Solutions to Nutrient runoff
As agriculture is the major focus to reduce nutrient pollution in developed countries, solutions must account for decreasing nutrient pollution from animal manure as well as fertilizers. Developed nations must create a plan to reduce nutrient runoff using methods that cater to each region. The following methods can be used to reduce nutrient runoff.
- Animal Manure: Often, animals are given far more nutrients than their bodies can absorb, leaving the rest to be expelled out as manure. A study conducted by the USDA estimated that a dietary level of 0.31 percent phosphorus led to 42.4 kg/day of milk production in cows and 7g/ha of phosphorus dissolved in runoff (Sharpley, et al.). Meanwhile, a phosphorus level of 0.47 percent lead to only 39.4 kg/day of milk production and 79 g/ha of runoff (Sharpley, et al.). Clearly, it would be of economic benefit to reduce the amount of phosphorus in a cow's diet, which would also drastically decrease the amount of runoff, helping decrease biodiversity loss downstream. To further decrease phosphorus runoff, enzymes can be added to animal feed that encourages the animal's body to absorb phosphorus (Sharpley, et al.). Overall, however, measurements must be made to determine the amount of nutrients an animal actually needs in its diet (which will vary throughout the animal's life). Making these measurements can lead to both an economic benefit and decrease biodiveristy loss by decreasing runoff.
- Crop Fertilizers: In the millennium assessment, it was estimated that America alone applies 20-30 percent more fertilizer to crops than is necessary (Howarth, et al). This value can be reduced by making precise measurements of how much nitrogen and phosphorus is actually necessary to receive a maximum output from crops. However, even this reduction would not be enough to greatly reduce the size of America's dead zones, or other dead zones around the world that are caused by nutrient runoff (Sharpley, et al.). This nutrient runoff collects in coastal areas and creates algae blooms, which then deplete the oxygen in the water, killing other organisms in the area. Industrial countries like the United States must adopt an integrated strategy in order to reduce fertilizer runoff.
- Planting perennial crops instead of annual ones in highly sensitive areas, for instance, would retain nitrogen in the soil and greatly reduce the loss of groundwater. In fields in Iowa, for instance, those planted with alfalfa instead of corn or soybeans lost 30- to 50-fold less nitrates (Howarth, et al.). A country's ability to implement this strategy, however, would depend on that country's demand for perennial crops or on its ability to export them.
- Another strategy to retain nitrogen in the ground is to plant winter cover crops. This technique would reduce the rate of nitrates leaching into the ground, which generally occurs in the winter and spring due to heavier rainfall in those seasons (Howarth, et al.). This strategy can provide an economic benefit as well: planting winter crops can lead to a 30 USD gross profit for every acre of land (Mannering, 2007). This value ignores the added benefit of nitrogen fixation provided by the winter crop.
- Many sources suggest that fertilizer must be applied at the right time to maximize its ability to remain in the soil. The Millennium Ecosystem Assessment found that farmers generally apply fertilizer in the fall when they have more time to do so, even though it is really needed in the spring and summer. Fall application of fertilizer was estimated to increase leaching by 30-40 percent (Howarth, et al.).
- Phosphorus runoff must also be reduced, although it is important to note that phosphorus tends to have an effect on the immediate ecosystem and its effects do not spread nearly as far as nitrogen. Therefore, phosphorus will be of more concern to freshwater ecosystems than to marine ecosystems. Methods to reduce phosphorus runoff include tillage and planting along contours (this will have little effect on reducing nitrogen loss) (Howarth, et al.) as well as creating buffer zones in runoff-sensitive areas. These buffer zones should be both near the point source to prevent nutrient runoff into freshwater aquatic systems, and they should include the wetlands by the oceans. Current wetlands must be preserved to maximize their ecosystem services, but constructed wetlands can also be created to "soak up" all types of nutrient runoff. According to one study, the removal rates of constructed wetlands varied between 20 and 57 percent (Zhen, 2011). The cost of a constructed wetland can vary between 35,000 and 150,000 USD per acre (Argonne National Laboratory). Note that these costs represent capital costs of creating the actual wetland: maintenance costs are extremely low (Argonne National Laboratory). Furthermore, this cost is about 50 percent less than the costs of traditional runoff treatment facilities.
- Governmental Policy: Policies must be implemented on the regional level, as not all parts of a country are equally sensitive to agricultural runoff (Marine Biodiversity: An Economic Valuation, 2006). A country may set a goal of reducing nutrient runoff by 10 percent, for instance, but much of the effort put into meeting this goal will result in inefficiency if runoff hotspots are not identified. The above methods of reducing agricultural runoff must be tailored to meet regional ecosystem and human requirements. In order to reduce agricultural runoff, it would be most effective to set clear national goals and standards, but then devote the resources to collect data and test various regions' sensitivity to agricultural runoff. Efforts to reduce runoff can then be focused on areas that are in the most need. It is also important to note that costs of implementing nutrient management plans will vary from region to region. An example of these differences can be seen in the USDA's Comprehensive Nutrient Management plan, which amounted to a total cost of 17.4 billion USD over a 10-year period (United States Department of Agriculture, 2003). This plan focused on nutrient pollution management as it related to livestock, and did not include pollution caused by growing crops for human consumption. It included costs of record keeping, manure and wastewater storage, land treatment, feed nutrient management, technical assistance, and off-export of nutrients(United States Department of Agriculture, 2003). The plan's costs of implementation in each region varied: for instance, implementing such a plan in the west coast resulted in an average cost of 19,000 USD per farming operation, whereas in the Northern plains the cost was just over 5,000 USD (United States Department of Agriculture, 2003).
Many developing nations that have a great amount of biodiversity are also areas of concern or already have developed dead zones (National Geographic, Dead Zone). As sewage and industrial pollution are the main sources of nutrient runoff in developing countries, solutions to reduce nutrient runoff here will have a different focus. However, there are developing countries that experience nutrient pollution due to agricultural runoff, just as developed countries also have problems with industrial pollution and sewage. Plans to reduce runoff must be tailored by the nation to meet its needs and provide the most effective solution to reduce nutrient runoff.
- Community Control: Controlling this form of pollution requires both a national and community effort. Information must be made accessible to the people so that they are aware of the pollution that comes from factories and industrial plants in their vicinity. In general, a more educated public that is aware of pollution problems and a more visible factory increases the price of pollution, which results in companies taking the effort to implement green technologies to reduce their pollution (Pargal, 1995).
- Governmental Policy: The effect that the community has on indirectly controlling pollution depends on governmental policy, even if the public is well educated about the problems of pollution. The governments legal and social structure must be conducive to allowing the public to influence such matters. Furthermore, laws must be clear to prevent loopholes and give specific responsibilities to the people as well as clear regulations to the companies (Blackman). Regulations must be created to meet the needs of various regions, as in some areas pollution has a greater effect on biodiversity, or biodiversity is more concentrated in these areas of a given country.
- Economic Methods: In Colombia, a pay-as-you-pollute plan has been put into action to replace the command and control method that is commonly relied on (Blackman). A country that uses the command and control method would implement a set of laws that would then be enforced through legal methods. The pay as you pollute method, on the other hand, uses economic incentives. This method proved to be effective in reducing pollution in lakes and rivers, as companies had to pay for each unit of pollution. To make such a plan effective, however, the government must devote resources to collect data on nutrient runoff and fees from the companies. These responsibilities can be delegated to local governments, but must also then be kept up with by the national government itself.
On a local level, the most successful sewage cleanups occur when sewage is simply diverted from an infected lake (How Bad is Eutrophication at Present?). However, these results can be misleading if the sewage is simply dumped further downstream. In North America, 10 percent of sewage is dumped into the ocean untreated, while in Asia this number is closer to 65 percent, and in Africa most sewage is not treated at all (Howarth, et al.). Currently, even most "clean sewage" is not treated for nutrient removal. In both developed and developing countries, infrastructure must be built and maintained to effectively clean sewage. Technology already exists that can remove up to 95 percent of phosphorus and up to 90 percent of nitrogen from sewage (Howarth, et al.). The Millennium Ecosystem Report estimates that such technologies would increase the cost of treating pollution by 25 percent, representing a deterrent for increased sewage control. (Howarth, et al.). This value includes both capital and operational costs. The cost of implementing this new technology can be reduced if the sewage treatment plant is built to treat sewage for nitrogen and phosphorus from the start. This can easily be done in developing countries where the infrastructure is yet to be built (Howarth, et al.). Proper sewage treatment would not only benefit biodiversity directly but also benefit human health, making it useful for nations to build such infrastructure. Furthermore, current sewage plants can be adjusted and new ones built in areas first with a high population density. This would enable the government to spread the cost of the new technology over a large amount of people, making such a plan economically easier to implement. In the United States, for instance, tertiary water treatment plants cost residents as low as 18 USD a month without subsidies and as high as 49 USD per person per month (Ragsdale, 2007). While these rates were deemed affordable in various American municipalities, more research will be needed to decrease the costs for many populations in developing nations. Focusing on high-density regions will also have the biggest impact on biodiversity, as a significant source of nutrient pollution would be reduced.
- Works Cited
- Beaumont, N., Townsend, M., Mangi, S., & Austen, M., C. (2006). Marine biodiversity: An economic evaluation. Report. Plymouth: Plymouth Marine Laboratory.
- Blackman, A. Alternative pollution control policies in developing countries (Issue Brief) Resources For the Future.
- Blackman, A. Economic incentives to control water pollution in developing countries. Retrieved 11/09, 2011, from: http://www.rff.org/focus_areas/features/Pages/Water-Pollution-Developing_Countries.aspx
- Dead zone. National Geographic
- Executive summary costs associated with development and implementation of comprehensive nutrient management plans. (2003). United States Department of Agriculture.
- How bad is eutrophication at present? Retrieved 11/09, 2011, from http://www.unep.or.jp/ietc/publications/short_series/lakereservoirs-3/2.asp>
- Howarth, R., & Ramakrishna, K. Nutrient management (Report: Millennium Assessment).
- Mannering, J. V., Griffith D.R., & Johnson K.D. (2007). Winter cover crops- their value and management (Report: Purdue University). Retrieved from http://www.agry.purdue.edu/ext/forages/publications/ay247.htm
- Pargal, S., & Wheeler, D. (1995). Informal regulation of industrial pollution in developing countries evidence from Indonesia. The World Bank.
- Peconic river remedial alternatives wetlands Restoration/Constructed wetlands. Argonne National Laboratory. Retrieved from http://www.bnl.gov/erd/peconic/factsheet/wetlands.pdf
- Ragsdale, D. (2007). Advanced wastewater treatment to achieve low concentration of phosphorus (Report: Environmental Protection Agency).
- Sharpley, A. N., Sims, D., Lemunyon, J., Stevens, R., & Parry, R. Agricultural phosphorus and eutrophication second edition (Issue Brief: USDA.)
- Strayer, D., L., & Dudgeon, D. (2010). Freshwater biodiversity conservation: Recent progress and future challenges. The North America Benthological Society.
- Worm, B., Barbier, E. B., Beaumont, N., Duffy, J. E., & Folke, C. (2006). Impacts of biodiversity loss on ocean ecosystem services. Science, (314), 787-790.
- Zhen, W. B., et al. (2011). Removal efficiency and balance of nitrogen in a recirculating aquaculture system integrated with constructed wetlands. Journal of Environmental Science & Health, Part A: Toxic/Hazardous Substances & Environmental Engineering, GreenFile (46.7), 789-794.