Greenhouse Gas Fluxes in A Tillage Chronosequence.

Accumulation of the greenhouse gases (GHG) carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) in the atmosphere contributes to the “greenhouse effect” on the earth. In recent years, numerous assessments have been made to evaluate the potential of croplands to offset GHG emissions from the transportation, energy and industrial sectors. No-tillage (NT) farming is a method of producing crops without tillage other than the small amount of soil disturbance that occurs at time of planting. Long-term maintenance of no-tillage has been suggested as being more effective in reducing GHG than intermittent no-tillage, but there is a paucity of field-based data regarding the long-term impacts of no-till on GHG fluxes. We conducted a study comparing GHG fluxes from no-tillage or plow tillage soils, that were carefully chosen to represent a chronosequence, consisting of croplands in a corn-soybean rotation for 7, 11 and 46 years. An untilled forested control soil area was also included at each site. Preliminary results revealed highest CO₂ fluxes from the soil to atmosphere were observed in forest and plow tillage soils. The highest CH₄ fluxes from the soil to the atmosphere were observed in PT soil and the lowest CH₄ fluxes from the forest soils. The highest N₂O fluxes from the soil to the atmosphere were observed from PT soil and the lowest fluxes from the forested soils. Combining results for all three greenhouse gases suggest that the relative global warming mitigation potential for long-term maintenance of no-tillage soil is less than for plow tillage soil and only slightly different than for forested soil.

 Acknowledgement:The authors appreciate support received from (1) The TUBITAK Scholarship Program, (2) The Ohio State University/The Ohio Agriculture Research and Development Center, (3) the Climate, Water and Carbon Program, and (4) a grant received from the USDA-CSREES titled “Greenhouse gas budget and methane dynamics in a no-tillage chronosequence.”