Agriculture Reference
In-Depth Information
Box 18.1 Selection of findings highlighting the long-term
impact of agriculture and related activities on natural
resources (Wood
et
al
. 2001 and Millennium Ecosystem
Assessment 2005)
More land was converted to cropland since 1945 than in the 18th and 19th centuries
combined, and now about one-quarter (24%) of Earth's terrestrial surface has been
transformed to cultivated systems.
Moderate to severe soil degradation occurs on 52% of global agricultural lands.
Human activities now produce more biologically usable nitrogen than is produced by all
natural processes combined.
More than one-half of all the manufactured nitrogen fertiliser (first produced in 1913)
ever used on the planet has been applied since 1985.
The flow of nitrogen to the oceans has doubled since 1860.
Water withdrawals from rivers and lakes for irrigation, household and industrial use
doubled in the last 40 years.
Humans now use between 40% and 50% of the freshwater running off land to which
most of the population has access.
Total food production increased by about two-and-a-half times while the number of
people in the world doubled from 3 billion to 6 billion between 1960 and 2000.
Despite the growth in per capita food production since the 1970s, an estimated 852
million people were undernourished in 2000-2002, up 37 million from 1997-1999.
The number of species on the planet is declining and the species distribution is becoming
more homogenous.
Genetic diversity has declined globally, particularly among cultivated species.
Water and air pollution were more problematic in organic farming because of the reliance on
manures, and Kasperczyk and Knickel also raised a common concern that economic pres-
sures to maximise short-term production may compromise the beneficial aspects of organic
agriculture.
Chapter 4 began with two important points that are worth restating here. First, organic
growers are not homogeneous. Some farmers use 'substitution-based' approaches and are seeking
premium prices for their goods. Others are 'subsistence' producers using organic methods by
default. Between these groups are a range of philosophically committed organic growers who are
more motivated by environmental and health issues. Second, Letourneau and van Bruggen (see
Chapter
4
) question the use of 'simplified' terms, such as organic and conventional, preferring
instead to focus on specific management practices and agroecological mechanisms. By focusing
on actual practices and processes within farming systems, it is expected that the observed effects
of certain organic practices can be more clearly quantified and interpreted. The finding can also
be generalised for other locations, crops or farming systems.
In this Chapter, key conclusions from earlier chapters have been compiled and summa-
rised. Many themes were consistently reiterated in the various chapters, confirming the impor-
tance of those themes across a wide range of settings. Rather than speculating on the future of
organic agriculture and its possible impact on world food security and the environment, this
