USC Dana and David Dornsife College of Letters, Arts & Sciences

Agriculture is one of the largest and most important industries in California, supplying half of all the produce for the nation. According to the California Department of Food and Agriculture, agriculture generates almost $100 billion for the state’s economy. The strength of the agricultural industry was built on the diversity of crops from almonds and broccoli to grapes and squash that can be grown in the mild climate and fertile soil available in California.

The nitrogen cycle is key to making sure that crops continue to grow so that the agricultural industry can maintain the same level of crop yields and keep on feeding the country. Nitrogen is used by plants not only in nucleic acids and proteins, but also specifically with chlorophyll, which is key to photosynthesis, the process that provides plants with food to continue growing. However, plants cannot access atmospheric nitrogen in the form of N₂—the nitrogen gas needs to be converted or fixed into a different form that is accessible to plants.

Therefore, the current problem that farms are facing is that not enough nitrogen is being naturally fixed to promote plant growth and fulfill the demand for produce. Farms in California are beginning to rely more and more heavily on nitrogen fertilizers to boost plant productivity. However, this input of manufactured nitrogen has many effects on the nitrogen cycle. Many plants do not absorb all of the nitrogen from the fertilizer, leaving excess nitrogen in the soil, which causes an imbalance to the ecosystem. This nitrogen can also be deposited in bodies of water through runoff, causing eutrophication due to its role as a limiting nutrient. As agriculture in California has risen to be major industry, more synthetic fertilizers are being used to grow crops, and the excess nitrogen is becoming an important problem.

Fortunately, this issue has been recognized by organizations like the Environmental Protection Agency and the California Department of Food and Agriculture. In 2010, the Agricultural Sustainability Institute at UC Davis sponsored the California Nitrogen Assessment, an attempt to assess California’s current agricultural needs in regards to nitrogen and to discuss possible solutions. In the information and progress report, they stated, “Our researchers are working to establish a baseline of credible knowledge about nitrogen, which includes comprehensive accounting of nitrogen flows, agricultural practices, and the policies that shape these practices. They will also assess the quality of information and knowledge about these issues.”

Some solutions to be considered are utilizing a crop-rotation system with nitrogen-fixing crops, or developing crops that use endosymbiotic nitrogen-fixing bacteria to reduce the amount of synthetic, nitrogen-rich fertilizers used. Another option would be genetically modifying crops to be more nitrogen efficient, but there are many controversies surrounding such practices.

In terms of recent developments, the CDFA posted a press release stating “The California State Board of Food and Agriculture will discuss a variety of topics related to the nitrogen cycle and the proactive work by California farmers and ranchers on the issue at its upcoming meeting on March 6th [2012] in Sacramento.” While they have yet to release a summary of the meeting, the conference shows that there is still state interest in regulating the nitrogen cycle in regards to agriculture. As the agriculture industry continues to grow, it is important to be aware of the nitrogen cycle and the impact humans have on it.

Sources:

http://asi.ucdavis.edu/newsroom/blog/nitrogen-in-california-agriculture-the-big-uncertainties

http://www.cdfa.ca.gov/egov/press_releases/Press_Release.asp?PRnum=12-005

http://www.cdfa.ca.gov/is/ffldrs/production_guide.html

http://www.cdfa.ca.gov/state_board/

http://asi.ucdavis.edu/research/nitrogen/documents/NitrogenAssessmentMidtermUpdate2010.pdf

http://www.economywatch.com/agriculture/american/california.html

http://www.cdfa.ca.gov/CDFA-History.html

Harriet Arnold and Divya Rao are undergraduates in the USC Dornsife College of Letters, Arts and Sciences.