Identifying the causes of unreliable nitrogen fixation by medic based pastures

2017

Research organisaton
Funding source

Trial details

Aims

The broad aim of this 3 year SAGIT funded project was to investigate if current management tools for medic based pastures, such as herbicides, fertilisers and rhizobial inoculants, are affecting N fixation by medic pastures under field conditions typical of the upper Eyre Peninsula.

Key messages
  • Applying phosphorus to a soil with low P reserves when establishing a medic pasture boosts shoot and root dry matter, improves root health and improves N fixation.
  • The addition of urea at seeding can reduce nodulation in medic pastures.
  • Residues of the herbicide Logran can severely stunt medic growth.
  • Applying a full label rate of Agritone 750 (late) decreases pasture production and N fixation in actively growing pastures.
  • Any management practice that reduces medic biomass will reduce N fixation, such as the late application of certain herbicides, eg Agritone 750.
  • In a dry growing season when medic plants are already moisture stressed, herbicides will have little impact on medic production and N fixation.
  • Regardless of seasonal conditions, the management of newly established medic pastures with regard to herbicides and nutrition, appears to have no impact on the yield and protein levels of the wheat crop in the following year.
Lead research organisation SARDI Minnipa Agricultural Centre
Host research organisation N/A
Trial funding source SAGIT 515
Related program N/A
Acknowledgments

Thank you to Greg Scholz, Brent Cronin and their families, for allowing us to conduct the trials on their properties and their support of research; and Andy Bates (Bates Ag Consulting) for his valuable input.


Other trial partners Not specified
Download the trial report to view additional trial information

Method

Crop type Pasture: Medic
Treatment type(s)
  • Fertiliser: Rate
  • Herbicide: Timing
  • Herbicide: Type
Trial type
Trial design

Minnipa Agricultural Centre 2017

Sow rate or Target density Not specified
Sowing machinery Not specified
Sow date Not specified
Harvest date Not specified
Plot size Not specified
Plot replication Not specified
Fertiliser Not specified
Herbicide Not specified

Piednippie 2017

Sow rate or Target density 10 kg/ha
Sowing machinery

Two replicated field trials were established on the Eyre Peninsula in 2017. One on a red sandy loam, representative of typical Mallee environments in SE Australia (Minnipa Agricultural Centre Airport) and the other on a grey highly calcareous sandy soil (Brent Cronin’s property at Piednippie).

The 2017 medic trials were dry sown with inoculated Herald strand medic at 10 kg/ha, on 6 June (Minnipa) & 7 June (Piednippie). The GSR at Minnipa was only 155 mm, with most of that rain falling in July and August. All nutrition treatments (Table 1) were applied at sowing. Treatments to simulate herbicide residues were imposed immediately after sowing.

The early post emergent herbicide treatments were applied when the medic plants reached their third trifoliate leaf stage on 21 August (Minnipa) & 24 August (Piednippie). Due to the lack of early season rainfall and poor seasonal conditions this was much later on the cal

Sow date 7 June 2017
Harvest date Not specified
Plot size 8m X 1.5m
Plot replication 3
Fertiliser
  • 10 kg/ha Phosphorus (Phosphoric acid)
  • 10 kg/ha Phosphorus + 100 ml/ha Tigrex (Phosphoric acid + 570 g/L MCPA as the ethylhexyl ester; 25 g/L Diflufenican) + 200 ml wetter
  • 10 kg/ha Phosphorus + 250 ml/ha LVE Agritone (Phosphoric acid + 570 g/L MCPA as the 2-ethylhexyl ester) + 200 ml wetter
  • 10 kg/ha Phosphorus + 200 ml/ha Agritone 750 Late (Phosphoric acid + 750 g/L MCPA as dimethylamine salt) 
  • 2 kg/ha Zinc (Zinc Sulphate)
Herbicide

Residues

  • 45 ml/ha Intervix (33 g/L Imazamox; 15 g/L Imazapyr)
  • 1.75 g/ha Logran (750 g/kg Triasulfuron)
  • 7.5 ml/ha Intervix (300 g/L Clopyralid as triisopropanolamine salt)

Post Emergent

  • 100 ml/ha Tigrex Early (250 g/L MCPA as the ethylhexyl ester; 25 g/L Diflufenican) + 200 ml BS1000 wetter
  • 100 ml/ha Tigrex Late (250 g/L MCPA as the ethylhexyl ester; 25 g/L Diflufenican) + 200 ml BS1000 wetter
  • 250 ml/ha LVE Agritone Early (570 g/L MCPA as the 2-ethylhexyl ester) + 200 ml BS1000 wetter
  • 250 ml/ha LVE Agritone Late (570 g/L MCPA as the 2-ethylhexyl ester) + 200 ml BS1000 wetter
  • 200 ml/ha Agritone 750 Early (750 g/L MCPA as the dimethylamine salt)
  • 200 ml/ha Agritone 750 Late (750 g/L MCPA as the dimethylamine salt)

Pingbong 2017

Sow rate or Target density Not specified
Sowing machinery Not specified
Sow date Not specified
Harvest date Not specified
Plot size Not specified
Plot replication Not specified
Fertiliser Not specified
Herbicide 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
Minnipa Agricultural Centre, SA Not specified
Piednippie, SA Grey calcareous sandy loam
Pingbong, SA Not specified
Derived trial site soil information
Australian Soil Classification Source: ASRIS
Trial site Soil order
Minnipa Agricultural Centre, SA Calcarosol
Piednippie, SA Calcarosol
Pingbong, SA Calcarosol
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 Minnipa Agricultural Centre SA Piednippie SA Pingbong SA
2017 364.0mm158.1mm396.4mm
2016 332.8mm168.5mm359.6mm
2015 297.6mm138.7mm355.6mm
2014 359.2mm162.0mm418.8mm
2013 293.9mm130.5mm339.4mm
2012 327.9mm128.2mm392.1mm
2011 370.8mm159.1mm402.6mm
2010 361.5mm146.5mm397.2mm
2009 368.6mm162.3mm391.9mm
2008 286.4mm137.7mm318.6mm
2007 291.5mm115.4mm339.2mm
2006 325.4mm139.5mm339.2mm
2005 292.1mm132.4mm312.3mm
2004 289.8mm133.5mm305.0mm
2003 302.0mm137.1mm323.1mm
2002 301.6mm127.4mm332.8mm
2001 343.8mm143.0mm396.6mm
2000 351.6mm145.7mm424.6mm
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

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Climate

Piednippie SA 2017


Observed climate information

Rainfall avg ann (mm) 379mm
Rainfall avg gsr (mm) 304mm
Rainfall trial total (mm) 247mm
Rainfall trial gsr (mm) 199mm

Derived climate information

Minnipa Agricultural Centre SA

Piednippie SA

Pingbong SA

Minnipa Agricultural Centre SA

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Piednippie SA

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

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

2017 trial report

2017 trial report



Trial last modified: 08-10-2019 12:00pm AEST