Farm Table says:
What is the problem?
Soil organic carbon (SOC) has been identified as a possible C sink for sequestering atmospheric carbon dioxide. Limited data are available on the impact of management practices on the rate of SOC change in agricultural soils in Australia.
What did the research involve?
This paper involves three separate experiments over the course of 13-25 years located near Wagga Wagga in temperate Australia to assess C dynamics under different tillage and stubble management practices, and under cropping intensities in pasture/crop rotations.
What were the key findings?
Results confirm the importance of management practices and pasture in determining first the steady-state SOC concentrations that are characteristic of given rotations and crop management systems, and second the rates of change of SOC concentrations as the approach steady-state concentrations in agricultural soils of this agro-ecological zone. Under continuous cropping, even under conservation agriculture practices of no-tillage, stubble retention, and crop rotation, the initial SOC stock present after a long-term pasture phase was, at best, maintained but tended to decrease with increased tillage or stubble burning practices. The effect of tillage was greater than that of stubble management. Increases in SOC were observed only in rotations incorporating a pasture phase.
Historical soil organic carbon data from the three experiments confirm the importance of management practices, and initial SOC concentration, in determining the rate and direction of change of SOC concentration in agricultural soils of the agro-ecological zone. Results also highlight the importance of the pasture phase in maintaining or increasing SOC under pasture/crop mixed farming systems.