Sampling methodology for estimating the impacts of pasture type and management on soil carbon stocks in grazing lands

Summary

​In addition to measurement of total soil organic carbon stocks, the measurement of carbon fractions, particulate organic carbon (POC) and humus (HUM) was intended to provide important information relating to turnover rates of carbon in the soil. These include: the roles different soil C fractions contribute towards soil health and plant productivity, carbon sequestration and the potential influence of soil carbon stock changes for measurement and monitoring purposes.

By the time of this project, this MLA-funded project has:

(i) undertaken and published a critical review of sampling designs for the measurement of soil organic carbon in grazing lands;

(ii) developed a recommended sampling strategy for measurement of soil carbon in grazing lands based upon soil type, sampling scale, number and location of sampling points (published in peer-review journal);

(iii) applied the recommended sampling methodology outlined above to assess SOC stocks in paddocks with varied grazing management (cell, rotation, continuous stocking and fire frequency and intensity), including northern Australian rangelands as part of the national Soil Carbon Research Program;

(iv) reported findings of SOC stock and management effects from long-term grazing and leucaena research trials (Wambiana and Brian Pastures); and

(v) provided recommendations for ongoing research efforts of soil carbon stock measurement in Australian rangelands.

Using Wambiana long-term Research trial data from this project, we continued this work beyond total soil organic carbon assessment, to consider sampling methodology and statistical analysis of the soil organic carbon fractions, in accordance with national soil carbon research activities.​