March 1, 2013
The San Joaquin Valley, located in central California, represents a vital portion of the United States’ domestic agriculture. The main source of water in the San Joaquin Valley is the northern flowing San Joaquin River, which collects its water from the Sierra Nevada snow melt. Irrigation of this river began in the early 19th century but was limited by lack of technology. Starting in the 1920’s farmers began to pump groundwater, which immensely increased the amount of irrigated farmland in the area. Today in the San Joaquin Valley there are 230 different types of crops grown annually which represent 25% of the United States food supply.
While the San Joaquin Valley signifies such a vast portion of our nations food supply it also represents only 1% of farmland in the country. We rely heavily on this source of food, but it is at risk of being lost due to desertification of the area. Desertification occurs due to urbanization, overgrazing, soil salinization, land subsidence, and unsustainable agricultural practices. For example, 95% of the country’s raisins are produced in the San Joaquin Valley. In order to get from grapes to raisins farmers burn grape trays to dry the grapes.
The two most dire problems that agriculture in the San Joaquin Valley face are risks of land degradation due to subsidence and salinization. Subsidence began in the 1920’s along with groundwater pumping. Between 1925 and 1977 the land sunk 30 feet. Due to the combination of mass cultivation of the land and the over pumping of ground water, a clay layer that once resided deep below the farmland is now just below the surface. This clay layer, now just below the crops, prevents water from percolating into the ground and recharging the secluded aquifer that lies beneath. Not only is this aquifer now greatly depleted, but it reduces the amount of available water for irrigation of the overlying farmland.
Another issue threatening this region is salinization of the soil. While some salt in water is good and even beneficial, too much salt can be toxic to plants and humans. Some salt naturally exists in irrigated waters due to dissolved minerals from the land and the cycle of evaporation, which leaves salts behind taking only water. Another way salt gets into water is from farmer’s fertilizers. When crops are irrigated the plants only consume the water, leaving the salt behind in the soil, similar to evaporation. The levels of salt in this soil and its surrounding waterways are constantly increasing because of a positive feedback loop. Salinization of the soil makes it extremely difficult for plants to grow and also physically degrades the land, drying it out. Beyond this a large portion of the salts found in the soil of the San Joaquin Valley are removed trough runoff into the San Joaquin River.
This issue of Salinization creates another slew of environmental risks including increased salinization of fresh water systems and the ocean. The San Joaquin Valley is home to several cities ranked in the top 25 worst air polluted cities. This is mainly due to the high level of particulate matter found in the air resulting from desertification of the land. The current solution to this issue of salinization is to treat the runoff water in a desalinization plant. However this solution is energy intensive, costly and further contributes to the already polluted air.
It is clear that the San Joaquin Valley is an essential source of food to the United States and that this resource is at great risk of depletion. Alternative solutions include planting salt tolerant crops, improving the drainage of the area and using sustainable farming practices. With the population of the United States growing at an ever increasing rate it is imperative we do something to remedy these issues in order to sustain this vast source of food that is so vital to the sustainability of our society.
By: Olivia Trombadore & Matt Binder
Peer Reviewed Articles
Gerrit Schoups, et al. “Sustainability of Irrigated Agriculture in the San Joaquin Valley, California.” Proceedings of the National Academy of Sciences of the United States of America 102.43 (2005): 15352-6. Print.
Mount, Jeffrey; & Twiss, Robert. (2005). Subsidence, sea level rise, and seismicity in the Sacramento-San Joaquin Delta. San Francisco Estuary and Watershed Science, 3(1). <http://escholarship.org/uc/item/4k44725p>
Bittman, Mark. “Heavenly Earth.” The New York Times. The New York Times, 14 Oct. 2012. Web. 19 Feb. 2013. <http://www.nytimes.com/2012/10/14/magazine/californias-central-valley-land-of-a-billion-vegetables.html?pagewanted=all>.
“California’s San Joaquin Valley Produces Agriculture and Air Pollution.” Care 2 Make a Difference. 12 Aug. 2011. Web. 19 Feb. 2013. <http://www.care2.com/causes/californias-san-joaquin-valley-produces-agriculture-and-air-pollution.html>.
“Indicators in the Study Sites.” Desire.Web. 19 Feb. 2013. <http://www.desire-his.eu/en/assessment-with-indicators/wp21-identifying-indicators-thematicmenu-173/56-indicators-in-the-study-sites>.
“San Joaquin (soil).” Wikipedia. Wikimedia Foundation, 02 Feb. 2013. Web. 19 Feb. 2013. <http://en.wikipedia.org/wiki/San_Joaquin_(soil)>.
United States. Environmental Protection Agency. Central Valley Regional Water Control Board. Salinity in the Central Valley. May 2006. Web. 19 Feb. 2013. <http://www.waterboards.ca.gov/centralvalley/water_issues/salinity/centralvalley_salinity_alternatives_archives/initial_development/swrcb_02may06_ovrvw_rpt.pdf>.
September 19, 2011
The Central Valley of California is a fertile bed of over 350 diverse species of agricultural crops, some of the major cash crops being rice, grapes, cotton, and almonds. California’s agricultural industry makes up 15% of the entire nation’s crops and made a profit of $37 billion in the year 2009.
Despite these numbers, desertification is an increasingly major problem.
Between 1998 and 2000, 10,000 acres of farmland were lost every year in Central Valley from urbanization alone—this doesn’t account for the acres of fertile farmland lost due to overgrazing, climate change, or poor farming practices. Currently, California is losing 178 km2 of arable, fertile land each year. Southern California especially, being a very arid and drought-inclined region to begin with, has a problem with increasing salinity and compound minerals in the soil, caused by overdrawing ground water (United States Geological Survey).
Desertification is not only the result of human activity. The UN Convention to Combat Desertification identifies the other major cause of desertification to be climatic variations—for example, erosion, drought and irregular rainfall, and violent winds. Essentially it renders the soil infertile, not only for planting and agriculture but for any organic life. Desertification occurs on a global scale, particularly through deforestation and drought. Areas around the Amazons, for example, have undergone desertification because the trees are being harvested for wood and cleared for farmland, and much of the space lies fallow. Similarly, in California, trees are cleared using the “slash and burn” method to open fields for cheap soybean and livestock cultivation.
Desertification is a challenge for California because it is a desert environment supporting an increasingly large population on limited water imports. The situation becomes more dire when the effects of global warming are considered, which dramatically expedite desertification. Owens Valley, California, for example, became a desert when all of the natural water resources were diverted to Southern California for drinking water and crop irrigation. The San Joaquin Valley is a region that has undergone natural desertification due to climate change, a result of surface crusting, salinization and waterlogging problems.
Most popularly considered solutions to desertification involve addressing problems of drought. Every 5 years in California a new Drought Contingency Plan (DCP) is released. In 2008, the last DCP, tactics included aggressive conservation, new groundwater and surface water storage facilities, and environmental restoration. GMOs also offer the possibility of growing crops that are resistant to drought, thus using less of the precious water resources to yield the same or greater amount of agriculture.
Similarly, Air-to-Water harvesters are a new technology that essentially takes the humidity in the air and convert it to usable water. This can slow desertification significantly.
From a more bottom-up perspective, education and conservation initiatives will also drastically reduce the human contribution to desertification. Programs teaching grey-water usage, water conservation, and the transformation of lawns into food forests can save a lot of water if it is implemented locally and broadly. Natural forests and wetlands need to be protected rather than cleared, farmed, and abandoned.
While desertification is in and of itself a natural process, the human factors can and must be reduced, especially in California, if we are to live harmoniously with the land and reap the benefits of its yield.
About the authors: Xueyou Wang and Kayla Duarte are undergraduate students in the USC Dana and David Dornsife College of Letters, Arts and Sciences.