Enhancing grazing profitability through improving soil health | 2023

Summary

This research saught to better understand two approaches for increasing carbon sequestration levels in pastures. A paired-site study of soil carbon stocks under C4 pastures sown with varying rates of the deep-rooted perennial legume, Progardes® desmanthus suggested that the presence of the legume improved soil carbon levels with a return on investment of 17%, 9% and 3% at the planting rates of 2kg/ha, 4kg/ha and 8kg/ha respectively. These results provide insight into an avenue of increased profitability for graziers and reduced net emissions for the red meat industry.

A further eleven trial sites comprised of two replicates each of three treatments – microbially diverse compost extract, minerals, and compost extract plus minerals – and two controls. Grazing yield was measured and at the conclusion of the trial, each site was sampled for soil carbon and microbiological parameters. Drought and pasture dieback hampered the progress of the trial, and no significant results were found.

Objectives

- Develop a cost effective and environmentally responsible means of improving soil health and increasing soil carbon levels
- Engage a network of producers in improving soil health and further their understanding of business models involving soil carbon and investment in soil productivity
- Further understanding of linkages between various components of the soil health system to enhance sustainable development of the red meat industry
- Build leadership capacity in soil health and C research and adoption;
- Achieve at least a 30% increase in carrying capacity at the farms included in the project

Key findings

The project achieved a number of objectives; however, circumstance such as drought and the Covid-19 pandemic meant the successful completion of other objectives was limited. The results of the research suggest that the incorporation of the Progardes desmanthus legume into C4 perennial pastures, at rates of 2kg/ha, 4kg/ha and 8kg/ha may increase soil carbon sequestered. A planting rate of 2kg/ha showed the best return on investment at 17% pa when framed within the scenario that the additional carbon (less costs and statutory discounts) were traded on today’s carbon market.
No conclusions could be drawn on the application of a microbially diverse compost extract to pastures and the effect on pasture yield, soil carbon or soil health. The results in all areas of the trial were significantly impacted by extended dry conditions and/or pasture dieback.

Benefits to industry

The incorporation of deep-rooted perennial legumes into C4 pastures can have numerous benefits to the red meat industry. Aside from the well-known productivity gains, the greater soil carbon stocks built over time provide the option to gain a return on investment by trading that additional soil carbon on the carbon market. Additionally, the adoption of this practice works towards the industry’s goal of being carbon neutral by 2030.

MLA action

MLA has published the final report to raise awareness of the likelihood of this practice bolstering soil carbon stocks, improve adoptions and move the industry towards its carbon neutral goal.

Future research

MLA will consider repeated measurements of the Progardes trial area to provide insight into sequestration rates over time. This will require additional con-investment to fund this work. Replicates of this trial in other areas will help understand if the results are repeatable in other environments.
Further research needs to be completed on the benefits (or otherwise) of microbially diverse amendments for pastures and soils. To ensure lack of moisture does not confound results, trials should be conducted in irrigated areas. Additionally, work should be done to understand the effectiveness of different methods of applying the amendments before extending the research back into an on-farm commercial scale.