Title: Agriculture - Wikibooks, open books for an open world
Headings: Agriculture
Agriculture
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Content: About 42% of the world's laborers are employed in agriculture, making it by far the most common occupation. Agriculture may often cause environmental problems because it changes natural environments and produces harmful byproducts. Some of the negative effects are: Surplus of nitrogen and phosphorus in rivers and lakes
Detrimental effects of herbicides, fungicides, insecticides, and other biocides
Conversion of natural ecosystems of all types into arable land
Consolidation of diverse biomass into a few species
Soil erosion
Depletion of minerals in the soil
Particulate matter, including ammonia and ammonium off-gasing from animal waste contributing to air pollution
Release of feral plants and animals
Odor from agricultural waste
Soil salination
Agriculture is cited as a significant adverse impact to biodiversity in many nations' Biodiversity Action Plans, due to reduction of forests and other habitats when new lands are converted to farming. Some critics also include agriculture as a cause of current global climate change. According to the United Nations, the livestock sector (primarily cattle, chickens, and pigs) emerges as one of the top two or three most significant contributors to our most serious environmental problems, at every scale from local to global. It is one of the largest sources of greenhouse gases - responsible for 18% of the world’s greenhouse gas emissions as measured in CO 2 equivalents. By comparison, all transportation emits 13.5% of the CO 2. It produces 65% of human-related nitrous oxide (which has 296 times the global warming potential of CO 2) and 37% of all human-induced methane (which is 23 times as warming as CO 2 ). Agricultural policy focuses on the goals and methods of agricultural production.