Reality Cheques - Agri-culture: Reconnecting People, Land and Nature - page 62

Traditional villages in rural areas include settlements, paddy fields, crop fields and
forested hills or mountains, all as linked landscape. The systems were dependent on
all their parts. The decline of farming in the uplands, together with loss of forests,
threatens the stability of whole watersheds. 24
In China, the 500,000 hectares of wetlands that have been reclaimed for
crop production during the past 50 years have meant the loss of flood-
water storage capacity of some 50 billion cubic metres, a major reason
for the US$20 billion flood damage caused in 1998. 25 In many agricult-
ural systems, over-intensive use of the land has resulted in sharp declines
in soil organic matter and/or increases in soil erosion, some of which, in
turn, threatens the viability of agriculture itself. In South Asia, for
example, one quarter of farmland is affected by water erosion, one fifth
by wind erosion, and one sixth by salinization and waterlogging. 26
Putting a value on wetlands and watercourses, so that we can calculate
how much is lost when they are damaged or destroyed, is not a trivial task.
Economists have no agreed value for wetlands, though various studies
indicate that individual bodies can provide several million dollars of free
services to nearby communities for waste assimilation and treatment. A
recent US Department of Agriculture study put wetland monetary value
at US$300,000 per hectare per year. Another way to assess value is to
investigate how much people pay to visit wetlands, whether to watch or
photograph biodiversity, or indeed to shoot it. In the US, it is estimated
that 50 million people each year spend US$10 billion observing and
photographing wetland flora and fauna, 31 million anglers spend US$16
billion on fishing, and 3 million waterfowl hunters spend nearly US$700
million dollars annually on shooting it. A recent meta-analysis of econ-
omic studies of people's willingness to pay for recreational services of
wetlands and watercourses puts the average value in Europe at UK£20 to
UK£25 per person per hectare per year. 27 Thus, each hectare of wetland
converted to another purpose means the loss of at least UK£20 of value
to the public. There are, of course, limitations in these exercises, as monetary
values cannot be allocated to all uses.
One of the most serious side effects of agriculture is the leaching and
run-off of nutrients, and their disruption of water ecosystems. Eutroph-
ication is the term used to describe nutrient enrichment of water that leads
to excessive algal growth, disruption of whole food webs and, in the worst
cases, complete eradication of all life through deoxygenation. The most
notorious example is the Gulf of Mexico dead zone, an area of 5000 to
18,000 square kilometres of sea that has received so much nutrient input
that all aquatic life has been killed. The cost of farm overuse of nutrients
in the Mississippi Basin is thus borne by the fishing families of Louisiana.