Quantifying the carbon gains from mixed cropping systems

In north-east Victoria and southern NSW, two soil properties influence soil health and productivity in a significant way — soil pH and soil organic carbon (SOC).

Soil pH plays an important role in governing the chemical environment in the soil, while soil organic carbon (SOC) is a key component of soil organic matter (SOM) and plays many important roles in maintaining soil health.

This project aimed to quantify the baseline variance in soil pH and soil organic carbon (SOC) in four cropping paddocks and four pasture paddocks in north east Victoria, to understand the degree to which these parameters may vary in paddocks that appear relatively uniform.

Soil organic carbon also contributes much to our soil and farming systems and mechanisms are now in place, through the Federal Government Emission Reduction Fund, to pay farmers to maintain an increase in SOC, via the Carbon Farming Initiative. This project sought to provide further information for growers looking to understand more about this process.

Because the calculation of carbon stocks is more difficult in practice than in theory, and because there is a lack of regionally relevant reference data available for growers, the collection of soil samples using protocols from the Carbon Farming Initiative also aimed to provide a regionally relevant example of how to conduct this work, as well as a guide to likely local SOC stocks.

The project also aimed to calculate the benefit that could be ascribed to an SOC increase of 0.5% (within a 25-year contracted period), using data collected for one of the project paddocks.

The final report is available to download here; Quantifying in-paddock variation of soil organic carbon and pH in north-east Victoria

The project team would like to thank the participating growers for their willingness to contribute to this work.