Page 235 - Environment: The Science Behind the Stories

underground container full of carbon-rich wood chips) to filter Conservation measures like these are saving the
out excess nitrogen so it does not pollute groundwater. Nielsens—and thousands of other Iowa farmers—money
Moreover, the Nielsens avoid farming on lands that are while protecting environmental quality and nurturing soil as an
sensitive or have poor soil. Instead, they retire these lands, investment for sustainable yields in the future. By enhancing
supported by government programs that pay farmers to take soil conditions and reducing erosion, no-till farming and other
highly erodible land out of cultivation. Arliss Nielsen restored a conservation measures are benefiting Iowa’s people and Iowa’s
wetland and set aside 80 acres of woodland and prairie grasses environment, cutting down on pollution in the state’s air, water-
along the White Fox River as wildlife habitat. He planted more ways, and ecosystems. Similar success is being seen else-
than 3200 native trees within this riparian buffer strip. “That where in the United States and across the world where these
80 acres is marginal farmland at best,” he explains. “It’s poor approaches are being applied.
soil, some is rocky, and some is wet. This wildlife use is just a No-till farming is not a magic bullet, and it isn’t an ideal
better use of the land all the way around.” Today it’s paying off solution in every location. But in suitable regions, proponents
by providing his family plenty of pheasants to hunt. “I think we say it can help make agriculture sustainable. We will need sus-
can still maintain our profit, with lower input costs using no-till tainable agriculture if we are to feed the world’s human popu-
and cover crops, on fewer acres so that we can still have room lation while protecting the natural environment, including the
for wildlife on other parts of our land,” Arliss says. soils that vitally support our production of food.

Soil: The Foundation for arguably, genetic modification (each of which we explore
below or in Chapter 10). Because most farming and grazing
Sustainable Agriculture that people have practiced so far have depleted soils faster
than they form, it is imperative for our civilization’s future
As the human population has grown, so have the amounts of that we develop sustainable methods of working with soil.
land and resources we devote to agriculture. We can define
agriculture as the practice of raising crops and livestock for
human use and consumption. We obtain most of our food and Soil supports agriculture
fiber from cropland, land used to raise plants for human use, Our agriculture relies on healthy soil in several ways (Figure 9.1).
and from rangeland, or pasture, land used for grazing live- Crop plants depend on soil that contains organic matter to pro-
stock. Today we commandeer more than one out of every vide the nutrients they need for growth. Plants also need soil with
three acres of land on Earth to produce food and fiber for a structure and texture suitable for roots to penetrate deeply. And
ourselves. Rangeland covers 26% of Earth’s land surface, and plants need soil that retains water and makes water and dissolved
cropland covers 12%.
Healthy soil is vital for agriculture, as
well as for forests (Chapter 12) and for the
functioning of Earth’s natural systems. Soil
is not merely lifeless dirt; it is a complex
system consisting of disintegrated rock,
organic matter, water, gases, nutrients, and Organic matter
provides nutrients
microorganisms. Productive soil is a renew- and helps with Soils that retain
water (but drain
able resource. Once depleted, soil may structure and excess water) make
renew itself over time, but renewal generally water retention the right amount
occurs very slowly. If we abuse soil through accessible to plants
careless or uninformed practices, we can
greatly reduce its ability to sustain life.
For these reasons, healthy soil is a H 2 O H 2 O
key component of sustainable agricul- H 2 O H 2 O
ture, agriculture that we can practice in
the same way in the same place far into the Nutrients such Soil structure and
future. Sustainable agriculture allows soil as nitrogen and N P N texture influence
to renew its nutrient content and retain its phosphorus enable N root penetration
character from one crop to the next. Sus- plant growth P P and growth
tainable agriculture also requires reliable
supplies of clean water, minimized use
of fossil-fuel-based fertilizers and pesti-
cides, healthy populations of pollinating Figure 9.1 Crop plants such as wheat depend on healthy soil for nutrients,
234 insects, sustenance of genetic diversity and, organic matter, water retention, and proper root growth.

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