Short-term impacts of different tillage practices and plant residue retention on soil physical properties and greenhouse gas emissions

Abstract

Reducing tillage intensity and plant residue retention have the potential to mitigate climate change by reducing soil greenhouse gas emissions. Few comparative studies have explored the effects of different tillage practices and plant residue retention on the net balance of GHG emissions in the short term (1–2 years). We hypothesised that reducing tillage and plant residue retention decreases GHG emissions compared to conventional ploughing and residue removal. We estimated the effects of different tillage practices; no-tillage, minimum-tillage and traditional ploughing as well as plant residue retention on; 1) bare-soil GHG emissions, 2) the net ecosystem exchange (NEE), and ultimately, 3) the potential for climate change mitigation, CO2 equivalent. GHG fluxes were measured using the static chamber method and soil physical properties were assessed using X-ray Computed Tomography (CT) and a range of traditional methods. No-tillage increased bulk density and shear strength compared to minimum-tillage and ploughed soil. Soil moisture content and organic matter content at 0−5 cm depth were higher in no-tillage and minimum-tillage compared to ploughed soil. No-tillage increased soil−CO2 emissions and CH4 uptake but reduced NEE−CO2 emissions and increased NEE−CH4 uptake. No and minimum-tillage resulted in 56 % and 40 % reduction in CO2 equivalent emissions respectively compared to ploughing for the combined crop-soil measurements. Changes in the CH4 and CO2 were interlinked to changes in soil pore architecture and physical properties. Taken together our data demonstrate that no-tillage and minimum-tillage have potential to contribute to climate change mitigation through reducing GHG emissions.