Food, Soil, and Pest Management - Environmental Science - page 220

Natural Capital Degradation

Food Production

Biodiversity Loss Soil Water Air Pollution Human Health

Loss and degradation
of habitat from
clearing grasslands
and forests and
draining wetlands

Erosion Water waste Greenhouse gas

emissions from
fossil fuel use

Nitrates in drinking
water

Loss of fertility Aquifer depletion

Pesticide residues
in drinking water,
food, and air

Salinization Increased runoff and flooding

from land cleared to grow
crops

Other air pollutants
from fossil fuel use

Fish kills from
pesticide runoff

Waterlogging

Greenhouse gas
emissions of nitrous
oxide from use of
inorganic fertilizers

Contamination of
drinking and
swimming water
with disease
organisms from
livestock wastes

Desertification Sediment pollution from erosion

Killing of wild
predators to protect
livestock

Fish kills from pesticide runoff

Surface and groundwater
pollution from pesticides and
fertilizers

Belching of the
greenhouse gas
methane into the
atmosphere by
cattle

Loss of genetic
diversity from
replacing thousands
of wild crop strains
with a few
monoculture strains

Bacterial
contamination of
meat Overfertilization of lakes and

slow-moving rivers from runoff
of nitrates and phosphates from
fertilizers, livestock wastes, and
food processing wastes

Pollution from
pesticide sprays

Figure 10-18 Natural capital degradation: major environmental effects of food production. According to UN
studies, land degradation reduced cumulative food production worldwide by 13% on cropland and 4% on
pastureland between 1950 and 2000.

by soil erosion, salt buildup, and chemical pollution,
and 17% has been seriously degraded. Such environ-
mental factors may limit food production in India and
China, the world's two most populous countries.

Traditional crossbreeding is a slow process, typi-
cally taking 15 years or more to produce a commer-
cially valuable new variety, and it can combine traits
only from species that are close to one another geneti-
cally. It also provides varieties that remain useful for
only 5-10 years before pests and diseases reduce their
effectiveness.
Today, scientists are creating a third green revolu-
tion —actually a gene revolution —by using genetic engi-
neering to develop genetically improved strains of
crops and livestock animals. This technology involves
splicing a gene from one species and transplanting it
into the DNA of another species (Figure 4-11, p. 75).
Compared to traditional crossbreeding, gene splicing
takes about half as long to develop a new crop, cuts
costs, and allows the insertion of genes from almost
any other organism into crop cells.
Ready or not, the world is entering the age of ge-
netic engineering. More than two-thirds of the food
products on U.S. supermarket shelves now contain
some form of genetically engineered crops, and the
proportion is increasing rapidly.

10-5 INCREASING FOOD
PRODUCTION

Science: Traditional Crossbreeding
and Genetic Engineering
We can increase crop yields by using crossbreeding to
mix the genes of similar types of organism and by
using genetic engineering to mix the genes of different
organisms.
For centuries, farmers and scientists have used cross-
breeding to develop genetically improved varieties of
crop strains. Such selective breeding has yielded
amazing results. Ancient ears of corn were about the
size of your little finger and wild tomatoes were once
the size of a grape.