Ploughing into the effect of crop tillage on greenhouse gas emissions
A team from the United States Department of Agriculture's Agricultural Research Service (USDA-ARS) in partnership with the University of Minnesota has found that the tillage of crops can affect levels of greenhouse gas emissions over a specified area of land.
Tillage, they discovered, lowers the amount of nitrous oxide released into the atmosphere per hectare. This is significant, as it is not well known that nitrous oxide is one of the most potent greenhouse gases, trapping up to 300 times more heat that carbon dioxide.The report from the Journal of Environmental Quality suggests that we should be measuring greenhouse gas emissions by crop yield rather than by acreage. The team, headed by soil scientist, Rod Venterea, found that the levels of nitrous oxide release were higher in areas not exposed to conventional tillage. Although it was noted that the difference wasn't huge, the results were significant because no-tillage land generally resulted in a lower crop yield.
"The point is you have to look at nitrous oxide emissions and yield together," said Venterea.
Venterea's team focused on measuring emissions based on crop yield over three seasons in Minnesota and found that under no-tillage crop management, nitrous oxide emissions were 50% to 66% higher.
The report's results clearly have implications for the ways in which greenhouse gases generated as a result of agriculture are monitored and analysed.
In the past, studies, such as those completed on the effect of fertilizer on greenhouse gas emissions, have concentrated on emissions per hectare. In future, it may be more insightful to focus on emission according to crop yield.
Venterea concluded that: "Expressing GHG emissions on a yield basis could reveal benefits to no-till management that otherwise might not be quantified."
Top Image Credit: Farmland after tillage ready to grow a crop © Andreas G. Karelias