Greenhouse gases are necessary for maintaining a warm, stable climate and supporting life on earth. But when concentrations become too high, more solar radiation is trapped and the climate can change.
- Increased temperatures
- More powerful and frequent storms
- Greater periods of extended drought and rainfall
- Intrusion of new pests and weeds
The Culprit: Greenhouse gases
Carbon is stored in soil organic matter but is released as carbon dioxide (CO2) when intensive tillage increases soil organic matter decomposition rate and carbon loss. Because organic crop production often uses a lot of tillage to reduce weeds, alternative methods of weed control are being researched.
Carbon dioxide is the most prevalent greenhouse gas but two other gases have a greater potential to warm the environment.
Methane is 20 times more effective at warming the environment than CO2 and nitrous oxide is 300 times more effective. Agriculture is the main source of nitrous oxide emissions in the U.S., due in large part to nitrogen based fertilizers, including manure and compost. Crop residue breakdown also contributes to nitrous oxide emission.
Carbon dioxide levels reflect soil organic content in the soil. Soil organic matter is very important for crop productivity and soil sustainability.
Nitrous oxide levels reflect nitrogen content in the soil. Nitrogen is one of the most important nutrients for crop growth.
By minimizing our contribution to climate change, we are preserving a more stable environment for forming for succeeding generations. For more information see the following article:http://cafnrnews.com/2011/11/gases-and-grasses/.
Monitoring greenhouse gas emission from soil
To monitor gases given off from soil, an anchor with a lip is placed in the soil and removed only when tillage is done. We use a restaurant steam table tray with the bottom cut out for an anchor. A lid is then placed on the anchor and sealed with clamps. The lid has a septum in it that allows for gas removal via a syringe. Gas samples are taken at 0, 30 and 60 minutes after the lid is clamped to the anchor. Samples are analyzed in a gas chromatograph.