Greenhouse in Agriculture - Mixed Farming Systems

Decreasing Nitrous Oxide Emissions from High Rainfall Cropping Systems

Project Leader: John Graham

Other Scientists: Sally Officer, Kevin Kelly, Penny Riffkin

Objectives: To Measure the effects of:

  • Conventional and minimal tillage and
  • Nitrogen inhibitors on N2O emissions from a legume crop rotation system. and:
  • Provide information that will enable an improved understanding of the impact of different management and mitigation options on the N2O emissions, N cycling and productivity of legume/ pasture - cropping system in the HRZ of Victoria

Nitrous oxide (N2O) is a powerful greenhouse gas with a global warming potential 310 times that of carbon dioxide (CO2). Agriculture accounts for 84% of N2O emissions due to cultivation (38%), fertilizer (32%) and animal waste (30%). Cropping in the high rainfall zone (HRZ) is rapidly expanding, where N2O emissions in excess of 3 kg N2O-N ha-1 yr-1 (930kg CO2 equivalents) have been measured when a high fertility legume pasture was cropped with wheat.

The project will (i) evaluate methods of mitigating N2O emissions from direct and conventionally sown legume/wheat rotations and (ii) the efficacy N inhibitors (such as DCD) in such rotations, using automated chambers connected to a tunable diode laser (TDL) to constantly monitor N2O emissions.

The project will result in options for practice change in the farming community that reduce emissions and information to inform models such as NCAS for industry and government decision makers.

A tunable Diode Laser (TDL) and a Licor in conjunction with 12 automated chambers will measure N2O and CO2 emissions respectively from treatments described below.A permanent mixed ryegrass/phalaris/sub-clover pasture will be sprayed to eradicate the grass and promote legume dominance.

Minimum and conventional tillage as well as a nitrification inhibitor will be examined, giving 4 treatments, replicated 3 times.

The treatments are:-

  • Conventional full tillage without nitrification inhibitor

  • Conventional full tillage with nitrification inhibitor

  • Minimal tillage using direct drilling without nitrification inhibitor

  • Minimal tillage using direct drilling with nitrification inhibitor

Commencement date: April 2009     Completion date: June 2012

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