P.PSH.2104 - Time controlled grazing for soil carbon sequestration and improved ecosystem services

Summary

Time-controlled grazing (TCG) has been promoted for its potential to improve soil health, pasture productivity, and livestock performance. However, its adoption in Australia has been limited due to conflicting scientific evidence.

This study provides a farm-scale assessment of TCG's impact, focusing on soil organic carbon (SOC) sequestration and biodiversity. Ideally, long-term trials (15+ years) with established baseline conditions would be conducted to evaluate these effects. In the absence of such trials, a paired-site approach was used, comparing TCG-managed farms with conventionally managed farms matched for land use history, soil type, and vegetation.

Objectives

• To quantify differences in soil organic carbon (total carbon stocks, stable and labile SOC fractions) between conventional grazing and TCG in subtropical systems in the Brigalow Belt bioregion.
• To quantify biodiversity generated with different grazing management.
• To qualitatively assess differences in producer wellbeing.

Key findings

• Soil organic carbon stocks were significantly greater with time controlled grazing in comparison to conventionally grazed systems in four out of five paired trials across vertosol soils in the Brigalow Belt bioregion.
• N stocks were 27% greater in TCG systems than in continuously grazed systems.
• Insect diversity was improved under TCG, but had no difference to biodiversity outcomes for birds which were more determined by proximity to woodland.

Benefits to industry

The research demonstrated that SOC was significantly greater (~17.7 t C/ha) on TCG farms in the Brigalow Belt bioregion (measured after 20+ years of TCG implementation) than on conventional grazing systems, possibly indicating a long-term potential for SOC accumulation through the implementation of combined management practices such as those used in TCG systems (cell based grazing, adaptive grazing methods based on pasture production, shorter grazing/longer resting periods).

MLA action

MLA will incorporate this research into its extension materials to continuously improve producer training resources such as CarbonEDGE.

Future research

We have demonstrated the proof-of-concept for generating high resolution data on soil carbon storage (flux towers) and ecosystem outcomes (ecoacoustics) at the property scale. The recommended next step is to incorporate these state-of-the-art observation tools into a nationally consistent framework for sustainable grazing management that can rapidly assess innovation and drive on-the-ground change. This will allow producers to access independent data on the impacts of management change and the potential for soil carbon sequestration in their region.