Soil carbon benefits in grazing systems

Soil carbon benefits in grazing systems

Whole farm systems analysis from the WFSAM project

Researchers investigated the on-farm benefits of soil carbon accumulation following a transition in land use from cereal cropping to grazed pasture. The impact of increased soil carbon on pasture production (due to changes in soil nitrogen mineralisation and plant available water holding capacity (PAWHC)) was measured at two different soil carbon starting points (high and low), on two soil types in two climatic zones.

Over the 20-year simulation:

  • Soil organic carbon accumulation was faster in low carbon soils (0.3-0.48 t C / ha / yr) compared to their high carbon counterparts (0.02-0.23 t C / ha / yr)
  • The increased pasture production associated with higher soil carbon was valued at $42.51-$157.19 / ha
  • The entire value on low rainfall sites ($42.51-$133.54 / ha) was attributable to increased PAWHC.
  • On high rainfall sites, increased nitrogen mineralisation increased pasture production on high carbon soils. The increase in N mineralisation on high rainfall sites was valued at $85.03-$95.61 / ha.

The comparisons between high and low carbon soils suggest that the direct farm benefits of high soil carbon on nitrogen mineralisation and associated pasture production alone are substantial. These on-farm benefits are far more compelling motivation for increased soil carbon than the trading of this additional carbon in national or international carbon markets, given likely prices, risks associated with permanence rules, and in particular the monitoring, reporting and verification overheads.

Primary researchers

  • Richard Eckard, PICCC
  • Rachelle Meyer, University of Melbourne
  • Brendan Cullen, University of Melbourne

Publications

Meyer RS, Eckard RJ, Cullen BR, Johnson IM (2015). Process modelling to assess the sequestration and productivity benefits of soil carbon in grazing systems. Agriculture, Ecosystems and Environment, 213, 272–280, DOI: 10.1016/j.agee.2015.07.024.

Meyer RS, Cullen BR, Eckard RJ (2016). Modelling the influence of soil carbon on net greenhouse gas emissions from grazed pastures. Animal Production Science, 56, 585-593, http://dx.doi.org/10.1071/AN15508.

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