Effects of crop residue on carbon dioxide, methane and nitrous oxide emissions on cultivated peat soils

<p>Peatlands cover three percent of the global land surface. However, they store significant amounts of carbon (C), approximately 30%. Peatlands are drained to support agricultural production. It’s estimated that agriculture exploits approximately 20% of peatlands worldwide. The exploited peatlands are significant emitters of carbon dioxide (CO<sub>2</sub>) and nitrous oxide (N<sub>2</sub>O). In Europe, agriculture is the second largest contributor of greenhouse gas (GHG) emissions. In addition to GHG emissions, we are fast losing productive peatlands; it’s estimated by 2050, a third of productive peatlands will be lost. Loss of productive peatlands will affect productivity and food security.</p><p>To prolong use of peatlands, ploughing in of crop residue, either from the previous season or specially grown crop, is often considered a mitigation option. Nevertheless, there is concern that fresh organic matter (FOM) might accelerate decomposition of existing organic. This study assesses effects of FOM on the emissions of CO<sub>2</sub>, methane (CH<sub>4</sub>) and N<sub>2</sub>O in a cultivated peatland. A mesocosm experiment was carried out using intact cores with added FOM and manipulated water table (WT), -20 and -50 cm.</p><p>The results show there is an effect of both WT and FOM on emissions. CO<sub>2</sub>, CH<sub>4</sub>, and N<sub>2</sub>O emissions differ in the different WT treatments. The -20 cm cores produced more methane than the -50 cm.  It is evident that leaving crop residue and then ploughing it in does not have the desired effect as it led to increased emissions.</p>