Environmental effects

Agriculture (which we have defined as croplands and pasture) occupies approximately 38 per cent of the earth’s terrestrial surface with much of the remaining surface unsuited for agrarian practices (Foley et al., 2011). As the single largest land use on the earth, the environmental effects of agriculture are widespread and impact not only the site where production of food and fiber occurs but also offsite areas. What crops are produced, where they are produced and how the crops are produced define the potential environmental impacts. Environmental effects impacted by agricultural systems can be characterized broadly as changes to biodiversity and alterations in the ecological services upon which humans depend. Collectively, the negative environmental impacts attributable to unsustainable practices of agriculture are well documented (Gordon et al., 2010). Cultivation of the soil for planting and for weed management may cause soil erosion onsite and may degrade habitat, air and water resources on and offsite. Use of chemicals to minimize yield losses from weeds and other pest complexes may affect non-target organisms, including desirable ones like pollinators and pest predators that provide benefits to agriculture and humans in general. Concomitant with increasing crop yields, fertilizer use in some regions of the world has dramatically altered global nitrogen and phosphorous cycles and impacted water quality, aquatic ecosystems and marine fisheries (Millennium Ecosystem Assessment, 2005).