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Effect Of Agriculture On Our Environment

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Effects of Agriculture

on the Environment


Agriculture has changed dramatically, especially since the end of World War II. Food and fibre productivity rose due to new technologies, mechanization, increased chemical use, specialization and government policies that favoured maximizing production. These changes allowed fewer farmers with reduced labour demands to produce the majority of the food and fibre.

Humans, like all other species, exploit their surroundings for the resources they need to survive. Our current exploitation of the world, however, is greater than those of most species. There are many reasons for this exploitation but we will focus on one and that is our technology, which is used for various purposes. Like a few other species, we use tools, but the hand-held tools that we originally used could only adjust extremely local conditions. Today we are able to shape entire regions and our technology has progressed to the point where we can level mountains and control the flow of rivers, something that was simply impossible a relatively short while ago. We can now modify our world relatively easily and quickly.

Agriculture is the major farming activity. Agriculture's scale means not only that large area is directly affected, but that local and even regional climates can be affected. The draining of water from rivers and watersheds for irrigation leads to drier natural habitats. Those rivers that receive runoff from farmland are often poisoned by excessive nutrients and pesticides.

As agriculture has become more intensive, farmers have become capable of producing higher yields using less labour and less land. Growth of the agriculture has not, however, been an unmixed blessing. It, like every other thing, has its pros and cons. Topsoil depletion, groundwater contamination, the decline of family farms, continued neglect of the living and working conditions for farm labourers, increasing costs of production, and the disintegration of economic and social conditions in rural communities. These are the cons of the new improved agriculture.

Environmental impacts have increased, including potential ruin of the soil and water resources essential to both farm productivity and human health.

Agriculture also leads to soil erosion, both through rainfall and wind. This soil can damage the aquatic ecosystems it ends up in, and the loss of nutrients can result in productive farmland becoming barren.

Damage to Soil:

Soil erosion from farmland pressurizes the production of agricultural fields and causes a number of problems in the environment. It takes up to three hundred years for one inch of agricultural topsoil to form so soil that is lost is essentially irreplaceable. The consequences for long-term crop yields have not been sufficiently measured. The amount of erosion varies from one field to another. This depends on the type of soil, the slope of the field, the drainage patterns and the crop management practices. The effects of the erosion vary also. The areas that are better able to sustain erosion without loss of productivity are areas with deep organic loams. This is more sustainable than the areas where topsoil's are shallower.

Erosion removes the surface soils, containing most of the organic matter, plant nutrients, and fine soil particles, which help to retain water and nutrients in the root zone where they are available to plants. Thus it affects the productivity of plants. The remaining, the subsoil, tends to be less fertile, less absorbent and less able to retain pesticides, fertilizers, and other plant nutrients. There are over 17,000 soil types recognized worldwide. They vary widely in structure, erodibility, fertility, and ability to produce crops. A generalized soil profile for a humid, temperate climate is showed. When the natural vegetation is cleared for agriculture, soils become exposed to erosion and loss of soil fertility. The removal of the above-ground natural vegetative cover and subsequent ploughing and preparation for row crop planting, also destroys plant roots which would otherwise help alleviate the soil. Soils disturbed by ploughing and cultivation are flat to erosion by water runoff and wind. Much of the eroded sediment eventually is deposited in streams, rivers, lakes, and the ocean. When the sediments enter waterways, habitat quality for aquatic plants and animals may decline, as well as water quality for human use.

The effects of erosion are also felt elsewhere in the environment. Eroded soil clogs streams, rivers, lakes, and reservoirs, resulting in increased flooding, decreased reservoir capacity, and destruction of habitats for many species of fish and other aquatic life. The eroded soils contain nutrients and other chemicals that are beneficial on farm fields, but can harm water quality when carried away by erosion. As a result, drinking water supplies may contain nitrate or organic chemicals in concentrations that exceed public health standards or surface waters may become clogged with excessive plant growth from the added nutrients.

Farmland should be allowed to recover by allowing it to remain uncultivated and letting natural progression take place. Soil erosion can also be reduced by actively bringing back the original vegetation type. However, soil forming processes can be very slow. Removing highly erodible land from production is another way that can be used to reduce soil erosion. A variety of ploughing and cultivation techniques can be used to reduce soil erosion. These include contour ploughing (following topographic contours) and no-till agriculture (minimal disruption of soil surface). Other strategies include are time ploughing and cultivation to time when the potential for erosion is reduced, crop rotation, planting multicultural, and strip-cropping, terracing, and "grassed" waterways (these are drainage ditches with grass cover). The success of the techniques depends on local soil conditions and the type of crops being planted.

The amounts lost depend also on the type of fertilizer and irrigation used. The three major nutrients in fertilizers are nitrogen, phosphorus, and potassium. Of these, nitrogen is the most readily lost because of its high solubility in the nitrate form. Leakage of nitrate from agricultural fields can elevate concentrations in the original groundwater to levels unacceptable for drinking water quality.

Phosphorus does not leak as readily as nitrate because it is more tightly bound to soil particles. However, it is carried with eroded soils into surface water bodies, where it may cause excessive growth of aquatic plants. If this process precedes far enough, lakes and



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