Environmental Engineering Reference
In-Depth Information
1950
1985
2000
2005
2010
2020
Figure 3.2
Deforestation of the Island of Borneo from 1950 to 2005 and projections into 2020.
Cartographer Hugo Ahlenius, UNEP/GRID-Arendal, 2007.
In the United States, virgin forests shrunk from 820 million acres in 1620 to around 138
million acres in 1920 (Greeley, 1925). Certainly, not all the forest was lost to agriculture but
also to the exploitation of timber; however, most of that land was converted to agriculture and
nonforest uses with an irreversible loss of the benefits supplied by pristine forests. The United
States has not been alone in losing virgin forests to commercial activities. By the year 2030, it
is expected that 55 percent of the Amazon rainforest will be cleared for cattle ranches,
subsistence agriculture, commercial agriculture, logging, and infrastructure projects (World
Wildlife Fund [WWF], 2007). Borneo and Sumatra, home of the most diverse tropical forests
in the world, are being deforested at an alarming pace for palm oil plantations and other
cultivars. Figure 3.2 shows the extent of the rate of deforestation of the island of Borneo from
1950 to 2005 and projections toward 2020.
Fertilization
According to the International Fertilizer Industry Association (www.fertilizer.org), “any natural
or manufactured material that contains at least 5% of one or more of the three primary
nutrients—nitrogen (N), phosphorus (P), or potassium (K)—is considered a fertilizer.” Typical
application rates of these three fertilizers for selected crops are shown in Figure 3.3. In addi-
tion, sulphate and magnesium complete the list of macronutrients that are regularly applied as
fertilizers. These five nutrients can be delivered to the ground individually, or as a combina-
tion of two, using the fertilizers listed in Table 3.1.
