The atmosphere has an effect like a greenhouse on the earth’s temperature:
- Greenhouse gases (GHGs) trap some of the energy the earth releases to space
- GHGs have increased in the last 100 years
- The increase in GHGs is linked with global climate change--increasing climate variability and temperatures
- The major greenhouse gases are
- Water vapor
- Carbon dioxide (CO2)
- Methane (CH4)
- Holocarbons
- Nitrous oxide (N2O)
- GHGs differ in their ability to absorb the radiation leaving the Earth
- If the global warming potential of each gas is equated to carbon dioxide then methane is 21 times and nitrous oxide is 310 times more potent than one tonne of carbon dioxide over a 100 year period.
The predicted change in climate will affect crops and farming in general:
- Seeding dates
- Crop variety choices
- Pest and disease management
- Water management
- Weather extremes
Cropping practices result in GHG emissions
- CO2 is release mainly from decomposing organic matter and burning fossil fuel
- N2O is released mainly from nitrogen fertilizer and manure
Reducing CO2 emissions
- Soils can store (sequester) carbon in soil organic matter
- Practice reduced tillage, direct seeding and zero tillage
- Reduce fallow
Reducing N2O
- Match fertilizer needs to crop needs Apply nitrogen in the spring, close to or at seeding, especially if soils are often wet in the fall or early spring
- Balance fertilization to increase yields and use nutrients more efficiently
- Develop diverse crop rotations including legumes if possible
- Base manure applications on crop requirements.
