April 22, 2012
Can California agriculture help increase carbon sequestration?
The carbon cycle is currently out of balance. Humans have introduced too much carbon dioxide to the atmosphere from burning fossil fuels, causing climate change and changing weather patterns. We have the technology to do work with nature to sequester more carbon. Agricultural land accounts for 455 million acres of the total land area in the US of 1.9 billion acres. Unfortunately, since the time that we have settled the land, the soil organic content has dropped to about less than one-fourth of what it once was.
Humans could sequester organic carbon into soil if we operated farms and ranches with practices that increase and maintain the organic material in the soil. For example, conventional farm practices that include improper tillage and overuse of chemical fertilizers result in about 20,000 pounds of carbon dioxide. We can help control the CO2 released by adding organic material to the soil. Practices in which soil is mulched and rarely tilled result in a dramatic decrease in the loss of carbon dioxide from the soil. Tilling the soil upsets soil life and exposes it to sunlight and oxidation, releasing large amounts of CO2. In the natural environment, the carbon-based roots and other soil life are rarely exposed or destroyed. Such oxidation naturally takes place, but the natural process is much slower, so plants can capture the CO2 and reprocess it instead of letting it into the atmosphere.
California is a huge venue for carbon storage potential, as much of California’s agriculture is perennial. Perennial crop residue is more readily decomposed than annual residues, and perennials store carbon within the woody biomass of trees and vines. Further, with the increase in agricultural yields, the biomass returned to the soils has increased, promoting sequestration. Rice farmers have also contributed to sequestration efforts. Instead of burning the fields after harvest, most of the crop residue is now returned to the soil. Through similar small efforts, California agriculture can greatly increase its agricultural carbon sequestration.
Although there has not been significant research into vineyards as carbon sequestration resources, they hold high potential. Permanent cover cropping has been shown to increase soil organic matter when used instead of bare fallow rotations. Growing cover crops, however, can be negatively impacted by one light tillage annually. Further research is needed to understand the ability of different cover crops to increase soil carbon in vineyards. Still, there have not been many studies of vineyards and carbon sequestration. Vineyard specific studies are needed to understand the effects of vineyard management practices on carbon storage.
California could almost double carbon sequestration by adapting conservation tillage practices and returning prunings to the soil. This assumes that area for perennial agriculture continues to expand, and that the biomass of crops continues to grow. As of 2002, California’s agriculture was not sequestering through conservation tillage although the practice is commonly cited as sequestering carbon by reducing soil respiration. Due to the low erosion potential of the land and the high intensity multicropping, California agriculture has not widely adopted conservation tillage. If further research were done on adapting conservation tillage to California agriculture, we could help restore balance to the carbon cycle.
Sources:
http://www.greenhq.net/carbon-cycle/
http://www.jstor.org.libproxy.usc.edu/stable/40061767
http://www.sustainablewinegrowing.org/docs/CSWA%20GHG%20Report_Final.pdf
Christopher Miranda is an undergraduate in the USC Dana and David Dornsife College of Letters, Arts and Sciences.
October 30, 2011
Overuse and Abuse of Nitrogen Fertilizers in California Agricultural Lands
Without the use of nitrogen fertilizer, California agricultural lands could risk not reaching its optimum yield. As a consequence, food production companies would lose a certain amount of profit and consumer demands could possibly not be reached. Often times as nitrogen passes through plants and soil in a repetitive cycle the loss of nitrogen is greater than the benefit and as a result, the plant growth is no longer as significant. This ultimately puts a limit on crop production rate. However, scientists have come up with farming techniques that have revolutionized agriculture. Nitrogen fertilizer is one of those inventions and is a product of the Haber-Bosch process. This fertilizer has ‘allowed agricultural production to keep pace with world population growth,’ according to the International Fertilizer Industry Association.
Nitrogen fertilizers have many effects on the Nitrogen cycle that can lead to negative anthropogenic effects as well as environmental. There are several disruptions in the natural cycle of Nitrogen that can occur.
First of all, artificial nutrients dumped into soil can result in a loss of its capacity to hold nutrients (Lowe, pg.10). It is estimated that plants have no use for up to 50% of the chemical fertilizers placed on them.
Agricultural regions of the Southwest are composed of mainly shallow, coarse-textured and therefore highly permeable soils and aquifers. It is common for these areas to be vulnerable to nitrate contamination (Harter pg.3).
Nitrates are the most readily formed and available use of Nitrogen, and they are extremely soluble. It is easily carried through the soil with water to be taken up by plants. If the land is irrigated, there is a chance nitrate can move past the plant roots and into the groundwater or other agricultural tile drainage or surface waters (Mosier, pg.13). In major agricultural areas such as the Imperial, Central, Salinas, and other coastal valleys in California, there is groundwater nitrate contamination (Harter pg.3). When nitrate levels exceed those of the EPA’s Maximum Containment level set at 10mg/l, certain health risks occur. One of these being methemoglobinemia (infants especially are vulnerable).
In addition, when converting ammonium into nitrate, nitrite will naturally occur. Nitrite is similar to nitrate in its movement through the soil and possibility of contaminating groundwater (Reid para.7).
Ammonia volatilization also contributes to nitrogen losses. Ammonia volatilization occurs in areas where the soil is warm, dry, and too much of a nitrogen fertilizer is applied (Buchholz). There is a concern with concentrations becoming toxic. This can happen when too many of these tiny particulates enter a confined area. Ultimately, one of the biggest concerns is reducing air quality (Reid, pg. 11).
Moreover, the effects that Ammonia and nitrate can have on biodiversity can be disastrous. Eutrophication that can lead to algal blooms and a die-off of fish species are a concern from Nitrogen fertilizer use such as ammonia emissions that can deposit on bodies of water and nitrate leached from the soil (Mosier pg.17). Ultimately, the impacts this is having can decrease fish populations resulting in less available resources for people to consume.
Lastly, the process of denitrification can transform the nitrogen fertilizer into nitrous oxide. This is a greenhouse gas, which has approximately three hundred times more impact than carbon dioxide on climate change (Lowe, pg.10). The effects of using these nitrogen fertilizers may not be shown right away as can be seen from eutrophication, but the long-term impacts may be detrimental.
If California continues with overusing and abusing its Nitrogen fertilizer use, it makes itself susceptible to the outcomes seen in China’s croplands. The soil became more acidic so that it was unproductive, and in addition to water contamination, China experienced increases in greenhouse gas emissions. All of these disastrous consequences were negligent monitoring of nitrogen fertilizers.
China’s overuse of nitrogen fertilizers has forced the government to take action against the pollution. One of their solutions is a five-year plan, which calls for a reduction in carbon intensity by implementing new domestic laws that legally require companies to meet emission reduction targets.
Although California may not have a government plan to target the nitrogen pollution, there are other ways in which farmers, themselves can become proactive in reducing the pollution. Some example solutions include securing stored manure in order to prevent runoff or enforcing livestock feed rations that are not above the necessary.
Another solution is to completely phase out chemical fertilizers and instead use organic fertilizers. According to the Third World Network’s report, “Avoiding Nitrogen fertilizer over-use is a “multiple win”: farmers save money, there is less water pollution, smaller greenhouse gas emissions, and a smaller acidification burden on soil and water.”
Image Source:
Harter, Thomas. “Agricultural Impacts on Groundwater Nitrate.” Nitrates in Groundwater. University of California, Davis, July-Aug. 2009. Web. 10 Oct. 2011. <http://www.swhydro.arizona.edu/archive/V8_N4/feature2.pdf>.
Citations:
Mosier, Arvin, John K. Syers, and J. R. Freney. Agriculture and the Nitrogen Cycle: Assessing the Impacts of Fertilizer Use on Food Production and the Environment. Washington, D.C.: Island, 2004. Print.
Lowe, Marcy, and Gary Gereffi. “A Value Chain Analysis of Selected California Crops.” Center on Globalization. Duke University, 04 July 2008. Web. 10 Oct. 2011. <http://www.cggc.duke.edu/environment/valuechainanalysis/CGGC_CACropsReport_7-4-08.pdf>.
Reid, Keith, Kevin McMcKague, and Hugh Simpson. “Environmental Impacts of Nitrogen Use in Agriculture.” Ontario Ministry of Agriculture, Food and Rural Affairs / Ministère De L’Agriculture, De L’Alimentation Et Des Affaires Rurales. Web. 10 Oct. 2011. <http://www.omafra.gov.on.ca/english/engineer/facts/05-073.htm>.
Harter, Thomas. “Agricultural Impacts on Groundwater Nitrate.” Nitrates in Groundwater. University of California, Davis, July-Aug. 2009. Web. 10 Oct. 2011. <http://www.swhydro.arizona.edu/archive/V8_N4/feature2.pdf>.
Buchholz, Killpack. “WQ257 Nitrogen in the Environment: Ammonia Volatilization | University of Missouri Extension.” University of Missouri Extension Home. Department of Agronomy. Web. 10 Oct. 2011. <http://extension.missouri.edu/p/WQ257>.
About the authors: Ticia Lee and Wendy Whitcombe are working towards their bachelor degrees in the USC Environmental Studies Program.
September 19, 2011
California Soon to Suffer the Environmental Costs and Impacts of Desertification
It is believed California is currently undergoing desertification. The long-term impacts and environmental costs associated with this process will take a devastating toll on the environmental future of the state. According to an article from Remote Sensing by Doris Lam, Tarmo Remmel and Taly Drezner, the present conditions of the majority of California’s lands are arid and semi-arid, which makes California highly susceptible to climate changes and anthropogenic impacts leading to desertification.
There are a combination of factors that when placed together can have the potential for disaster. During the 1930′s in Oklahoma, the combination of drought, arid climate, and land misuse led to the dust bowl resulting in depression, a mass exodus of people, poverty, hunger, high economic costs, loss of biodiversity, and unusable land for agriculture. Currently, because of California’s arid climate, land erosion and misuse, and rising global temperatures, the potential for disastrous environmental impacts is on a greater scale and drawing near.
U.S. Secretary of Energy, Steven Chu, projects the future of California’s agricultural lands to decline. According to the climate reports Chu has reviewed, global temperatures are only expected to reach staggering heights. Along with these increases in temperatures come major environmental impacts such as shortages in water supplies and loss of agricultural land. Without a secure water supply, agricultural processing and more importantly food production, could be in danger. In an article from Nature Geoscience, Diana Wall warns that the lack of water will cause great damage to the essential functions of healthy soil, which include providing proper environments for crop growth with various nutrients and other levels of biodiversity.
The rise in temperatures will also affect levels of precipitation and perhaps even cause valuable lands to lose their ability to sustain abundant crops for California’s growing population. A twenty-five percent drop in precipitation levels beginning in 2007 and lasting through 2009 is an example of this situation. The consequence of this occurrence was that the stream flows were forty percent below normal standards.
As a result, farmers pumped groundwater as a short-term answer to their water problems. However, in the long run, the groundwater resources were depleted greatly and a valuable resource was used unsustainably. A total reduction in groundwater during the drought proved to be 48 times worse than reductions in a comparable period earlier in the decade. A continuation of similar events in using water resources unsustainably will eventually force the water-deprived grounds of California to move quickly towards desertification.
The state of California’s economy relies heavily on its agriculture. A report from the 2010-2011 edition of the California Agricultural Resource Directory states that in 2009, California agricultural exports reached 12.4 billion, which was a 66 percent increase over a length of seven years. A sudden plummet to California’s agricultural productions due to the presence of desertification would result in not only a decrease in harvested crop acreage but also in jobs for Californian residents.
California’s success in farming over the years has earned the state the title of “the agricultural powerhouse of the United States.” The state’s economy is heavily dependent on the profits of their agricultural productions. The environmental impacts and costs of desertification in California will have a huge toll on millions of people. Not only will it do damage to the state’s economy but it will also cause a great increase in unemployment rates. Moreover, the total cost of attempts toward restoring the deteriorated agricultural lands will most likely continue to rise since the chances of restoring those lands to its native standards are close to impossible. The desertification of California agricultural lands will be detrimental to the entire population of the state.
About the authors: Ticia Lee and Wendy Whitcombe are working towards their bachelor’s degrees in Environmental Studies in the USC Dana and David Dornsife College of Letters, Arts and Sciences.