Carbon gains and losses with irrigation, runoff and drainage in cotton farming systems

Theoretical estimates of soil carbon sequestration in Australian farming systems often do not coincide with measured values of soil carbon, possibly due to post sequestration carbon losses (Hulugalle et al. 2013b; Nachimuthu and Hulugalle 2016). Most authors have assumed that this was associated with microbial respiration (Huon et al. 2013). However, although largely overlooked in the past, part of this decline is thought to be due to carbon losses through soil erosion (Chappell et al. 2015; Hulugalle et al. 2013b; Kuhn et al. 2012) and mechanisms associated after the erosion event (Lal 2003). Some losses may also be due to leaching of dissolved organic carbon (DOC) with deep drainage (Nachimuthu and Hulugalle 2016). There is a paucity of empirical studies on the links between crop management practices and carbon movement in terrestrial hydrological pathways in Australian cotton and other irrigated row cropping systems. Thus, predicting carbon stocks using current accounting systems do not fully account for all carbon loss pathways. The purpose of this investigation was to study the impact of a range of management practices on rrigation induced carbon flow in intensive cotton production systems.