Though organic advocates tout their approach as best for the planet, a new study suggests that intensive conventional agricultural can help stave off the extinction crisis.
Some 1,800 species of plants and animals depend on native vegetation for survival, according to extensive field data collected from five continents. Agriculture’s impacts on wildlife could be greatly reduced if yields on existing farmland are optimized so as to spare remaining natural habitats from cultivation, researchers found.
And high-yield, intensive agriculture seems to be the most effective way to do that, even when some of its most significant environmental impacts are factored in.
The article, published in Nature, considered such trade-offs as the amount of land required for production under various methods, greenhouse gas emissions and other factors in comparing environmental costs and yields. “This study was conceived as an exploration of whether high-yield systems—central to the idea of sparing land for nature in the face of enormous human demand for farm products—typically impose greater negative externalities than alternative approaches,” the authors state.
The research is important because agriculture currently covers about 40 percent of the ice- and desert-free land on Earth, and accounts for about two-thirds of freshwater withdrawals. Meanwhile, the demand for food continually increases in response to the world’s growing population.
“[Agriculture’s] immense scale means that it is already the largest source of threat to other species, so how we cope with very marked increases in demand for food products will have profound consequences for the future of global biodiversity,” the authors state. “On the demand side, cutting food waste and excessive consumption of animal products is essential. In terms of supply, farming at high yields (production per unit area) has considerable potential to restrict humanity’s impacts on biodiversity.”
Though high-yield farming can lead to other problems, such as greenhouse gas and ammonia emissions, soil depletion and pesticide use, “such metrics underestimate the overall impacts of lower-yield systems,” the authors note. “To be robust, assessments of externalities also need to include the off-site effects of management practices, such as crop production for supplementary feeding of livestock, or off-farm grazing for manure inputs to organic systems.”
To more accurately compare systems, researchers developed a framework that “involves plotting the environmental costs of producing a given quantity of a commodity against one another, across alternative production systems,” the paper states. Their findings suggest that “per unit production, land-efficient systems often produce lower externalities.”
The researchers collated data for applying this framework to five major externalities — greenhouse gas emissions, water use, nitrogen, phosphorus and social losses — in four major agricultural sectors: Asian paddy rice, European wheat, Latin American beef and European dairy.
In dairy, for example, organic methods require twice the land of conventional systems, which also had substantially lower greenhouse gas emission costs. In general, the researchers found: “To generate the same quantity of agricultural product, low-yield systems require more land, allowing less to be retained or restored as natural habitat. This is in turn likely to increase GHG emissions and soil loss and alter hydrology—although we could find only enough data to explore the first of these effects.”
The researchers found that useable data is “worryingly limited”— and nearly nonexistent for important food crops like African cassava. They also warned that “pursuing promising high-yield systems is clearly not the same as encouraging business-as-usual industrial agriculture. Some high-yield practices we did not examine, such as the heavy use of pesticides in much tropical fruit cultivation, are likely to increase externality costs per unit production. Of the high-yield practices we did investigate some, such as applying fossil-fuel-derived ammonium nitrate to UK wheat, impose disproportionately high environmental costs.”
They also noted: “If promising high-yield strategies are to help solve rather than exacerbate society’s challenges, yield increases instead need to be combined with far-reaching demand-side interventions and directly linked with effective measures to constrain agricultural expansion.”
The authors suggested that “our framework can serve as a device for identifying existing yield-enhancing systems that also lower other environmental costs—and perhaps more importantly, for benchmarking the environmental performance of promising new technologies and practices.”