Environmental Engineering Reference
In-Depth Information
trees for shelter can also help to (a) reduce evaporation and transpiration by 13% to 25%
(Mari et al., 1985), (b) reduce wind erosion, and (c) increase crop yields such as corn by 10%
to 74% (Gregersen et al., 1989).
6.5.1.4 Water Quality
The Farm Waste Management Plan of the United Kingdom (Saha, 2001) has listed the fol-
lowing items for pollution control:
• Delay ploughing in of crop residues
• Reducing the use of fertilizers, manure, and sewage sludge
• Sowing autumn crops early
• Managing farm waste carefully
With regard to water quality, Sagardoy (1993) listed the following items to avoid water
pollution:
• Development of water quality monitoring schemes
• Optimization of the use of farm inputs and other agricultural activities that impact
wetlands
• Establishment of water quality criteria for agriculture
• Prevent soil runoff and sedimentation
• Proper disposal of animal and human wastes
• Ionization of agricultural chemicals for pest management
• Education of the community to minimize impact on water quality and ensure
food safety
The capability of soils for retention of contaminants is a good means for reducing the
threat or impact of contamination of groundwater. A case in point could be the cereal cul-
tivation in northeastern France that has led to pollution of the Rhine Valley groundwater
by nitrates (Bernard et al., 1992). These agricultural soils contained much lower organic
contents than forest soils. Considering that forest soils with their higher organic contents
will show greater capability in retaining the contaminants and converting the nitrates to
N 2 O through denitriication, it would appear that conversion of these agricultural lands
through reforestation can signiicantly reduce groundwater pollution.
Although attention is normally given to soil permeability in consideration of transport
of fertilizers in the ground, the attention received by the underlying geology has not been
as signiicant. This oversight can lead to serious consequences. The example of Brittany,
France, with underlying densely fractured and weathered granite rocks is a good dem-
onstration. These densely fractured weathered rocks allow iniltration of contaminated
water, in contrast to metamorphic schists that prevent seepage into the underlying rock
(Chamley, 2003). Nitrates and phosphates from farms are retained by the granite that can
then contaminate areas downstream. Geological maps and corresponding laboratory data
on the rock properties are useful tools in predicting the impact of pollution from farm
fertilizers. Réunion, a sloped territory with increasing agricultural activities, urban and
tourist areas produced a map in the year 2000 for such purposes.
Search WWH ::




Custom Search