“Sustainable” has become one of the buzzwords of the 21st century. Increasing numbers of universities offer courses or even programs in “sustainability,” and many large companies boast substantial departments devoted to the subject. In April, many of the iconic multinational companies in the agriculture/food sector were represented at a three-day “Sustainable Product Expo,” convened by Wal-Mart — the largest retailer in the US — at its Arkansas headquarters.
However, as with many vague, feel-good concepts, “sustainability” contains more than a little sophistry. For example, sustainability in agriculture is often linked to organic farming, whose advocates tout it as a “sustainable” way to feed the planet’s rapidly expanding population. But what does “sustainable” really mean, and how does it relate to organic methods of food production?
The organic movement’s claims about the sustainability of its methods are dubious. For example, a recent study found that the potential for groundwater contamination can be dramatically reduced if fertilizers are distributed through the irrigation system according to plant demand during the growing season; organic farming, however, depends on compost, the release of which is not matched to plant demand. Moreover, though composting receives good press as a “green” practice, it generates a significant amount of greenhouse gases (and is often a source of pathogenic bacteria in crops).
The study also found that “intensive organic agriculture relying on solid organic matter, such as composted manure that is mixed in to the soil prior to planting, resulted in significant down-leaching of nitrate” into groundwater. Increasing the nitrate levels in groundwater is hardly a hallmark of sustainability, especially with many of the world’s most fertile farming regions in the throes of drought.
A fundamental reason that organic food production is far less “sustainable” than many forms of conventional farming is that organic farms, though possibly well adapted for certain local environments on a small scale, produce far less food per unit of land and water. The low yields of organic agriculture — typically 20 to 50 percent below conventional agriculture — impose various stresses on farmland, especially on water consumption.
A British meta-analysis published in 2012 identified some of the stresses that were higher in organic agriculture. For example, it found that “ammonia emissions, nitrogen leaching, and nitrous oxide emissions per product unit were higher from organic systems,” as were “land use, eutrophication potential, and acidification potential per product unit.”
Lower crop yields in organic farming are largely inevitable, owing to the arbitrary rejection of various advanced methods and technologies. Organic practices afford limited pesticide options, create difficulties in meeting peak fertilizer demand and rule out access to genetically engineered varieties. If organic production were scaled up significantly, the lower yields would lead to greater pressure to convert land to agricultural use and produce more animals for manure, to say nothing of the tighter squeeze on water supplies — all of which are challenges to sustainability.
Another limitation of organic production is that it works against the best approach to enhancing soil quality — namely, the minimization of soil disturbance (such as that caused by plowing or tilling), combined with the use of cover crops. Such farming systems have many environmental advantages, particularly with respect to limiting erosion and the runoff of fertilizers and pesticides. Organic growers do frequently plant cover crops, but in the absence of effective herbicides, they often rely on tillage (or even labor-intensive hand weeding) for weed control.