Reducing Greenhouse Gas Emissions from Cultivated Fields May Require New Strategies

Researchers at the Agricultural Research Service's North Central Soil Conservation Research Laboratory in Morris, Minn., are exploring practical ways to keep carbon in the soil and reduce greenhouse gas emissions. Soil scientist Jane Johnson conducted a study to investigate the impact of crop rotation, tillage, and fertilizer on emissions. The study found that reducing nitrogen fertilizer and changing crop rotation cycles may not be enough to curb greenhouse gas emissions. Other factors, such as tillage systems and soil warming during spring thaws, may also play a significant role.

Key Takeaways:

• The study found that greenhouse gas releases were largely the same under two-year and four-year rotation systems.
• Applying nitrogen fertilizer had less overall impact than anticipated on nitrous oxide emissions.
• Nitrous oxide emissions peaked during spring thaws, regardless of which tillage or rotation system was used.
• Chisel and moldboard plowing increased carbon dioxide emissions for a short time, but measured over the course of a year, there was no difference between plots with intensive tillage and plots without it.
• Methane releases showed no consistent patterns.
• The study highlights the importance of considering tillage systems, soil warming, and other factors in reducing greenhouse gas emissions.

Statistics:

• The study compared two-year and four-year crop rotation systems.
• The experiment included plots with and without fertilizer, as well as different tillage systems.
• The study used a hydraulic soil probe to measure organic carbon sequestered in the soil.
• The study measured emissions of carbon dioxide, methane, and nitrous oxide.
• The research is part of a five-year project, GRACEnet, with over 32 sites examining strategies to reduce agriculture's climate change footprint.

Sources:

• U.S. Department of Agriculture, Agricultural Research Service (ARS), Dennis O'Brien, Curbing Greenhouse Gas Emissions from Culivated Fields.
• Jane Johnson, Soil Scientist, ARS North Central Soil Conservation Research Laboratory, Morris, Minn.
• Agricultural Research magazine, November/December 2009 issue.