Agriculture has long been recognized as an important
source of non-point or diffuse water pollution. Key
problems include:
• Sediment runoff – this can cause siltation problems and
increase flood risk;
• Nutrient runoff – nitrogen and phosphorus are key pollutants
found in agricultural runoff, they are applied to
farmland in several ways, including as fertilizer, animal
manure and municipal wastewater, and can result in eutrophication
in receiving waters;
• Microbial runoff – from livestock or use of excreta as fertilizer
(domestic animals, such as poultry, cattle, sheep
and pigs, generate 85% of the world’s animal faecal
waste – Dufour et al., 2012);
• Chemical runoff from pesticides, herbicides and other
agrichemicals can result in contamination of surface and
groundwater; in addition residues of veterinary drugs
may also cause water pollution.