Mitigation of N2O emissions from surface-irrigated cropping systems using water management and the nitrification inhibitor DMPP

Soils under irrigated agriculture are a significant source of nitrous oxide (N2O) owing to high inputs of nitrogen (N) fertiliser and water. This study investigated the potential for N2O mitigation by manipulating the soil moisture deficit through irrigation scheduling in combination with, and in comparison to, using the nitrification inhibitor, 3,4-dimethylpyrazole phosphate (DMPP). Lysimeter cores planted with wheat were fitted with automated chambers for continuous measurements of N2O fluxes. Treatments included conventional irrigation (CONV), reduced deficit irrigation (RED), CONV-DMPP and RED-DMPP. The total seasonal volume of irrigation water applied was constant for all treatments but the timing and quantity in individual irrigation applications varied among treatments. 15N-labelled urea was used to track the source of N2O emissions and plant N uptake. The majority of N2O emissions occurred immediately after irrigations began on 1 September 2014. Applying RED and DMPP individually slightly decreased N2O emissions but when applied in combination (RED-DMPP) the greatest reductions in N2O emissions were observed. There was no effect of treatments on plant N uptake, 15N recovery or yield possibly because the system was not N limited. Half of the plant N and 53% to 87% of N2O was derived from non-fertiliser sources in soil, highlighting the opportunity to further exploit this valuable N pool.

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Sources of nitrous oxide from 15N-labelled animal urine and urea fertiliser with and without a nitrification inhibitor, dicyandiamide (DCD)

Soil Research ◽

10.1071/sr07093 ◽

2008 ◽

Vol 46 (1) ◽

pp. 76 ◽

Cited By ~ 41

Author(s):

H. J. Di ◽

K. C. Cameron

Keyword(s):

Nitrous Oxide ◽

Dairy Cow ◽

Priming Effect ◽

Nitrification Inhibitor ◽

Major Effect ◽

N2o Emissions ◽

Soil N ◽

Cow Urine ◽

Nitrification And Denitrification ◽

N Pool

A field lysimeter study was conducted to determine the sources of N2O emitted following the application of dairy cow urine and urea fertiliser labelled with 15N, with and without a nitrification inhibitor, dicyandiamide (DCD). The results show that the application of cow urine at 1000 kg N/ha significantly increased N2O emissions above that from urea applied alone at 25 kg N/ha. The application of urine seemed to have a priming effect, increasing N2O emissions from the soil N pool. Treating the soil with DCD significantly (P < 0.05) decreased N2O emissions from the urine-applied treatment by 72%. The percentage of N2O-N derived from the applied N was 53.1% in the urine-applied treatment and this was reduced to 29.9% when DCD was applied. On average, about 43% of the N2O emitted in the urine-applied treatments was from nitrification. The application of DCD did not have a major effect on the relative contributions of nitrification and denitrification to N2O emissions in the urine treatments. This indicates that the DCD nitrification inhibitor decreased the contributions to N2O emissions from both nitrification and denitrification.

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Greenhouse gas (N2O and CH4) fluxes under nitrogen-fertilised dryland wheat and barley on subtropical Vertosols: risk, rainfall and alternatives

Soil Research ◽

10.1071/sr15338 ◽

2016 ◽

Vol 54 (5) ◽

pp. 634 ◽

Cited By ~ 13

Author(s):

Graeme D. Schwenke ◽

David F. Herridge ◽

Clemens Scheer ◽

David W. Rowlings ◽

Bruce M. Haigh ◽

...

Keyword(s):

N Uptake ◽

Nitrification Inhibitor ◽

N2o Emission ◽

N2o Emissions ◽

Soil Mineral N ◽

Soil Mineral ◽

Mineral N ◽

Before And After ◽

Ch4 Uptake ◽

Crop N Uptake

The northern Australian grains industry relies on nitrogen (N) fertiliser to optimise yield and protein, but N fertiliser can increase soil fluxes of nitrous oxide (N2O) and methane (CH4). We measured soil N2O and CH4 fluxes associated with wheat (Triticum aestivum) and barley (Hordeum vulgare) using automated (Expts 1, 3) and manual chambers (Expts 2, 4, 5). Experiments were conducted on subtropical Vertosol soils fertilised with N rates of 0–160kgNha–1. In Expt 1 (2010), intense rainfall for a month before and after sowing elevated N2O emissions from N-fertilised (80kgNha–1) wheat, with 417gN2O-Nha–1 emitted compared with 80g N2O-Nha–1 for non-fertilised wheat. Once crop N uptake reduced soil mineral N, there was no further treatment difference in N2O. Expt 2 (2010) showed similar results, however, the reduced sampling frequency using manual chambers gave a lower cumulative N2O. By contrast, very low rainfall before and for several months after sowing Expt 3 (2011) resulted in no difference in N2O emissions between N-fertilised and non-fertilised barley. N2O emission factors were 0.42, 0.20 and –0.02 for Expts 1, 2 and 3, respectively. In Expts 4 and 5 (2011), N2O emissions increased with increasing rate of N fertiliser. Emissions were reduced by 45% when the N fertiliser was applied in a 50:50 split between sowing and mid-tillering, or by 70% when urea was applied with the nitrification inhibitor 3,4-dimethylpyrazole-phosphate. Methane fluxes were typically small and mostly negative in all experiments, especially in dry soils. Cumulative CH4 uptake ranged from 242 to 435g CH4-Cha–1year–1, with no effect of N fertiliser treatment. Considered in terms of CO2 equivalents, soil CH4 uptake offset 8–56% of soil N2O emissions, with larger offsets occurring in non-N-fertilised soils. The first few months from N fertiliser application to the period of rapid crop N uptake pose the main risk for N2O losses from rainfed cereal cropping on subtropical Vertosols, but the realisation of this risk is dependent on rainfall. Strategies that reduce the soil mineral N pool during this time can reduce the risk of N2O loss.

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Comparison of grain yields and N2O emissions on Oxisol and Vertisol soils in response to fertiliser N applied as urea or urea coated with the nitrification inhibitor 3,4-dimethylpyrazole phosphate

Soil Research ◽

10.1071/sr15336 ◽

2016 ◽

Vol 54 (5) ◽

pp. 552 ◽

Cited By ~ 16

Author(s):

Massimiliano De Antoni Migliorati ◽

Mike Bell ◽

David Lester ◽

David W. Rowlings ◽

Clemens Scheer ◽

...

Keyword(s):

Grain Yield ◽

Crop Yields ◽

Cropping Systems ◽

Nitrification Inhibitor ◽

Measuring System ◽

Yield Response ◽

N2o Emissions ◽

North East ◽

Fertiliser Application ◽

N Rates

The potential for elevated nitrous oxide (N2O) losses is high in subtropical cereal cropping systems in north-east Australia, where the fertiliser nitrogen (N) input is one single application at or before planting. The use of urea coated with the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) has been reported to substantially decrease N2O emissions and increase crop yields in humid, high-intensity rainfall environments. However, it is still uncertain whether this product is similarly effective in contrasting soil types in the cropping region of north-east Australia. In this study the grain yield response of sorghum (Sorghum bicolor L. Moench) to rates of fertiliser N applied as urea or urea coated with DMPP were compared in crops grown on a Vertisol and an Oxisol in southern Queensland. Seasonal N2O emissions were monitored on selected treatments for the duration of the cropping season and the early stages of a subsequent fallow period using a fully automated high-frequency greenhouse gas measuring system. On each soil the tested treatments included an unfertilised control (0kgNha–1) and two fertilised treatments chosen on the basis of delivering at least 90% of seasonal potential grain yield (160 and 120kgNha–1 on the Vertisol and Oxisol respectively) or at a common (suboptimal) rate at each site (80kgNha–1). During this study DMPP had a similar impact at both sites, clearly inhibiting nitrification for up to 8 weeks after fertiliser application. Despite the relatively dry seasonal conditions during most of the monitoring period, DMPP was effective in abating N2O emissions on both soils and on average reduced seasonal N2O emissions by 60% compared with conventional urea at fertiliser N rates equivalent to those producing 90% of site maximum grain yield. The significant abatement of N2O emissions observed with DMPP, however, did not translate into significant yield gains or improvements in agronomic efficiencies of fertiliser N use. These results may be due to the relatively dry growing season conditions before the bulk of crop N acquisition, which limited the exposure of fertiliser N to large losses due to leaching and denitrification.

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Biochar addition indirectly affects N2O emissions via soil moisture and plant N uptake

Soil Biology and Biochemistry ◽

10.1016/j.soilbio.2012.10.035 ◽

2013 ◽

Vol 58 ◽

pp. 99-106 ◽

Cited By ~ 122

Author(s):

S. Saarnio ◽

K. Heimonen ◽

R. Kettunen

Keyword(s):

Soil Moisture ◽

N Uptake ◽

N2o Emissions ◽

Plant N Uptake

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Effect of enhanced efficiency fertilisers on nitrous oxide emissions in a sub-tropical cereal cropping system

Soil Research ◽

10.1071/sr15332 ◽

2016 ◽

Vol 54 (5) ◽

pp. 544 ◽

Cited By ~ 22

Author(s):

Clemens Scheer ◽

David W. Rowlings ◽

Massimiliano De Antoni Migliorati ◽

David W. Lester ◽

Mike J. Bell ◽

...

Keyword(s):

Nitrous Oxide ◽

Crop Yields ◽

Cropping Systems ◽

Nitrification Inhibitor ◽

Cropping System ◽

Measuring System ◽

Nitrous Oxide Emissions ◽

N2o Emissions ◽

N Fertilisers ◽

Polymer Coated Urea

To meet the global food demand in the coming decades, crop yields per unit area must increase. This can only be achieved by a further intensification of existing cropping systems and will require even higher inputs of N fertilisers, which may result in increased losses of nitrous oxide (N2O) from cropped soils. Enhanced efficiency fertilisers (EEFs) have been promoted as a potential strategy to mitigate N2O emissions and improve nitrogen use efficiency (NUE) in cereal cropping systems. However, only limited data are currently available on the use of different EEF products in sub-tropical cereal systems. A field experiment was conducted to investigate the effect of three different EEFs on N2O emissions, NUE and yield in a sub-tropical summer cereal cropping system in Australia. Over an entire year soil N2O fluxes were monitored continuously (3h sampling frequency) with a fully-automated measuring system. The experimental site was fertilised with different nitrogen (N) fertilisers applied at 170kgNha–1, namely conventional urea (Urea), urea with the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP), polymer-coated urea (PCU), and urea with the nitrification inhibitor nitrapyrin (Nitrapyrin). Nitrous oxide emissions were highly episodic and mainly controlled by heavy rainfall events within two months of planting and fertiliser N application. Annual N2O emissions in the four treatments amounted to 2.31, 0.40, 0.69 and 1.58kgN2O-Nha–1year–1 for Urea, DMPP, PCU and Nitrapyrin treatments, respectively, while unfertilised plots produced an average of 0.16kgN2O-Nha–1year–1. Two of the tested products (DMPP and PCU) were found to be highly effective, decreasing annual N2O losses by 83% and 70%, respectively, but did not affect yield or NUE. This study shows that EEFs have a high potential to decrease N2O emissions from sub-tropical cereal cropping systems. More research is needed to assess if the increased costs of EEFs can be compensated by lower fertiliser application rates and/or yield increases.

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The Nitrification Inhibitor Vizura® Reduces N2O Emissions When Added to Digestate before Injection under Irrigated Maize in the Po Valley (Northern Italy)

Agronomy ◽

10.3390/agronomy9080431 ◽

2019 ◽

Vol 9 (8) ◽

pp. 431 ◽

Cited By ~ 3

Author(s):

Marcello Ermido Chiodini ◽

Alessia Perego ◽

Marco Carozzi ◽

Marco Acutis

Keyword(s):

Soil Depth ◽

Cropping Systems ◽

Pore Space ◽

Block Design ◽

Nitrification Inhibitor ◽

N Fertilization ◽

N2o Emissions ◽

Air Samples ◽

Po Valley ◽

Randomized Block Design

The agricultural area in the Po Valley is prone to high nitrous oxide (N2O) emissions as it is characterized by irrigated maize-based cropping systems, high amounts of nitrogen supplied, and elevated air temperature in summer. Here, two monitoring campaigns were carried out in maize fertilized with raw digestate in a randomized block design in 2016 and 2017 to test the effectiveness of the 3, 4 DMPP inhibitor Vizura® on reducing N2O-N emissions. Digestate was injected into 0.15 m soil depth at side-dressing (2016) and before sowing (2017). Non-steady state chambers were used to collect N2O-N air samples under zero N fertilization (N0), digestate (D), and digestate + Vizura® (V). Overall, emissions were significantly higher in the D treatment than in the V treatment in both 2016 and 2017. The emission factor (EF, %) of V was two and four times lower than the EF in D in 2016 and 2017, respectively. Peaks of NO3-N generally resulted in N2O-N emissions peaks, especially during rainfall or irrigation events. The water-filled pore space (WFPS, %) did not differ between treatments and was generally below 60%, suggesting that N2O-N emissions were mainly due to nitrification rather than denitrification.

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Performance Assessment of Five Different Soil Moisture Sensors under Irrigated Field Conditions in Oklahoma

Sensors ◽

10.3390/s18113786 ◽

2018 ◽

Vol 18 (11) ◽

pp. 3786 ◽

Cited By ~ 9

Author(s):

Sumon Datta ◽

Saleh Taghvaeian ◽

Tyson Ochsner ◽

Daniel Moriasi ◽

Prasanna Gowda ◽

...

Keyword(s):

Soil Moisture ◽

Cropping Systems ◽

Irrigation Management ◽

Clay Content ◽

Field Capacity ◽

Irrigation Scheduling ◽

Irrigated Agriculture ◽

Undisturbed Soil ◽

Soil Moisture Sensors ◽

Rosetta Model

Meeting the ever-increasing global food, feed, and fiber demands while conserving the quantity and quality of limited agricultural water resources and maintaining the sustainability of irrigated agriculture requires optimizing irrigation management using advanced technologies such as soil moisture sensors. In this study, the performance of five different soil moisture sensors was evaluated for their accuracy in two irrigated cropping systems, one each in central and southwest Oklahoma, with variable levels of soil salinity and clay content. With factory calibrations, three of the sensors had sufficient accuracies at the site with lower levels of salinity and clay, while none of them performed satisfactorily at the site with higher levels of salinity and clay. The study also investigated the performance of different approaches (laboratory, sensor-based, and the Rosetta model) to determine soil moisture thresholds required for irrigation scheduling, i.e., field capacity (FC) and wilting point (WP). The estimated FC and WP by the Rosetta model were closest to the laboratory-measured data using undisturbed soil cores, regardless of the type and number of input parameters used in the Rosetta model. The sensor-based method of ranking the readings resulted in overestimation of FC and WP. Finally, soil moisture depletion, a critical parameter in effective irrigation scheduling, was calculated by combining sensor readings and FC estimates. Ranking-based FC resulted in overestimation of soil moisture depletion, even for accurate sensors at the site with lower levels of salinity and clay.

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Root-Derived Proteases as a Plant Tool to Access Soil Organic Nitrogen; Current Stage of Knowledge and Controversies

Plants ◽

10.3390/plants10040731 ◽

2021 ◽

Vol 10 (4) ◽

pp. 731

Author(s):

Bartosz Adamczyk

Keyword(s):

Cropping Systems ◽

N Uptake ◽

Organic N ◽

Inorganic N ◽

Available N ◽

Plant Nitrogen ◽

N Cycle ◽

Soil Organic Nitrogen ◽

Use Efficiency ◽

N Pool

Anthropogenic deterioration of the global nitrogen (N) cycle emerges mainly from overuse of inorganic N fertilizers in nutrient-limited cropping systems. To counteract a further dysregulation of the N cycle, we need to improve plant nitrogen use efficiency. This aim may be reached via unravelling all plant mechanisms to access soil N, with special attention to the dominating high-molecular-mass N pool. Traditionally, we believe that inorganic N is the only plant-available N pool, however, more recent studies point to acquisition of organic N compounds, i.e., amino acids, short peptides, and proteins. The least known mechanism of plants to increase the N uptake is a direct increase of soil proteolysis via root-derived proteases. This paper provides a review of the knowledge about root-derived proteases and also controversies behind this phenomenon.

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Biochar and urease inhibitor mitigate NH3 and N2O emissions and improve wheat yield in a urea fertilized alkaline soil

Scientific Reports ◽

10.1038/s41598-021-96771-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Khadim Dawar ◽

Shah Fahad ◽

M. M. R. Jahangir ◽

Iqbal Munir ◽

Syed Sartaj Alam ◽

...

Keyword(s):

Nitrous Oxide ◽

Grain Yield ◽

Block Design ◽

N Uptake ◽

Nitrous Oxide Emissions ◽

N2o Emissions ◽

Urease Inhibitor ◽

Alkaline Soil ◽

Total N ◽

N Assimilation

AbstractIn this study, we explored the role of biochar (BC) and/or urease inhibitor (UI) in mitigating ammonia (NH3) and nitrous oxide (N2O) discharge from urea fertilized wheat cultivated fields in Pakistan (34.01°N, 71.71°E). The experiment included five treatments [control, urea (150 kg N ha−1), BC (10 Mg ha−1), urea + BC and urea + BC + UI (1 L ton−1)], which were all repeated four times and were carried out in a randomized complete block design. Urea supplementation along with BC and BC + UI reduced soil NH3 emissions by 27% and 69%, respectively, compared to sole urea application. Nitrous oxide emissions from urea fertilized plots were also reduced by 24% and 53% applying BC and BC + UI, respectively, compared to urea alone. Application of BC with urea improved the grain yield, shoot biomass, and total N uptake of wheat by 13%, 24%, and 12%, respectively, compared to urea alone. Moreover, UI further promoted biomass and grain yield, and N assimilation in wheat by 38%, 22% and 27%, respectively, over sole urea application. In conclusion, application of BC and/or UI can mitigate NH3 and N2O emissions from urea fertilized soil, improve N use efficiency (NUE) and overall crop productivity.

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Irrigation Scheduling with Soil Gas Diffusivity as a Decision Tool to Mitigate N2O Emissions from a Urine-Affected Pasture

Agriculture ◽

10.3390/agriculture11050443 ◽

2021 ◽

Vol 11 (5) ◽

pp. 443

Author(s):

Camille Rousset ◽

Timothy J. Clough ◽

Peter R. Grace ◽

David W. Rowlings ◽

Clemens Scheer

Keyword(s):

Irrigation Management ◽

Irrigation Treatment ◽

Irrigation Scheduling ◽

Soil Gas ◽

N2o Emissions ◽

Irrigation Frequency ◽

Water Demands ◽

Gas Diffusivity ◽

Matter Production ◽

Access To Water

Pastures require year-round access to water and in some locations rely on irrigation during dry periods. Currently, there is a dearth of knowledge about the potential for using irrigation to mitigate N2O emissions. This study aimed to mitigate N2O losses from intensely managed pastures by adjusting irrigation frequency using soil gas diffusivity (Dp/Do) thresholds. Two irrigation regimes were compared; a standard irrigation treatment based on farmer practice (15 mm applied every 3 days) versus an optimised irrigation treatment where irrigation was applied when soil Dp/Do was ≈0.033 (equivalent to 50% of plant available water). Cow urine was applied at a rate of 700 kg N ha−1 to simulate a ruminant urine deposition event. In addition to N2O fluxes, soil moisture content was monitored hourly, Dp/Do was modelled, and pasture dry matter production was measured. Standard irrigation practices resulted in higher (p = 0.09) cumulative N2O emissions than the optimised irrigation treatment. Pasture growth rates under treatments did not differ. Denitrification during re-wetting events (irrigation and rain) contributed to soil N2O emissions. These results warrant further modelling of irrigation management as a mitigation option for N2O emissions from pasture soils, based on Dp/Do thresholds, rainfall, plant water demands and evapotranspiration.

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