Page 256 - Environment: The Science Behind the Stories

Air pollution
Nitrogen oxides Nitrogen oxides

Evaporation
Evaporation

Phosphates,
ammonia,
Runoff
Runoff ammonium,
and nitrates Inorganic
fertilizer
Eutrophication
Infiltration
Infiltration

Contamination
Contamination
of ground water
of groundwater
Figure 9.25 Overapplication of fertilizers has impacts beyond the farm field, because nutrients not
taken up by plants end up elsewhere. Nitrates can leach into aquifers and contaminate drinking water. Runoff of
phosphates and nitrogen compounds can alter the ecology of waterways through eutrophication. Compounds
such as nitrogen oxides may pollute the air.

once their plants have sprouted to determine how much more using intensive methods that degrade the land they own if
to add. “We’re putting more nitrogen where the crop can use such practices are not profitable in the long run. But land
it and less nitrogen on or in the ground where the crop can’t degradation often unfolds gradually, whereas farmers and
use it,” Todd Nielsen says. In addition, buffer strips of veg- ranchers generally cannot afford to go without profits in the
etation they planted along field edges and along the river on short term, even if they know conservation is in their long-
their property help to capture nutrient runoff along with any term interests. For this reason, we have increasingly devel-
eroded soils. oped public policy to encourage conservation measures.
Sustainable agriculture embraces the use of organic
fertilizers, as they can provide some benefits that inorganic
fertilizers cannot. Organic fertilizers provide not only nutri- Some policies worsen land degradation
ents, but also organic matter that improves soil structure,
nutrient retention, and water-retaining capacity. The use Many nations spend billions of dollars in government subsi-
of organic fertilizers is not without cost, though. When dies to promote agricultural production. In many cases these
manure is applied in amounts needed to supply sufficient subsidies fund practices that are not economically and envi-
nitrogen for a crop, it may introduce excess phosphorus, ronmentally sustainable, such as growing water-thirsty crops
which can run off into waterways. Thus, the Nielsens apply in desert regions. Roughly one-fifth of the income of the aver-
manure, but they are careful not to use too much. Accord- age U.S. farmer comes from subsidies. Proponents of such
ingly, sustainable approaches do not rely solely on organic subsidies stress that the uncertainties of weather make profits
fertilizers, but integrate them with the targeted use of inor- and losses from farming unpredictable from year to year. To CHAPTER 9 • So I l AN d A gr I culT ure
ganic fertilizer. persist, these proponents say, farmers need some way of being
compensated in bad years. This may be the case, but subsidies
can encourage people to cultivate land that would otherwise
Agricultural Policy not be farmed; to produce more food than is needed, driv-
ing down prices for other producers; and to practice methods
Governments have long sought ways to encourage agri- that degrade the land. Thus, opponents of subsidies argue that
cultural production. More recently, they have also sought subsidizing environmentally destructive agricultural prac-
ways to lessen the environmental impacts and external tices is unsustainable. They suggest that a better model is for
costs (p. 164, 183) of agriculture. In theory, the market- farmers to buy insurance to protect themselves against pro-
place should discourage people from farming and grazing duction shortfalls. 255

M09_WITH7428_05_SE_C09.indd 255 12/12/14 2:59 PM