Agricultural pollution refers to biotic and abiotic byproducts of farming practices that result in contamination or degradation of the environment and surrounding ecosystems, and/or cause injury to humans and their economic interests. The pollution may come from a variety of sources, ranging from point source water pollution to more diffuse, landscape-level causes, also known as non-point source pollution and air pollution. Once in the environment these pollutants can have both direct effects in surrounding ecosystems, i.e. killing local wildlife or contaminating drinking water, and downstream effects such as dead zones caused by agricultural runoff is concentrated in large water bodies.
Water pollution due to dairy farming in the Wairarapa area of New Zealand (photographed in 2003)
Aerial application of pesticide
Soil erosion: soil has washed from a ploughed field through this gate and into a watercourse beyond.
Centaurea solstitialis, an aggressively invasive weed, was probably introduced to North America in contaminated fodder seed. Agricultural practices such as tilling and livestock grazing aided in its rapid spread. It is toxic to horses, prevents native plants from growing (decreasing biodiversity and degrading natural ecosystems), and is a physical barrier to the migration of indigenous animals.
Agriculture encompasses crop and livestock production, aquaculture, fisheries, and forestry for food and non-food products. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people to live in cities. While humans started gathering grains at least 105,000 years ago, nascent farmers only began planting them around 11,500 years ago. Sheep, goats, pigs, and cattle were domesticated around 10,000 years ago. Plants were independently cultivated in at least 11 regions of the world. In the 20th century, industrial agriculture based on large-scale monocultures came to dominate agricultural output.
Winnowing grain in Ethiopia.
Centres of origin, as numbered by Nikolai Vavilov in the 1930s. Area 3 is no longer recognised as a centre of origin New Guinea (area P) was identified more recently.
Agricultural scenes of threshing, a grain store, harvesting with sickles, digging, tree-cutting and ploughing from ancient Egypt. Tomb of Nakht, 15th century BC
Agricultural calendar, c. 1470, from a manuscript of Pietro de Crescenzi