Monday, March 21, 2016

New Green Challenge:  How to Grow More Food on Less Land

Tomatoes at a farmers' market in Wisconsin. (Credit: Patrick Kuhl/Flickr) Click to Enlarge.
For researchers trying to figure how to feed a world of 10 billion people later in this century, the great objective over the past decade has been to achieve what they call “sustainable intensification.”  It’s an awkward term, not least because of conventional agricultural intensification’s notorious record of wasting water, overusing fertilizers and pesticides, and polluting habitats.  But the ambition this time is different, proponents say:  to figure out almost overnight how to grow the most food on the least land and with the minimal environmental impact. The alternative, they say, is to continue plowing under what’s left of the natural world.  Or face food shortages and political unrest. 

Up to now, the tendency in talking about sustainable intensification has been to focus on the supply side and on exciting technological innovations of one sort or another, from gene editing to satellite monitoring.  In his new book Half-Earth, even E. O. Wilson invokes the idea, not too hopefully, that “a new Green Revolution can be engineered” to spare the half of the world he argues should be set aside for nature. 

But achieving consensus about what sustainable intensification should mean — or whether it’s the right objective in the first place — has proved complicated and increasingly contentious. “Depending on how one defines it,” one researcher commented, “I’m in favor of it, or against it.” 

To critics, the engineering focus has tended to put intensification ahead of sustainability, making it just a re-boot of the original Green Revolution.  Technological solutions appeal to large farms in the industrial world, which can afford to invest in them.  They say the technological fixes also distract from more challenging social reforms like slowing the rate of population growth, shifting away from crops like corn ethanol that don’t put food on the table, or ending subsidies for livestock production, which currently eats up an appalling 75 percent of the world’s agricultural land. Technological solutions also appeal most directly to large farms in the industrial world, which can afford to invest in them.  But the population growth and the clearing of land for agriculture are mainly happening in the developing world. 

Fertilizer is a key topic of discussion everywhere — most obviously because sustainable intensification means curbing overuse in the industrial world.  The European Union began regulating fertilizer use 25 years ago, to reduce farm runoff that was polluting groundwater and turning water bodies hypoxic.  The EU’s Nitrates Directive led to a 30 percent reduction in fertilizer use, even as yields were increasing substantially. 

That kind of intensification — more production with fewer impacts — is certainly also possible in the United States.  University of Minnesota ecologist G. David Tilman cited, by way of example, multiple studies showing that farmers could get the same yield with substantially less fertilizer, if they were willing to time applications more precisely to the needs of the crop.  The pressure to cut fertilizer use is especially urgent in the Mississippi River Valley, where agricultural runoff has created the world’s second largest ocean “dead zone” in the Gulf of Mexico. 

So far, state and federal agencies have relied on voluntary efforts to reduce runoff, with little success.  But the switch from old- to new-style intensification could start to become mandatory, depending on the outcome of a new lawsuit by the City of Des Moines charging upstream Iowa farm counties with polluting its drinking water and imposing huge filtration costs on city residents. 

Read more at New Green Challenge:  How to Grow More Food on Less Land

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