Boosting natural regeneration of the nitrogen capital in grazing lands

Summary

Soil nitrogen (N) is required for pasture growth andreduced nitrogen impacts on pasture production, pasture quality and animal performance. In extensive grazing systems in northern Australia, it’s not possible to boost pasture production by use of nitrogen fertiliser. Production systems have to rely on natural biological fixation to regenerate nitrogen stock in soil. The majority of nitrogen fixation is via soil microorganisms.

This project is evaluating the potential of biological soil crusts (biocrusts) containing soil microbes to fix nitrogen in grazing lands to determine the impact of grazing, spelling and fire practices on nitrogen capture by biocrusts and how it is recycled and made available to plants.

If biocrusts are probable, extension products will be developed to communicate the benefits to producers. Extension materials could include:

• communication materials
• videos showcasing biocrusts and its function
• a smart phone app visualising biocrusts for producers to gauge the biocrust status.

Objectives

The primary objectives of this project are to:

• quantify the nitrogen-generation capacity of biocrusts
• identify the environmental and management factors that drive the presence and activity of biocrusts in different land types
• develop and model different scenarios for N-smart grazing management practices
• generate knowledge to improve nitrogen best practice management (i.e. spelling, stocking and fire regimes) and map next steps (i.e. monitoring, validation on grazing properties).

Benefits to industry

MLA’s feedbase productivity program of work has a focus on underpinning processes to support efficient plant production in the short and longer term. Ensuring required nutrients are available for plant growth (via a range of sources – applied, produced by legumes, mobilised by microbial activity) is key to ensuring a sustainable and profitable red meat industry.