It has been widely accepted that agriculture is the unique largest user of surface and groundwater supplies, which consumes a global average of 70% of water resources. However, agriculture can definitely causes water pollution through inappropriate use and dispose of pesticide, livestock pollution and poor water resource management.
It cannot be denied that pesticide that has been diffusely applied in agriculture contributes a lot to the advancement of georgic output and development of the quantity of agricultural produce. However, it is said that some of improper activities in using and stocking pesticide, which are probably caused by lack of training of users in pesticide handling and application, such as using pesticide for killing trash fish, using old pesticide drums for drinking water and dumping surplus pesticide mixtures into water courses following application, had lead to some environmental and public health hazards such as ecosystem dysfunction, loss of biodiversity, contamination of groundwater resources and so called “water-borne diseases”.
On the other hand, water pollution is also attribute to Stockbreeding – a branch of agriculture. An article report by the Natural Resources Defense Council, July 2001, pointed out “In 1995, an eight-acre hog-waste lagoon in North Carolina burst, spilling 25 million gallons of manure into the New River. The spill killed about 10 million fish and closed 364,000 acres of coastal wetlands to shell fishing.” Moreover, According to the U.S. Environmental Protection Agency, more than 27,000 miles of rivers and contaminated groundwater, in dozens of states, has polluted with livestock waste. Last by not the least, nutrients in animal waste can obviously cause algal blooms, which contribute to “dead zones” in the coastal waters by using up oxygen in the water. These “dead zones” cannot contain enough oxygen to support aquatic life.
Although great improvement has been made in technology after the middle of 20th century, poor water resource management, mainly irrational irrigation, still exists in many countries. This, probably result from inadequate water quality data, can definitely exert the worst impacts on water quality. For instants, many countries can no longer manage pollution by dilution, leading to higher levels of aquatic pollution.
It is undoubted that some measures should be carried out to modify the funds of pesticide usage, reduce livestock pollution and improve water resource management. Firstly, farmers and commercial sprayers must hold application certificates that include education in pesticide issues; secondly, individual farmers should be required to maintain records of pesticide application; thirdly, a certain organization should be found to continuously supervise the use of pesticide that dose by the farmer and reduces excessive application; fourthly, to avoid over-fertilization, the rate of nitrogen fertilizer to be applied needs to be calculated on the basis of the “crop nitrogen balance”; Fifthly, keep the soil covered with vegetation, which can build-up of soluble nitrogen by absorbing mineralized nitrogen and preventing leaching during periods of rain. Sixthly, Optimize cultivation techniques such as weed, pest and disease control, liming, balanced mineral fertilizers should be introduced as soon as possible; Seventhly, rational irrigation, namely, precision irrigation, one of the least polluting practices as well as reducing net cost of supplied water, should be taken into practice in the sooner future.
It is clear that, through out the entire development of human being, agriculture played a significant role. At the same time, environmental problems were brought to our attention one by one, during the progress of agriculture. Consequently, series of measures should be bound with the activities of pesticide usage and live stocking. Furthermore, complement of water resource management should always keep up with the advancement of agriculture. Otherwise, the cost of developing agriculture will outweigh the benefit by a long way.