock grazing was completed.•The analysis showed that the dung EF3 values should be reduced to 0.12%.•Urine EF3 values ranged from 0.08% to 0.98%, based on livestock type and topography.•We recommend the revised values are employed in NZ's national N2O inventory.
Nitrous oxide (N
2O) emissions from grazed pastures represent a significant source of atmospheric N
2O. With an improved understanding and quantification of N sources, transformation processes, and ...soil and climatic conditions controlling N
2O emissions, a number of management options can be identified to reduce N
2O emissions from grazed pasture systems. The mitigation options discussed in this paper are: optimum soil management, limiting the amount of N fertiliser or effluent applied when soil is wet; lowering the amount of N excreted in animal urine by using low-N feed supplements as an alternative to fertiliser N-boosted grass; plant and animal selection for increased N use efficiency, using N process inhibitors that inhibit the conversion of urea to ammonium and ammonium to nitrate in soil; use of stand-off/feed pads or housing systems during high risk periods of N loss. The use of single or multiple mitigation options always needs to be evaluated in a whole farm system context and account for total greenhouse gas emissions including methane and carbon dioxide. They should focus on ensuring overall efficiency gains through decreasing N losses per unit of animal production and achieving a tighter N cycle. Whole-system life-cycle-based environmental analysis should also be conducted to assess overall environmental emissions associated the N
2O mitigation options.
We quantified nitrous oxide emission factors (N
2
O EFs) for cattle urine patches established using two simulation methods: (1) a uniformly wetted area (UWA) and (2) a naturally expanding effective ...area (NEEA). Field experiments were conducted on long-term grasslands in New Zealand (NZ1 and NZ2) and Ireland (IRE) for varying urine nitrogen (N) application rates in two initial soil moisture regimes (below field capacity and field capacity). Nitrous oxide emissions were measured using static chambers for a period of 120, 133 and 85 days at NZ1, NZ2 and IRE, respectively. Nitrous oxide EFs were unaffected by patch type (UWA = 0.99%; NEEA = 1.07%) across varying urine N application rates in NZ1 whereas in NZ2, EFs varied with urine N application rate only for the NEEA patches in below field capacity soils (
P
< 0.05). In IRE, we observed a ~ fourfold difference in the mean N
2
O EF between the UWA (0.67 ± 0.24%) and NEEA (0.18 ± 0.04%) patches in below field capacity soils (
P
< 0.05) but no significant differences in EFs were detected between the UWA (0.75 ± 0.14%) and NEEA (0.53 ± 0.08%) patches at field capacity soils. Our study suggests that patch simulation method and initial soil water content can independently affect N
2
O EFs in urine-affected pasture but factor effects may be largely site and/or soil specific.
•Urea fertiliser EF1 varied from 0.03% to 1.52% of N applied.•Farm dairy effluent (FDE) EF1 ranged from 0.06% to 0.94% of N applied.•Adding DCD or nBTPT to urea fertiliser had little or no effect on ...N2O EF1.•Adding DCD to FDE also had little or no effect on N2O EF1.•Historical application of FDE to pasture had no effect on FDE EF1.
There is currently a limited number of New Zealand studies quantifying nitrous oxide (N2O) emission factors (EF1, N2O emissions as a percentage of N applied) for farm dairy effluent (FDE) and urea fertiliser. Therefore, two experiments were conducted in four regions of New Zealand to determine EF1 for FDE and urea fertiliser applied to pastures with contrasting soils and climatic conditions. Experiment 1 included urease and nitrification inhibitors to determine their effect on EF1. Urea treatments included (i) standard urea; (ii) urea amended with the nitrification inhibitor dicyandiamide (DCD) at 0.02kgDCDkg−1 nitrogen (N) and (iii) urea amended with the urease inhibitor N-(n-butyl) thiophosphoric triamide (nBTPT) at 250mgnBTPTkg−1urea, while FDE was applied with or without DCD, at 10kgDCDha−1. Experiment 2 focused solely on FDE, which was applied to pastures that had either never received FDE or had a history of repeated application of FDE over several years. Urea fertiliser produced a large variation in EF1 values, ranging from 0.03% to 1.52%. Application of FDE resulted in EF1 ranging from 0.06% to 0.94% across both experiments. The urease and nitrification inhibitors had little or no effect on reducing EF1 from urea fertiliser and FDE application. The history of repeated applications of FDE to pasture also had no effect on EF1.
The objective of this work was to study the degradation kinetics of a nitrification inhibitor (NI), dicyandiamide (DCD), and evaluate its effectiveness in reducing nitrous oxide (N₂O) emissions in ...different types of soils. Three soils contrasting in texture, mineralogy, and organic carbon (C) content were incubated alone (control) or with urine at 600mg N/kg soil with 3 levels of DCD (0, 10, and 20mg/kg). Emissions of N₂O and carbon dioxide (CO₂) were measured during the 58-day incubation. Simultaneously, subsamples were collected periodically from the incubating soils (40-day incubation) and the amounts of DCD, NH₄⁺, and NO₃⁻ were determined. Our results showed that the half-life of DCD in these laboratory incubating soils at 25°C was 6-15 days and was longer at the higher rate of DCD application. Of the 3 soils studied, DCD degradation was fastest in the brown loam allophanic soil (Typic orthic allophanic) and slowest in the silt loam non-allophanic soil (Argillic-fragic Perch-gley Pallic). The differences in DCD degradation among these soils can be attributed to the differences in the adsorption of DCD and in the microbial activities of the soils. Among the 3 soils the highest reduction in N₂O emissions with DCD from the urine application was measured in the non-allophanic silt loam soil followed by non-allophanic sandy loam soil and allophanic brown loam soil. There was no adverse impact of DCD application on soil respiratory activity or microbial biomass.
•Electro-mechanical response of the Pneumatically Coupled Dielectric Elastomer (PCDE) based actuators was investigated.•High voltage performances of PCDE actuators up to 3kV in the frequency range of ...0 to 2 kHz were studied.•Harmonics and super harmonic modes were characterized for the time using indigenously developed magnetoresistive field sensor.•The phase shift of 180 degree at resonance was observed for PCDE actuators.•The actuator have potential applications in Micro aerial Vehicle.
Pneumatically Coupled Dielectric Elastomer (PCDE) based actuators with air as an intervening medium, were developed. Fabrication of these actuators have been carried out using dielectric elastomer membrane on both sides of an insulating annular holder of diameter 10 mm. The membrane at the bottom side acts as an active membrane which consists of ultrathin metal electrode on it’s both sides, whereas top membrane acts as a passive membrane. Mechanical performance of PCDE actuators were studied using bulge test method. Initially, high voltage performance of both active and passive membranes with electric field strength upto 40 MV/m were characterized by sweeping the frequency from 0 to 2 kHz and their frequencies responses were analyzed. With fixing a cylindrical magnet as a load at the center of the passive membrane, further experimental studies on several harmonics along with their phase shift were performed using an indigenously developed magnetoresistive sensor and the detailed analysis on these observations are presented.
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