Increasing soil organic carbon is promoted as a strategy for sequestering carbon dioxide and mitigating anthropogenic greenhouse gas emissions. Increasing soil carbon can benefit crop productivity; however, there is a risk that it may also enhance nitrous oxide emissions, a potent greenhouse gas. Understanding how increasing soil carbon effects soil nitrous oxide emissions and crop production is needed when assessing the suitability of soil carbon sequestration for abating GHG emissions. The effect of increasing soil carbon on nitrous emissions from sandy-textured soils in Australia’s rain-fed cropping regions is poorly understood.
The overall objective of this project is to investigate if increasing the soil carbon alters nitrous emissions. The effect of soil carbon on nitrous oxide is being investigated a long term study site in the Western Australian grainbelt. The study site was established in 2003 by the Liebe Grower Group, and it includes experimental plots where total soil carbon concentrations have increased by up to 45% via organic matter inputs. The study site provides a unique opportunity to investigate the interaction between soil carbon and nitrogen fertiliser inputs on greenhouse gas emissions without the confounding influence of climate and soil type.
Soil nitrous oxide emissions are being continuously measured for 2.5 years using an automated chamber system. The experimental design includes two contrasting soil carbon treatments and two nitrogen fertiliser treatments.
Field plots were planted to canola (2012), barley (2013), and oats (2014) each winter, with the plots remaining fallow between each. Additional soil, crop and climatic data are being collected to help explain the observed nitrous oxide emissions. Data is progressively being uploaded onto the National Australian Nitrous Oxide Research Program data repository. Data is being provided to researchers assessing models for predicting nitrous oxide emissions from soil.
Understanding how increasing soil carbon effects soil nitrous oxide emissions and crop production will enable Professor Barton to assess the suitability of soil carbon sequestration for abating greenhouse gas emissions from land.
- Klaus Butterbach-Bahl, Institute for Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU), Karlsruhe Institute of Technology, Germany