The demand for sustainable agriculture practices has been growing steadily, prompting growers to explore alternative methods to meet their crops’ nitrogen needs. Traditional synthetic nitrogen fertilisers, once widely relied upon, are losing favour due to their increasing costs and substantial greenhouse gas emissions during manufacturing.

In response, growers are turning to organic nitrogen sources as a more environmentally friendly and cost-effective solution. However, while the general principles of nitrogen mineralisation from organic sources are well known (for example, the impact of soil temperature, moisture, and organic carbon to nitrogen ratios), managing organic nitrogen to meet crop demands remains a challenge.

To support growers interested in adopting organic nitrogen sources, the demonstration trial at Mulgowie Farming Company in Queensland’s Lockyer Valley will:

  • Monitor seasonal soil nitrate and ammonium levels and how they relate to soil temperature and moisture under different organic nitrogen sources (compost and legume cover crops) and management practices.
  • Trial practical ways of managing organic nitrogen sources to better match vegetable crop needs.

Pictured above: The new demonstration site at Mulgowie Farming Company, Queensland.

Progress so far

In June 2023 the Mulgowie team planted a faba bean cover crop ready for ongoing treatments and monitoring, which will be followed by a sweet corn crop.

Over the coming months, soil temperature and moisture probes, installed in various treatment areas, will be monitored. Ongoing soil sampling will measure changes in nitrate and ammonium levels over time.

Treatments include:

  • Faba bean crop incorporated green
  • Faba bean crop terminated with herbicide and left brown on soil surface
  • Faba bean crop harvested for grain
  • Fallow (control)
  • Areas with and without compost

Stephanie Tabone from the Soil Wealth ICP team is excited to be working with Mulgowie on the demonstration and thanks the team for their involvement.

L-R: Nodules on roots of faba bean crop; installation of soil moisture probes.