Greenhouse gases (GHGs), including carbon dioxide (CO2 ), methane (CH4 ) and nitrous oxide (N2 O), absorb radiation from the sun, and trap heat in the atmosphere, acting like a greenhouse or a layer of insulation for Earth. GHGs are parts of the earth’s natural processes, but human activities over the last few centuries have increased GHG levels far past where they should be. This change has very negative consequences for our climate, including increasing global temperatures, and more frequent episodes of severe weather. Carbon dioxide is produced by farm equipment. It’s also released when soil is disturbed, or when plants decay. Methane from cattle is part of a natural carbon cycle. Released into the air through belches, methane goes into the atmosphere for a period of approximately 12 years until it breaks down. During
photosynthesis, plants capture this carbon and store it until an animal grazer comes along, digesting it and releasing the carbon as methane for the cycle to continue. It can also come from livestock manure, food waste and grasses. Nitrous oxide primarily comes from fertilizer. When plants can’t use all the nutrients that they’re given, the excess fertilizer can be lost into the air through de-nitrification as nitrous oxide, a greenhouse gas estimated to be 300 times more potent than carbon dioxide.
Overall, GHG emissions from Canadian agriculture have stayed about the same for the last 20 years76, even though the quantity of food production has increased dramatically. That outcome is mostly because farms have become more efficient — they’re able to grow and raise more food while using less land, water, and fuel. This change also reflects the increased carbon sequestration in cropland.
4R Nutrient Stewardship is a program that’s been developed to let the world know when food has been grown sustainably. It balances farmer, industry, and government goals to improve crop productivity and fertilizer efficiency, while also benefiting the environment. How? Through the “4Rs” — Right Source @ Right Rate, Right Time, Right Place®: putting the right type of fertilizer, at the right amount, in the right spot, at the right time for it to be most effective. It’s already been in use in Canada for the last 15 years, making Canadian farmers already among the most sustainable growers in the world. The 4Rs principle is one of many best management practices that can help agriculture to reduce its greenhouse gas emissions from fertilizer use even further.
Did you know...
That microbes found in the soil can help cereal crops like corn or wheat to create their own nitrogen fertilizer? They can naturally convert nitrogen from the atmosphere into a form that these crops can use as nutrition. This aspect is called biological nitrogen.