A 12-year University of Illinois study has found that cover crops, in combination of three types of tillage, can increase the amount of sequestered soil organic carbon.
U of I soil scientist Ken Olson evaluated plots that were subjected to no-till, chisel plow and moldboard plow treatments with and without hairy vetch and cereal rye cover crops.
"By 2012, we found that the soil tillage plots that had cover-crop treatments had more soil organic carbon stock than those without cover crops for the same soil root zone and tillage treatment," Olson said.
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In fact, Olson said that the no-till system, with cover crops, sequestered the most soil organic carbon when compared to the pre-treatment from the year 2000 no-till baseline soil organic carbon stock.
"In addition, the no-tilled, chisel plowed, and moldboard-plowed plots with cover crops all sequestered soil organic carbon above the pre-treatment baseline levels of the same tillage treatment."
With the addition of cover crops to all tillage treatments for the 12-year study, the soil organic carbon stock gains were 30% higher for no-till, 10% higher for chisel plowed, and 18% for moldboard-plowed plots.
"This suggests that soil organic carbon stock losses from tillage, water erosion, and some disturbance or mixing during no-till planting, aeration, nitrogen injection in corn years, and mineralization were less than the soil organic carbon gain from the cover-crop treatment," Olson said.
Olson stressed that establishing a baseline of soil organic carbon prior to the study is critical in order to claim that soil organic carbon is truly being sequestered
"Management practices, such as no-till and cover crops, must create an increase in net soil organic carbon from a previous pre-treatment baseline, as well as result in a net reduction in atmospheric carbon dioxide levels to be described as having sequestered soil organic carbon," Olson said.
The study was conducted at U of I's Dixon Springs Agricultural Research Center in southern Illinois beginning in 2001 on sloping ground with a moderately well drained, eroded soil.
Source: University of Illinois