Cropland nutrient management
When synthetic fertilizers are applied to croplands, excess nitrogen is released to the atmosphere or carried away by water. That nitrogen is emitted into the air in the form of nitrous oxide, a greenhouse gas 300 times more potent than carbon. Proper nutrient management ensures that the amount of nitrogen applied to the field does not exceed the amount that the plants can absorb. Nutrient management also ensures fertilizer application is timed to avoid unnecessary runoff and reapplication.
Realizing the potential for cropland nutrient management will require farmers to apply best practices in nutrient management across nearly the whole global cropland area of 1.4 billion hectares.
Managing nutrients in croplands could prevent the release of up to 635 million metric tons of carbon dioxide equivalent per year (MtCO2e/year). That’s comparable to the emissions from 134 million passenger vehicles per year.
The primary challenge to improving nutrient management will be disseminating information to farmers and effectively encouraging them to implement best practices. That may be particularly challenging where new methods might require more planning and monitoring than the business-as-usual approach.
In some regions, there are existing policies, originally designed to stimulate agricultural production, that actively subsidize the overuse of fertilizer. In such cases, policy changes will be necessary to reduce fertilizer use.
To maximize the potential for this pathway, the world’s farmers would need to adopt the standard of nutrient management practiced in North American and Western European agriculture.
While the scale of this pathway is large, improving nutrient management is a very low-cost intervention that can be implemented immediately. More efficient use of fertilizer can reduce a farmer’s costs without reducing productivity. A large improvement could be realized simply by disseminating information about best practices among regions such as East Asia, where fertilizer use is unnecessarily high.
In the future, further improvements could come from precision agriculture technologies and alternative forms of fertilizer.
Spotlight: Lake Erie’s 4R Nutrient Stewardship Certification Program
In recent years, harmful algal blooms in Lake Erie have hurt tourism and fishing and led to rising water treatment costs. Now, agricultural retailers and farmers in Indiana, Michigan and Ohio are coming together to improve the long-term quality of Lake Erie’s waters through the 4R Nutrient Stewardship Certification Program.
The program encourages farmers to adopt so-called “4R” practices: using the Right Source of Nutrients at the Right Rate and Right Time in the Right Place.
The program offers a science-based approach for plant nutrition management and sustained crop production, while considering specific individual farms’ needs. As of 2015 the program had engaged 5,500 farmers to implement these practices to over 1.1 million hectares across Indiana, Michigan and Ohio, reducing runoff into Lake Erie and likely preventing the release of hundreds of thousands of metric tons of CO2e/year.
Similar improvements in nutrient management will be especially critical in regions such as East Asia, where fertilizer is currently applied at far higher rates than is necessary to maintain yields