Page 268 - Environment: The Science Behind the Stories

sustainable agriculture is agriculture that does not deplete estimates that as more developing nations go through the demo-
soils faster than they form (p. 234). It is farming and ranching graphic transition (pp. 219–220) and become wealthier, total
that does not reduce the amount of healthy soil, clean water, meat consumption will nearly double again by the year 2050.
and genetic diversity essential to long-term crop and livestock
production. Simply put, sustainable agriculture is agriculture Our food choices are also energy choices
that can be practiced in the same way in the same place far
into the future. What we choose to eat has ramifications for how we use energy
No-till farming and other soil conservation methods and the land that supports agriculture. Every time that one
(Chapter 9) are primary avenues to help make our agriculture organism consumes another, only about 10% of the energy
more sustainable. Reducing fossil-fuel inputs and the pollution moves from one trophic level up to the next, while the great
these inputs cause is a key goal of sustainable agriculture. majority of energy is used up in cellular respiration (p. 50). For
As a result, many approaches essentially move away from the example, if we feed grain to a cow and then eat beef from the
industrial model and toward more traditional models, such as cow, we lose most of the grain’s energy to the cow’s metabo-
the cultivation of diverse landraces of Mexican maize. Yet plenty lism. Energy is used up as the cow converts the grain to tissue as
of analysts today feel that technology offers our best hope of it grows, and as the cow conducts cellular respiration on a daily
making agriculture sustainable, and that the genetic engineering basis to maintain itself. For this reason, eating meat is far less
of crops and livestock is a vital component of this effort. In this energy-efficient than relying on a vegetarian diet, and it leaves a
chapter we will survey how our food is produced, the impacts far greater ecological footprint.
our agriculture exerts, and the many alternative pathways that In contrast, if we eat lower on the food chain (a more veg-
may help move us toward sustainability in agriculture. etarian diet), we put a greater proportion of the sun’s energy to
use as food. The lower on the food chain we eat, the smaller is
our ecological footprint, and the more of us Earth can support.
Some animals convert grain feed into milk, eggs, or meat
Raising Animals for Food more efficiently than others (Figure 10.9). Scientists have cal-
culated relative energy-conversion efficiencies for different
Food from cropland agriculture makes up the majority of the
human diet, but most of us also eat animal products. As our Feed Produce output
population has grown, consuming animal products has come input (edible weight)
to have significant environmental, social, agricultural, and
economic impacts. How we respond to demand for animal
products will have a major effect on the quest for sustainable Beef
agriculture and on our society’s ecological footprint.
20.0 kg 1 kg
Consumption of animal products is growing

As wealth and global commerce have increased, so has human-
ity’s consumption of meat, milk, eggs, and other animal
products (Figure 10.8). The world population of domesti-
cated animals raised for food rose from 7.3 billion animals to Pork
27.5 billion animals between 1961 and 2011. Most of these ani-
mals are chickens. Global meat production has increased five- 7.3 kg 1 kg
fold since 1950, and per capita meat consumption has doubled.
The United Nations Food and Agriculture Organization (FAO) CHAPTER 10 • A g R i C ulT u RE , Bi o TECH nology, A nd THE Fu T u RE o F Food

Eggs
Per-person global production (kg/person/year) 30 Seafood 2.8 kg 1 kg Chicken
4.5 kg
1 kg
40
Meat

20

10 1.1 kg 1 kg Milk
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

Year Figure 10.9 Producing different animal food products
requires different amounts of animal feed. Twenty kilograms
Figure 10.8 Per-person production of meat from farmed of feed must be provided to cattle to produce 1 kg of beef. Data
animals and of seafood has risen steadily worldwide. Data from Smil, V., 2001. Feeding the world: A challenge for the twenty-first century.
from U.N. Food and Agriculture Organization (FAO). Cambridge, MA: MIT Press. 267

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