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Реферат: Hydroponics Essay Research Paper The word hydroponics

Название: Hydroponics Essay Research Paper The word hydroponics
Раздел: Топики по английскому языку
Тип: реферат Добавлен 06:41:00 07 ноября 2010 Похожие работы
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Hydroponics Essay, Research Paper

The word ?hydroponics? is thought to have been derived from the Latin

?water working.? Water is the basis for hydroponics. Stated plainly,

hydroponics is the growth of plants without soil. History Though often thought

of as modern and experimental, hydroponics is an ancient practice. Though it

wasn?t known at the time, the Hanging Gardens of Babylon were hydroponic. Less

famous, the Aztecs? Raft Gardens also were hydroponic. In the year 1699,

scientist John Woodward presented a paper before the Royal Society of England.

His paper concerned an experiment that he had performed involving plants grown

in polluted river water versus plants grown in rainwater. This paper attacked

the problem of whether or not the health of plants was determined by the

dissolved solids of the water from which they were grown. In the years

1851-1855, Jean Baptiste Boussingault, French chemist, performed an experiment

of plant growth in quartz and sand cultures with no soil. He used only water and

chemical nutrients. In Germany in 1860, botanist Julius von Sachs published the

first noted nutrient solution formula. In 1865, Wilhelm Knop, a German

agricultural chemist, formed another nutrient solution. In the years 1900-1920,

scientists extended the established number of elements that made a successful

nutrient solution from six to ten. Hydroponic experiments were becoming more

successful with these new elements. In the 1920s William F. Gericke termed this

method ?hydroponics.? Researchers began to realize how this method of growth

without soil could be useful. In the 1940s, mainly during World War II, the

United States armed forces executed hydroponic operations in the South Pacific

to cut down the cost of transportation of fresh fruits and vegetables to the

troops stationed on the islands. In the 1970s, Dr. Alan Cooper developed the

system called ?Nutrient Film Technique? (defined on page 6). Today the use

of hydroponics is becoming more widespread. The Hanging Gardens of Babylon were

a series of solariums filled with plants. Investigations have concluded that an

intricate tunnel and pulley system was used to bring the water from the ground

to the top platform. It is a possibility that the water used was waste from

human inhabitants. This would actually make the gardens hydroponic because

nutrients were added to the plants. The Aztec Floating Gardens or rafts were

called ?chinampas.? They were locates on Lake Tenochtitlan, in Mexico. The

rafts were constructed of rushes and reeds that were bound together with roots.

The Aztecs then took mud from the bottom of the lake and collected it on the top

of the raft. Then vegetables, flowers, and even trees were grown on the rafts.

Some of the roots sprouted down into the lake. The nutrients in the mud and in

the lake helped to produce lush gardens. Pros and Cons Of recent years, the

method of hydroponics has become more widely used to grow healthy plants,

vegetables, fruits, and herbs indoors. Plants can be grown out of soil, their

natural way of growth, because the physiological needs of plants can be met in

an environment void of soil. Nutrition in hydroponics is provided by a liquid

solution made of water and water soluble mineral elements. The plant?s roots

are supported in an ?inert medium.? This inert medium will be discusses

later in this report. Aside from the fact that plants do not physiologically

need soil, there are many other reasons why the use of hydroponics is becoming

more popular. One of these reasons is that hydroponically grown vegetables claim

dramatic increases in vitamin and mineral content as opposed to geoponic (grown

without the use of soil) vegetables. There are also many advantages of

hydroponics related to the caretaking and ease of gardening. This is a chart to

demonstrate some of these reasons: Geoponic Growth Hydroponic Growth Suitable

soil must be found and present. Suitable soil is not necessary. More time and

space is necessary. Space requirements and growth time are reduced. Plants must

be planted; fields must be cultivated, etc. The heavy work is reduced. The plot

must be weeded. There are no weed problems. Crops must be rotated (in commercial

growth). There is no crop rotation. Transplant shock can occur. Little if any

transplant shock occurs. Frequent watering of the plants is necessary. Plants do

not need to be watered as often. There are also benefits of indoor growth versus

outdoor growth: Outdoor Growth Indoor Growth Limited plant growth Conditions and

plant types determined by the grower Too high/ low temperature Temperature

controlled Too much/ little sun Light controlled Too much/ little rain

Controlled water supply Bad weather No storms; no bad weather Still more

benefits of hydroponics are included in an environmental or nutritional

category. Geoponic Growth Hydroponic Growth Soil loses its nutritional value; it

is difficult to measure in terms of fertility Nutritional value of water is

easily measured; plants are always nourished Soil is home to many troublesome

creatures Conditions are sterile, hygienic environment Excess water is used

Water is conserved Disease and pest problems Disease and pests can be controlled

Pesticides contaminate plants Pesticide free Some nutrients are wasted Nutrient

solution can be recycled Soil can not be reused Growing mediums can be recycled

Much soil is necessary Little growing medium is necessary Spacious amounts of

arable land is used Non-arable land can be used Year round crop production uses

fossil fuels Fossil fuels are not used Not very pest resistant More pest

resistant Sometimes artificial ripening agents must be added to the produce

Plants are always vine-ripened Hydroponics, in a small scale, has been used

efficiently by farmers, on a commercial level, for years. These hydroponic

farmers have many advantages over farmers that farm using soil. Some of these

advantages have been summarized in the charts above. By using hydroponics. A

farmer is basically creating his own perfect nature. His time of growth, yield

of growth, and quality of products can be predicted and controlled while the

geoponic farmer has to deal with unforeseen events of nature. In addition,

hydroponic vegetables and fruits have been proven to be healthier than soil

grown. While the pros heavily outweigh the cons of hydroponics, there are some

disadvantages. Some of these are: q The cost of setting up a hydroponic

system can be high. q In a commercial environment, knowledge and skill

are needed to achieve maximum production q The benefits of helpful soil

life is lacking q The sharing of nutrient solutions can spread disease

and pests q There are some plant varieties that are not suitable for

hydroponic growth q While plants react quickly to good conditions, they

react just as quickly to bad conditions Growing Techniques The one main

condition of hydroponics that must remain stable is the water supply. There are

many techniques of bringing water to the plants. Nutrient Film Technique (NFT):

This is the traditional form of water distribution. The nutrients are supplied

to the roots by growtubes. The remainder of the solution that is not used is

pulled back to a reservoir by way of gravity. Drip or Micro-Irrigation: This

method has been used increasingly. A minimal amount of water is used, with the

plant receiving the full benefit. A submersed pump provides nutrients to feed

lines that constantly drip water over the plants and the roots. An additional

tube underneath receives the excess solution to be reused. Aeroponics: The roots

of the plants are hanging in an oxygen-rich nutrient solution. This allows for

easy inspection and pruning. Air pumps provide oxygen and other pumps spray the

roots with water. Deep Water Culture: This is another form of aeroponics. The

roots of a plant system are submerged in water. A ventilator keeps the roots

oxygenated. Flood and Drain: These systems resemble NFT systems. A submersed

pump connected to a timer systematically floods a plastic growing bin. The inert

medium and the roots are drenched, and then drained by way of gravity. Rockwool

(which will be discussed further below) is the most common medium used with the

Flood and Drain System. Passive Planters/ Hydroculture: This is the most common

method and will be used in the project. These systems do not need a water or air

pump, hence the name ?passive.? Planters using this system use an

uncontaminated, permeable medium. A nutrient store in the base of the container

used for growth allows the plants to take the exact amount of water that they

need. Inert Growth Mediums In spite of the fact that hydroponically grown plants

do not use soil, something must still anchor them. There are many materials that

can be used as these mediums. The type of medium used depends on many factors,

including the size and type of plants, and the type of hydroponic system used.

This section will discuss a few of the main mediums. Heydite and Hydrocorn:

Heydite is porous shale that allows for free drainage and air space. Hydrocorn

is clay pellets. Both are easy to reuse and clean and they are both good for

continuous drip systems. They provide secure foundation for large plants.

Rockwool: Rockwool is made by melting basalt rock and chalk into lava, then

pulling it into fibrous cubes. It insulates well and provides a good

water/oxygen balance. Rockwool is used in continuous drip or flood and drain

systems. Most often Rockwool is only used one time. Perlite and Vermiculite:

Perlite is a light white material that is often used in soil. Vermiculite is a

flaky shiny substance that is often mixed with Perlite They do not provide

enough support for large plants. They are often used when plants are young or

seedlings. Some hydroponic systems do not require any medium at all and use some

other means of support.

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