P.PSH.1195 - Measuring soil carbon in grazing systems

Summary

Increasing soil organic carbon (SOC) through improved grazing management practices is tightly linked to increasing soil health, drought resilience and the sustainability and profitability of Australia’s pastoral industry. Recent policy changes by the Australian Government have resulted in the fast tracking of innovative soil management practices in grazing systems as a priority for reducing the nation’s greenhouse gas emissions. By storing carbon in soils, graziers can gain soil carbon credits, which can provide an additional income stream, as well as align themselves with the Australian Red Meat Industry’s carbon neutral initiative (CN30). This research will examine the use of eddy covariance flux towers to measure the impact of time-controlled grazing on soil health, soil carbon, and water use efficiency. The outputs of the project provide a foundation for further work under projects P.PSH.2104 and P.PSH.2126. By significantly reducing the costs of soil carbon measurement (currently around $20–$30 ha) and increasing the certainty in the rate of carbon (C) sequestration in Australian grazing systems, producers will gain greater clarity on the financial upside of carbon farming.

Objectives

• Confirm changes in SOC in response to grazing management at scale from two flux towers in Goondiwindi.
• Determine how this information can be used in the development of predictive models for pasture productivity and soil carbon change in response to climate and soil type.
• Develop a cost-effective and scalable solution to measure SOC and enable producers to better manage soils and generate soil carbon credits.
• Preliminary outcomes to the objectives have been achieved but methods require further refinement under projects P.PSH.2104 and P.PSH.2126 which are still ongoing.
  
  

Key findings

Eddy covariance flux towers have the ability to generate robust and defensible annualised estimates of ecosystem C exchange over large spatially averaged areas (up to 50ha) suitable for a C accounting environment. More work needs to be done in projects P.PSH.2104 and P.PSH.2126 to account for C in different pools to determine the annualised C account from NEE. Above-ground biomass, below-ground roots and tree carbon must all be subtracted from NEE to determine soil carbon stocks.

Benefits to industry

This project provides the foundation to develop a cost-effective and scalable solution to measure SOC to inform producer decision making and generate an income stream through carbon farming.

MLA action

No further MLA Action required.

Future research

The findings from this project will be used to inform work in projects P.PSH.2104 and P.PSH.2126.