Plant Nutrients And Fine Soil Particles example essay topic

Effects of Agriculture on the Environment Introduction: 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 reservoirs become choked with decaying mats of algae, which have offensive odours and can cause fish kills from the resulting lack of dissolved oxygen. Potassium, the third major nutrient in fertilizers, does not cause water quality problems because it is not hazardous in drinking water and is not a limiting nutrient for growth of aquatic plants.

It is tightly held by soil particles and so can be removed from fields by erosion, but generally not by leakage. Contamination of Water: Water is the principal resource that has helped agriculture and society to prosper, and it has been a major limiting factor when mismanaged. Water gets contaminated by Farming. The surface runoff carries manure, fertilizers, nitrates, selenium and pesticides into streams, lakes, and reservoirs, in some cases causing unacceptable levels of bacteria, nutrients, or artificial organic compounds.

Similarly, water filters downward through farm fields and carries with it dissolved chemicals, which can include nitrate fertilizers and soluble pesticides. In sufficient quantities these can contaminate groundwater supplies. Another way in which agriculture affects water resources is through the destruction of riparian habitats within watersheds. The conversion of wild habitat to agricultural land reduces fish and wildlife through erosion and sedimentation, the effects of pesticides, removal of riparian plants, and the diversion of water.

The plant diversity in and around both riparian and agricultural areas should be maintained in order to support a diversity of wildlife. This diversity will enhance natural ecosystems and could aid in agricultural pest management. Pesticides: 'Pest' is a general term referring to any undesirable species of plant, animal, or microbe. Any organisms that compete with or otherwise damage crops and livestock are pests. The production of economically valuable crops and livestock in an efficient manner is the goal of agriculture.

Pests reduce efficiency thus there is considerable effort and financial expenditure toward fighting pests. Pesticides include bactericides, insecticides, herbicides, fungicides, and rodenticide's. There are two types of pesticides: Narrow spectrum pesticides, these target specific pest species that are considered less harmful to the environment and Broad spectrum pesticides that affect a wider range of organisms including pests species as well as non-pest and beneficial species. The rapid reproduction rates of many pest species may allow these species to evolve resistance to pesticides; this is called pesticide resistance. Consequently, new and more toxic pesticides must continually be developed. Many pesticides (even narrow spectrum pesticides), unfortunately, have environmental effects beyond their targeted use.

Non-target species may be eliminated by pesticide use. These species may include such beneficial species as pest predators and plant pollinators. Some pesticides are not easily biodegraded in the environment. Long after their target use, these pesticides may persevere in the tissue of plants and animals or in sediments, then re-enter the food web. DDT is one of the most infamous example of the environmental side effects of pesticide use is DDT. It is a chlorinated hydrocarbon that was widely used in the United States as an insecticide until its use was discontinued in the 1970's.

DDT was a fat-soluble compound that did not readily decompose in the environment. DDT concentrated and persisted in the oils and fats of the consumer organism, if consumed by animal. Then DDT could bio magnify and become transferred through food chains. Organisms at the top consumer levels of food chains and long-lived organisms tended to have the highest concentrations of DDT in their tissues. Aquatic food webs were especially vulnerable to the harmful effects of DDT. Long aquatic food chains resulted in high concentrations of DDT in the tissue of top consumers, such as pelicans, ospreys, and bald eagles.

These birds experienced damage to their reproductive systems and consequently they produced thin, easily damaged egg shells. Populations of these species declined significantly. DDT is no longer used in the United States, however, chemical manufacturers are legally allowed to produce DDT and sell it overseas. DDT is often used in the tropics to control mosquitoes and other disease vectors. Integrated Pest Management (IPM) is a common sense scheme to manage pests. It minimizes the environmental damage and maximizes the farm profits.

This is very important for the farmers: to protect their crops sufficiently without having to pay much and earning as much money as possible. IPM makes use of a suite of possible solutions rather than relying only on a single method of pest control, such as relying heavily on pesticides. IPM strategies include using pesticides sensibly and only after determining the specific nature of the pest problem, the proper application rates and the proper timing of application. The greenhouse effects: The earth is surrounded by an atmosphere through which solar radiation is received. The atmosphere is not motionless but contains air, in constant motion, being heated, cooled and moved, water being added and removed along with smoke and dust. Only a small amount of the sun's energy reaches earth and some of this is reflected back into space (from clouds etc.

). When the radiant energy reaches the land surface, most of it is absorbed, being used to heat the earth, evaporate water and to power photosynthetic processes. The earth also radiates energy but, because it is less hot than the sun, this is of a longer wavelength and is absorbed by the atmosphere. The Earths atmosphere, thus acts like the glass of a green house, hence the 'greenhouse effect'. The greenhouse gases are those that absorb the Earths radiation and thus contribute to the greenhouse effect, but water is also a major absorber of energy.

Where there is an increase in the concentration of greenhouse gases (as with CO 2 due to the burning of fossil fuels) this results in an enhanced greenhouse effect - which is of concern as it could lead to climate change (i.e. global warming). Sustainable agriculture integrates three main goals -- environmental health, economic profitability, and social and economic equity. A variety of philosophies, policies and practices have contributed to these goals. People in many different capacities, from farmers to consumers, have shared this vision and contributed to it. So overall, Agriculture is playing a very important role in changing the lifestyle of different people. Agriculture might have made everything easy for us but it still has its cons.

We see the effects of agriculture and how it affects the lives of other species and the environment.