Environmental Engineering Reference
In-Depth Information
increase the organic content. Mechanical measures including contouring, terrace cultiva-
tion, and contour hedges can reduce erosion and increase yields. In the following sections,
we will look at some measures to reduce impact. They are by no means an exhaustive list
but serve as examples of more sustainable practices farmers today.
6.5.1.2 Soil Erosion
In respect to the impact of farming practices on soil erosion, the Franklin Sustainability
Project in New Zealand evaluated different methods, including raised access ways,
benched headlands, silt ins and traps and contour drains for erosion minimization
(Hicks and Anthony, 2001). It had been estimated that 98 mm of top soil has been lost
since 1952. Grasses and sedges were effective as sediment ilters and in combination with
benched headlands can be very effective for trapping sediment but do not prevent erosion.
Appropriate water management techniques are required to avoid subsidence and ground-
water depletion. Cattle herds and locks should be limited to avoid excessive trampling
and overpasturing. Waterlogging should be avoided to prevent loss of the land to salini-
zation. Adequate drainage is required to leach out the salts and remove the excess water
from the soil.
6.5.1.3 Integrated Crop Management
The British Agrochemical Association has developed an approach called
Integrated Crop
Management
to “avoid waste, enhance energy eficiency and minimize pollution” (ECIFM,
2014). This approach advocates (a) crop rotation, (b) selection of appropriate cultivation
techniques and seed varieties, (c) minimization of fertilizers, pesticides, and fossil fuels,
(d) landscape maintenance, and (e) encouragement of wildlife habitats. Use of farm-pro-
duced inputs for fuels, pesticides, and fertilizers is encouraged. Soils are protected to
(a) minimize energy use, (b) reduce erosion, and (c) reverse adverse effects on beetles,
spiders, and earthworms. Crop production that is appropriate for the climate, soil type,
and topography are maintained. Trials have shown that with such practices, (a) costs are
reduced by 20% to 30%, (b) pesticide use is reduced by 30% to 70%, and (c) there is a reduc-
tion in requirement for nitrogen by 16% to 25%. The results also show that biodiversity was
increased and nitrate leaching and soil erosion were reduced.
Livestock generate signiicant stressor impacts on the geoenvironment, such as over-
grazing, erosion of the soil, river and lake pollution, desertiication, and deforestation
(Regenstein, 1991). Their numbers have increased substantially to the point where they
now outnumber humans 3:1 (Goodland, 1998). Incentives and taxes could be used to pro-
mote good environmental practice in food and agriculture. Reduction in water use and
recycling of manure can be practiced. Cattle feedlots provide the most signiicant impact.
Sheep generate lesser impact since they graze on more natural grassland.
Biotechnology has been employed to increase food quality and production through the
availability of transgenic plants. The main objectives are to develop plants that are resis-
tant to bacteria, fungus, viruses, and environmental stress. At this point, conventional
crop breeding is commanding more attention, due in part to the need to broaden capabili-
ties and alternatives to the production of genetically altered plants.
Optimized uses of both fertile and fragile soils together with measures to rejuvenate pro-
duction on degraded lands are procedures that can be pursued. Lower quality soils could
support more species than high-yield agricultural lands (Dobson et al., 1997). Planting
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