Soil nitrous oxide emissions in irrigated cotton are reduced by nitrification inhibitors applied with pre-plant anhydrous ammonia

2016

Research organisaton
Funding sources

Trial details

Researcher(s) Annabelle McPherson (NSW DPI)
Graeme Schwenke (NSW DPI)
Year(s) 2016
Contributor Department of Primary Industries NSW
Trial location(s) Gunnedah, NSW
Emerald, QLD
Further information View external link
Soil nitrous oxide emissions in irrigated cotton are reduced by nitrification inhibitors applied with pre-plant anhydrous ammonia locations
Aims

To assess the efficacy of two nitrification inhibitors, 3,4-dimethylpyrazole (DMP) and nitrapyrin, when applied directly into the anhydrous ammonia stream during pre-plant nitrogen (N) application for commercial irrigated cotton production.

Key messages
  • N2O emissions at the Gunnedah site were approximately 10 times higher than at the Emerald site, due to the wet soil conditions and high pre-season rainfall at Gunnedah which led to denitrification of N from pre-season anhydrous ammonia application.
  • Two nitrification inhibitors, DMPS (“Big N-sure”, Incitec Pivot Fertilisers) and nitrapyrin (“N-serve”, Dow AgroSciences) directly injected into anhydrous ammonia during pre-plant N application delayed the conversion of applied ammonium in the soil to nitrate for a period of 2–3 months.
  • At the Gunnedah site, cumulative N2O emitted was reduced by 86% (DMPS) and 65% (nitrapyrin), compared to untreated ammonia.

Conclusions: 

In a season such as that experienced at the Emerald 2016–17 site, there were only minor environmental benefits from using a nitrification inhibitor in conjunction with anhydrous ammonia. However, these experimental conditions may not be typical as pre-plant fertiliser is usually applied earlier in the year at Emerald than it was at this site. A longer period of time between pre-plant application and plant establishment would provide greater opportunity for N2 O losses to occur, although the potential for heavy winter rainfall tends to be low in the Emerald region. While both inhibitor products clearly reduced emissions during the first two measurement periods, it was apparent that the effectiveness of these products had dissipated by the time of the second irrigation. The additional inhibitor application with the side-dressed urea boosted the N2 O reduction period for the DMPP treatment, while the application of untreated urea to the other treatments allowed further losses matching those of the untreated control after the initial pre-plant N application. The 2016–17 Gunnedah experiment provided the perfect testing conditions for nitrification inhibitors as the soil was very wet at application, and received frequent heavy rainfall during the next 3 months. These inhibitors were designed to retain mineral N from applied N fertiliser in the soil during periods of excessive rainfall that may otherwise lead to large losses of nitrate N through denitrification and leaching. Leaching occurs through downward movement of nitrate with water in the soil, but we found no evidence of this having occurred in the soil core samples we took just prior to sowing. For heavy clay soils such as this one at Gunnedah, denitrification of soil nitrate during periods of anaerobic soil conditions is the most likely major N loss pathway. The results of the gas sampling campaigns highlighted the almost complete mitigation of N2 O emissions during this period by adding nitrification inhibitors. The Big N-sure® inhibitor appeared to remain active for longer in the soil than the N-serve®.

Lead research organisation Department of Primary Industries NSW
Host research organisation N/A
Trial funding source DPI NSW AOTG14013; 2013–17
Trial funding source DAWR AOTG14013; 2013–17
Related program Determining optimum nitrogen strategies for abatement of emissions for different irrigated cotton systems
Acknowledgments

This experiment was part of the project Determining optimum nitrogen strategies for abatement of emissions for different irrigated cotton systems (AOTG14013; 2013–17), with joint investment  by NSW DPI and DAWR, and administered by CRDC. Thanks to Ross Burnett and Rod Smith for providing the experimental sites and for applying the anhydrous ammonia and urea in field, and to Amanda Noone for carrying out the field work at Emerald, Pete Perfrement, Tim Grant and Wayne McPherson at Gunnedah. Technical assistance with the application of both inhibitors was provided by the Incitec-Pivot Big-N team and is gratefully acknowledged. Incitec-Pivot provided the Big N-sure® inhibitor and ENTEC®-urea, and Dow Agrosciences provided the N-serve® inhibitor. All soil and plant N analyses were carried out by Clarence Mercer in the ISO9001-accredited laboratory at Tamworth Agricultural Institute, NSW DPI.


Other trial partners Co-operators: Ross Burnett (Emerald), Rod Smith (Gunnedah), Incitec-Pivot Big-N team
Download the trial report to view additional trial information

Method

Crop type Other crop: Cotton
Treatment type(s)
  • Fertiliser: Application Method
Trial type Experimental
Trial design Randomised,Replicated,Blocked

Gunnedah 2016

Sow date 20 August 2016 The Emerald site was sown with Sicot 746B3F on 20 August 2016. The Gunnedah site was sown with Sicot
Harvest date 13 February 2017 Cotton picking at Emerald was on 13 February 2017. Picking at Gunnedah was not yet done at the time
Plot size Not specified
Plot replication 3
Plot blocking Randomised complete block
Plot randomisation Randomised complete block design with three treatments (T1 = ammonia, T2 = ammonia + DMPS [Big N-sure®], T3 = ammonia + nitrapyrin [N-serve®]) and three replications. A Raven SideKick Pro direct injection system was used to apply nitrification inh

Emerald 2016

Sow date Not specified
Harvest date Not specified
Plot size Not specified
Plot replication Not specified
Plot blocking Not specified
Plot randomisation Not specified
Download the trial report to view additional method/treatment information
Trial source data and summary not available
Check the trial report PDF for trial results.
Observed trial site soil information
Trial site soil testing
Not specified
Soil conditions
Trial site Soil texture
Gunnedah, NSW Black vertisol
Emerald, QLD Not specified
Derived trial site soil information
Australian Soil Classification Source: ASRIS
Trial site Soil order
Gunnedah, NSW Sodosol
Emerald, QLD Kandosol
Soil Moisture Source: BOM/ANU
Average amount of water stored in the soil profile during the year, estimated by the OzWALD model-data fusion system.
Year Gunnedah NSW Emerald QLD
2016 28.1mm463.1mm
2015 40.8mm410.7mm
2014 31.3mm392.5mm
2013 75.3mm446.4mm
2012 122.9mm575.8mm
2011 67.2mm595.3mm
2010 91.3mm585.6mm
2009 21.8mm527.6mm
2008 35.8mm546.8mm
2007 31.8mm478.3mm
2006 22.3mm393.6mm
2005 54.0mm358.3mm
2004 61.3mm286.2mm
2003 135.8mm276.1mm
2002 196.3mm363.1mm
2001 354.8mm525.4mm
2000 415.6mm593.0mm
National soil grid Source: CSIRO/TERN
NOTE: National Soil Grid data is aggregated information for background information on the wider area
Actual soil values can vary significantly in a small area and the trial soil tests are the most relevant data where available

Soil properties

Loading

Climate

Derived climate information

No observed climate data available for this trial.
Derived climate data is determined from trial site location and national weather sources.

Gunnedah QLD

Emerald QLD

Gunnedah QLD

NOTE: Exact trial site locality unknown - Climate data may not be accurate
Loading
Loading
Loading

Emerald QLD

NOTE: Exact trial site locality unknown - Climate data may not be accurate
Loading
Loading
Loading

Some data on this site is sourced from the Bureau of Meteorology

SILO weather estimates sourced from https://www.longpaddock.qld.gov.au/silo/
Jeffrey, S.J., Carter, J.O., Moodie, K.B. and Beswick, A.R. (2001). Using spatial interpolation to construct a comprehensive archive of Australian climate data , Environmental Modelling and Software, Vol 16/4, pp 309-330. DOI: 10.1016/S1364-8152(01)00008-1.

Trial report and links

2016 trial report

2016 trial report



Trial last modified: 16-09-2019 12:56pm AEST