PICCC PhD graduate: Rachelle Meyer

Rachelle MeyerRachelle recently completed her PhD at UM, supervised by Richard Eckard and Brendan Cullen. Rachelle's thesis explored the use of a whole-farm system modelling approach to quantify the agro-ecosystem benefits and mitigation implications of soil carbon in grazing systems of western Victoria in both recent and future climates.

Rachelle has published two papers on this topic, and provided the following summary:

We investigated both the on-farm benefits and the net greenhouse gas balances of maintaining high levels of soil organic matter (SOM) using a whole-farm system modelling. We looked at two pasture scenarios: high SOM, where initial carbon amount was similar to long-term pasture; and low SOM, where initial carbon condition was similar to long-term cropping with annual cultivation.

The analysis compared mineralisation, plant-available water-holding capacity (PAWHC), associated productivity and net greenhouse gas balances between the high- and low-SOM soils with the same management, each in two climatic zones and with two soil types.

Some of the key findings included:

These results indicate that soil carbon sequestration, through increased SOM, can provide substantial on-farm benefits that contribute to future productivity. However, as SOM increases there is a trade-off between diminishing greenhouse gas offsets and increasing ecosystem services, including mineralisation and productivity benefits.

Read more about Rachelle’s research in her published papers: