A survey conducted by the US Environmental Protection Agency (EPA) has concluded that the water quality of rivers, streams and lakes in the United States is rapidly deteriorating. It laid most of the blame for this situation on the overuse of agricultural chemicals, especially fertilisers.
The same can be said of the water quality in a great many other countries, including Thailand.
The dangers of agricultural pesticides and herbicides are well known, and according to the EPA, 12 of the most popular pesticides in the United States have ingredients known to cause cancer. The overuse of fertilisers draws less attention, but the dangers should not be discounted. While there is no doubt that adding essential nutrients to farmland can have beneficial effects on crop yields, farmers everywhere seem to believe that more is better, despite a mountain of evidence to the contrary. A point of diminishing returns is rapidly reached and yields are actually often reduced if fields are overfertilised. Meanwhile, the excess chemicals that are not taken up by plants end up polluting waterways and the air.
The EPA report, which was described as the first statistically based overview of the condition of US rivers and streams, said that 55% of the watercourses of US rivers and streams were in poor condition for aquatic life, largely because of agricultural run-off contaminated by fertilisers with high levels of phosphorus and nitrogen. The report indicated a marked decline in water quality in recent years and also cited run-off from urban areas, shrinking ground cover and pollution from mercury and bacteria as reasons for the decline.
A similarly comprehensive study has not been done on the quality of surface water in Thailand, but a 2008 report titled "Use of agrochemicals in Thailand and its consequences for the environment" finds a similar decline in water quality corresponding to a large extent with the overuse of fertilisers. The report, issued by Greenpeace Research Laboratories at the UK's University of Exeter, was assisted by researchers at the Asian Institute of Technology in Bangkok as well as the department of environmental and water resources engineering at Northeastern University in Boston.
The report says: "The use of chemical fertilisers in Thailand started to increase exponentially in the 1970s; between 1961 and 2004 fertiliser use increased more than 100 times, a spectacular increase from 18 thousand tonnes in 1961 to 2 million tonnes in 2004. But in spite of this massive increase in chemical fertiliser use, the yield of rice and maize increased barely one time, doubling in 45 years. This indicates a tremendous loss of fertilisers into the environment due to their unbalanced use and poor management."
Surveys cited in the report found that in some agricultural areas in the Central Plains, 55% of the groundwater wells tested had nitrate levels above the World Health Organisation's drinking water safety limit, and 46% of wells tested in Nakhon Pathom province had high levels of nitrates.
Studies around the globe indicate that often up to 95% of applied fertiliser is not used by the crop and thus ends up as an environmental pollutant. Scientists believe lymphoma, bladder and digestive tract cancer, diabetes and some birth defects and miscarriages may be linked to high nitrate levels, and that children may be particularly susceptible. It also causes eutrophication _ explosive growth bursts of algae that deplete oxygen for fish and other organisms _ in local bodies of water and in coastal waters.
Ironically, even as the quality of rivers, streams and lakes around the world deteriorates, a report released not long ago by Unicef and the WHO says that the world has met the Millennium Development Goal (MDG) target of halving the proportion of people without access to safe drinking water, well in advance of the MDG 2015 deadline. Between 1990 and 2010, says the report, over 2 billion people gained access to improved drinking water sources, such as piped-in supplies and protected wells.
This is a wonderful accomplishment and great news, particularly for people who are generally among the most marginalised members of their respective societies. But unfortunately other organisms, especially aquatic life, are suffering because of the overall decline in water quality. And if water quality continues to decline in general, how much longer, and at what price, will we have access to good drinking water?
Chemical fertilisers have been shown to be a major contributor to the problem and the use of effective natural alternatives should be encouraged. At the same time, farmers need to be educated as to how much chemical fertiliser they should be using.