Healthy soil and sustainable growing

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Why Planting Farms in Skyscrapers Won't Solve Our Food Problems
'Vertical' farming would not solve the most pressing agricultural problems -- 
just make things worse.
May 3, 2010  |
http://www.alternet.org/food/146686/why_planting_farms_in_skyscrapers_won%27t_solve_our_food_problems?page=entire

Agriculture in America has become an ecological, social and nutritional 
disaster of sufficiently huge scale to inspire a frenzy of book-writing, 
filmmaking, conference-holding and project-initiating in recent years. The 
critiques that emerge are often right on the money, highlighting pesticide 
and nitrate pollution, soil erosion, the consequences of meat production in 
feedlots and confinement sheds, the destruction of rural communities and the 
poor nutritional quality of food. But the solutions being proposed have not, 
for the most part, been of the same scale as the problems; most would do 
little more than nibble at the edges of America's long-running agricultural 
fiasco.

A striking example of such ill fit between problem and proposed response can 
be found in the November 2009 issue of Scientific American, where Dickson 
Despommier, a professor of public health and environmental health sciences at 
Columbia University, made his case for what he calls "vertical farms," a 
vision he promotes through his site verticalfarm.com.

After doing a very good job of describing the terrible toll that agriculture 
takes on soil, water, and biodiversity across the globe, Despommier's article 
lays out a proposal to replace soil-based farming with a system of producing 
food crops in tall urban buildings-to, he writes, "grow crops indoors, under 
rigorously controlled conditions, in vertical farms. Plants grown in 
high-rise buildings erected on now vacant city lots and in large, multistory 
rooftop greenhouses could produce food year-round using significantly less 
water, producing little waste, with less risk of infectious diseases, and no 
need for fossil-fueled machinery or trans¬port from distant rural farms."

Despommier describes how one of his scenarios-which are based on the use of 
hydroponic or "aeroponic" methods of growing plants without soil-might work: 
"Let us say that each floor of a vertical farm offers four growing seasons, 
double the plant density, and two layers per floor-a multiplying factor of 16 
(4 _ 2 _ 2). A 30-story building covering one city block could therefore 
produce 2,400 acres of food (30 stories _ 5 acres _ 16) a year." By 
extrapolating numbers like those and assuming extraordinary leaps in 
technology, as well as the repeal of Murphy's Law, he has made such a 
convincing case for vertical farms that, he claims, "many developers, 
investors, mayors and city planners have become advocates." Time magazine has 
run a generally positive story on the concept. And an Australian architect is 
currently planning to build the first full-scale vertical farm, in China.

The idea for vertical agriculture grows out of the realization that there are 
not enough exposed horizontal surfaces available in most urban areas to 
produce the quantities of food needed to feed urban populations. Although the 
concept has provided opportunities for architecture students and others to 
create innovative, sometimes beautiful building designs, it holds little 
practical potential for providing food. Even if vertical farming were 
feasible on a large scale, it would not solve the most pressing agricultural 
problems; rather, it would push the dependence of food production on 
industrial inputs to even greater heights. It would ensure that dependence by 
depriving crops not only of soil but also of the most plentiful and 
ecologically benign energy source of all: sunlight.

Groping in the dark

Agriculture as it has always been practiced-call it "horizontal 
farming"-casts an extremely broad, green "net" across the landscape to 
capture solar energy, which plants use in producing food. Photosynthesis 
converts a small percentage of the solar energy that falls on a leaf into the 
chemical energy in food. But that small percentage is enough; sunlight is 
plentiful, and left to themselves, plants do not have to rely on any other 
sources of energy to grow and produce.

Nevertheless, modern agriculture has managed to make food production an 
energy-losing proposition. Its emphasis on increasing yield per unit of land 
and per unit of human labor has meant a sharp increase in the input of fossil 
energy-with farms often using more energy to produce the food than is 
contained in the food. Some of the most notorious features of factory farming 
are dark, dank hog and poultry confinement operations; now, Despommier's plan 
would create plant-confinement operations as well.

Most of the attention that vertical farming has received in the media has 
been embedded in the context of rooftop gardens, greenhouses, and "green" 
high-rise facades (pdf). But those methods for growing modest amounts of 
relatively expensive food (usually vegetables) differ from Despommier's plan 
to "farm" the interiors of buildings in one important respect: they are at 
least capable of capturing solar energy efficiently.

For obvious reasons, no one has ever proposed stacking solar photovoltaic 
panels one above the other. For the same reasons, crop fields cannot be 
layered one above the other without providing a substitute for the sunlight 
that has been cut off. Even with all-glass walls, the amount of light 
reaching plants on all but the top story of a high-rise would fall far, far 
short of what is needed. (On a sunny day, a room with plenty of windows may 
look well-lit to our eyes' wide-open pupils, but that light intensity is a 
tiny fraction of what is needed for crop production.) A significant portion 
of the light hitting the building would be turned back by the glass, and 
direct sunlight would penetrate into the interior of a vertical farm only 
when the sun is low in the sky (especially if, as Despommier recommends, two 
layers of plants are stuffed into each story.) Even then, it would reach the 
crop plants at a low angle, so that each square inch of leaf would receive 
much less light than if the light were hitting the leaf from above.

As a result, the lion's share of a vertical farm's lighting would have to be 
supplied artificially, consuming resource-intensive electricity rather than 
free sunlight. This led us to wonder, "What would be the consequences of a 
vertical-farming effort large enough to allow us to remove from the 
landscape, say, the United States' 53 million acres of wheat?" That's not an 
unreasonable question. In fact, it follows from Despommier's own reasons for 
promoting the practice. He argues, correctly, that soil is currently being 
abused on a massive scale; therefore, to address the problem, vertical 
farming would need to displace agriculture from a large proportion of the 
currently cropped landscape.

Our calculations, based on the efficiency of converting sunlight to plant 
matter, show that just to meet a year's U.S. wheat production with vertical 
farming would, for lighting alone, require eight times as much electricity as 
all U.S. utilities generate in an entire year [see calculations here]. And 
even if it were energetically possible, growing the national wheat crop under 
lights could substitute for only about 15 percent of US cropland. Were it to 
succeed, that energy buildup of unprecedented scale would still leave 85 
percent of cropland in place.

Despommier suggests using renewable sources to supply the power needed for 
vertical farming but fails to consider the scale-up that would be required. 
Wind, solar, biomass, geothermal, and other renewable electricity sources 
combined account for about 2% of U.S. generation. So to grow the national 
wheat crop vertically using renewable sources would mean scaling up the 
nation's renewable sector by 400-fold just to run the lights! (His proposals 
for doubling plant density, using round-the-clock light, or pushing 
year-round production, even if they could be made to work, would increase 
production per unit of area but would not decrease the energy needed for 
lighting per unit of food produced.)

One of our colleagues suggested, with his tongue in cheek, an alternative: 
"What about vertical nuclear energy? We could stack reactors in skyscrapers 
alongside the farming skyscrapers, to provide the electricity!" Fortunately, 
no one's going to try that, because just to grow our wheat. we'd have to add 
another 4000 or so nuclear reactors to the hundred or so currently in the 
United States.

To have a much greater impact on soil conservation efforts than the 
displacement of wheat would accomplish, we'd want to take indoors the 
nation's number-one grain, corn, which occupies about a quarter of our 
cropped acreage, and some of the most badly abused land. But corn makes 
wheat's electricity consumption look modest. Because wheat naturally grows 
mostly in fall, winter, and spring and produces lower yields than summer 
crops like corn, its light requirement is lower. The U.S. corn crop would 
require energy for lighting equivalent to 40 times the current US electricity 
supply.

Maybe trying to satisfy the nation's huge grain requirements with vertical 
farming is too ambitious. Assume instead that we were to take a more modest 
approach and grow the national crop of vegetables under lights. If that 
required a similar level of lighting per unit area to that used for wheat, we 
would "only" have to double our national electricity generation. But removing 
all vegetable production from the landscape would preserve no more than 2 
percent of our currently cropped soils.

A question of control

Based on its energy requirements for lighting alone, vertical farming would 
be incapable of substituting for a substantial share of our soil-based 
agricultural production. But the lighting problem is only the first among 
many obstacles facing high-rise agriculture. Climate control to achieve 
suitable growing conditions would add huge energy requirements. And light 
fixtures would release more energy as heat than as light, which in summer 
would put huge loads on air-conditioning systems. To maintain the good health 
of plants grown indoors, humidity and air circulation must be very precisely 
controlled, often at a high energy cost. And before any of those needs would 
come the gargantuan resource requirements for construction of the towers 
themselves.

Then there would be the impracticalities and energy requirements for 
producing and hauling artificial growth media, fertilizers, water, and other 
resources hundreds of feet up and getting harvests out of the towers. 
Pesticides could not be eliminated and would undoubtedly be applied in many 
situations. If Despommier has ever worked in a greenhouse, he knows that some 
of the pathogens and insects that damage crops in the field can be excluded, 
but that many others will flourish. Powdery mildew, aphids, mites, or other 
pests can easily wipe out greenhouse-grown wheat plants, for example, if 
chemical control is not used.

The system inevitably would also require an enormous input of manual labor. 
As a hydroponic model, Despommier points approvingly to 300-plus acres of 
greenhouses near Willcox and Snowflake, Arizona, in which EuroFresh Farms 
grows vegetables. Energetically, EuroFresh has no relevance to vertical 
farming, because it is a horizontal operation that makes good use of Arizona 
sunshine. But with four employees per cropped acre, it does provide a good 
example of the large manual labor requirements of a massive, intensive 
hydroponic operation.

EuroFresh's geographical location is no accident. It lies close to the 
nation's southern border, and the company employs large numbers of immigrant 
workers. It also employs inmates from a nearby branch of Arizona State 
Prison. If EuroFresh is to provide an encouraging example for vertical 
farming, other questions come to mind. Who will own and control the 
agricultural high-rises? How and from where will the stoop-labor force for 
vertical farming be recruited? What will become of the farm families whose 
central role in the nation's life has been replaced by vertical-farming 
operations? Will they find themselves migrating to the cities to tend 
corporate tomato vines?

The EuroFresh greenhouses can also illustrate some of the pitfalls of 
high-input indoor farming. In April, 2009, the company filed for chapter 11 
bankruptcy, having fallen victim, according to the Arizona Daily Star, to 
"its debt burden, labor troubles and crop pest problems," which included 
invasions of white flies. (EuroFresh emerged from bankruptcy in November.)

Alternatives

The solution to soil and water degradation is not to strip food-producing 
plants from the landscape only to grow them, deprived of sunlight, in 
vertical factory farms. Instead, we have to address the Achilles heel of 
agriculture itself: that it has displaced, on a massive scale, diverse stands 
of natural perennial vegetation (such as prairies, savannahs, and forests) 
with monocultures of ephemeral, weakly rooted, soil-damaging annual crops 
such as corn, soybean, and wheat. So far, the weaknesses of the current 
food-production system have been compensated for agronomically through 
greater and greater inputs of fossil fuels and other resources, worsening the 
ecological impact; vertical farming would extend that trend.

The landscape can be saved only through what we might call "three-dimensional 
farming," a system that is arranged horizontally across the landscape to 
capture and use sunlight but also puts down, deep, long-lived roots to 
protect the soil, manage water, nutrients efficiently, and help restore the 
below-ground ecosystems that agriculture has destroyed. That will require 
converting cropland to the production of diverse, food-producing, perennial 
crops. It will mean a reliance on natural processes and cohesive rural 
communities, not technological fantasies.
Stan Cox and David Van Tassel are plant-breeding researchers at The Land 
Institute in Salina, Kansas. Cox's book Losing our Cool: Uncomfortable Truths 
about Our Air-Conditioned World, will be published in June by The New Press. 
This article appeared in the Spring 2010 issue of Synthesis/Regeneration.