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Agriculture  
  
1870   01:15 صباحاً   date: 9-10-2015
Author : Cooper, Elmer L., and L. Devere Burton
Book or Source : Agriscience: Fundamentals and Applications
Page and Part :


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Date: 26-10-2015 1859
Date: 22-10-2015 1818
Date: 21-10-2015 1793

Agriculture

Agriculture is both an occupational practice and a subject to be studied. Farmers, horticulturists, and ranchers are examples of individuals who grow things for human use. Scientific researchers who experiment to improve plant and animal productivity; historians who examine the development of agrarian processes and the industry; and ecologists who study fields and fish ponds as managed ecosystems are examples of those who pursue agriculture as an area of academic interest. Decision making, leadership, research, and many other roles in modern agriculture require a college education in fields such as agronomy, animal husbandry, pathology, floriculture, agri­cultural economics, and mariculture.

Farming began early in the development of human society. The earli­est ancestors of modern humans were scavengers, hunters, and gatherers. The search for food was an ongoing process, and the collected items were consumed shortly after being found. The abundance of food was very de­pendent on periodic variations in weather and natural disasters such as flood, fire, drought, and severe cold. The beginnings of agriculture rest with in­dividuals who learned to plant seeds of edible crops or keep a small herd of goats or maintain a flock of chickens.

The transition to sustainability involved using the milk of the goats, or gathering eggs, rather than butchering animals as soon as possible for meat. Some cultures were ingenious in developing ways to obtain multiple sus­tainable resources from a single species. Examples of this are the cattle herded by the Masai of present-day Kenya and Tanzania, and reindeer man­aged by many indigenous peoples of northern Eurasia. These animals pro­vide resources such as milk, meat from excess calves, and even blood as food, plus leather and bone for clothes, tools, and ornaments.

Globally, a variety of cultural patterns developed as family units grew into villages, villages into towns, and ultimately towns grew into the com­plex urban cultures present throughout the world today. With the concen­tration of humans into cities, the ability of the individual to produce food for a family unit declined to the point where as of the twenty-first century a large number of individuals are totally dependent on others for their nour­ishment. In some societies this involves a daily trip to the marketplace where family farmers sell the products of their efforts. In many less-developed countries a great deal of the food consumed is still self-produced or obtained from small agricultural units in this manner. In more developed and indus­trialized countries, the local market has been extensively replaced by large chain stores that distribute packaged and processed foods that are produced by large commercial farms, ranches, and orchards. However, even in these highly developed areas, there are many who prefer locally grown foods and flock to farmers markets, organic food stores, and other small businesses.

A wild rice plant growing in Ocala, Florida. For the earliest ancestors of modern humans, the search for food was an ongoing process.

Modern agriculture is now a big business, which is driven by ever- increasing scientific knowledge. The family farm found throughout America during the twentieth century is disappearing. These traditional, somewhat self-contained operations, where field crops were grown to produce grain, and gardens cultivated for vegetables, and a mixture of animals including cows, pigs, chickens, and sheep produced food and necessary materials such as leather and wool, are no longer economically practical. They have, in the industrialized world, given way to corporate farms that operate in much the same way as other large businesses. These agricultural units include not only the obvious specialized food-producing dairy farms, poultry operations, ap­ple orchards, cattle ranches, and expansive wheat, corn, and soybean fields, but also such industries as catfish farms, shrimp nurseries, and oyster cul­tures. Agriculture also produces nonedible products such as tobacco and cot­ton, and grain for the production of methanol, a substitute for fossil fuels.

The agricultural operations of the past depended greatly on the intu­ition and experience of the family unit concerning when to plant, how to recognize a disease in the herd, and the best time to harvest. This infor­mation was passed from generation to generation. Decisions are now based on research and development carried out by university and private industry scientists. At one time it was a matter of knowing which farmer in the town­ship had the best bull and bartering with him or her to bring this fine spec­imen to one’s herd of females. Today genetic research has resulted in the development of the best bull in the country, and a farmer can order frozen sperm from across the continent. In fact, in this new millennium, the com­mercial distribution of cloned embryos of individual livestock specimens with the best possible characteristics is at hand.

Genetic engineering has virtually unlimited potential for producing frost- and disease-resistant crops, high-yield animals, products with a longer shelf life and a better flavor, and a multitude of other advances. Biotech­nology, which has the great promise of advancing agriculture, has potential deleterious effects. For example, it could result in the herbicide-resistant gene inserted in a grain variety being transferred through unintended hy­bridization into a natural population of a related “weedy” or deleterious species, allowing it to prosper out of control.

Not only has modern agriculture introduced additional science into the barnyard, it has also brought in the economists, the lawyers, the television commentators for agri-business shows, and a multitude of businesspeople who advertise and market the product. This is a far cry from a farmer sell­ing his best calf at the end of the summer at the county fair.

Finally, there is another element of modern agriculture. When farms were spread out across the countryside interspersed with wood lots, or when cattle production involved letting the herd range over hundreds of acres during the summer, the local impact on the land and environment was rel­atively low (although the total impact was high, given the large number of acres devoted to agriculture). Modern, high-intensity agriculture with fields cultivated using tractors as large as elephants, fertilizers, pesticides, and ir­rigation systems is a potential threat to the environment. These techniques can place high demands on freshwater sources and have the potential for in­troducing toxic contaminants and excess nutrients into streams and rivers or promoting soil erosion. High-density animal production, such as hog farms in North Carolina, cattle feed lots in the Midwest, and turkey and dairy farms in the Shenandoah Valley, produce fecal contamination that can pollute waterways with bacteria and cause cultural eutrophication of aquatic ecosystems due to excess nutrients. Even the best planned containment of animal wastes can break down under the flood conditions of hurricanes and high rainfall years.

The human population is growing at such a high rate that humans in less-developed countries will surely starve and die without pulses of progress such as the green revolution that produced high-quality rice for underdeveloped countries in the 1960s. Prevention of this situation is the hope of industrial and biological technology advances that are sure to happen dur­ing the twenty-first century. However, this is a double-edged sword. Agri­cultural progress without due attention to environmental impacts has the potential for creating a world that will not be desirable to live in for the people supported by its products.

 

References:

Cooper, Elmer L., and L. Devere Burton. Agriscience: Fundamentals and Applications, 3rd ed. Albany, NY: Delmar Publishers, 2000.

National Research Council. Genetically Modified Pest-Protected Plants. Report by Com­mittee on Genetically Modified Pest-Protected Plants. Washington, DC: National Academy Press, 2000.

Smith, Bruce D. Emergence of Agriculture. New York: Freeman and Company/Worth Publishers, 1999.

 

 

 

 




علم الأحياء المجهرية هو العلم الذي يختص بدراسة الأحياء الدقيقة من حيث الحجم والتي لا يمكن مشاهدتها بالعين المجرَّدة. اذ يتعامل مع الأشكال المجهرية من حيث طرق تكاثرها، ووظائف أجزائها ومكوناتها المختلفة، دورها في الطبيعة، والعلاقة المفيدة أو الضارة مع الكائنات الحية - ومنها الإنسان بشكل خاص - كما يدرس استعمالات هذه الكائنات في الصناعة والعلم. وتنقسم هذه الكائنات الدقيقة إلى: بكتيريا وفيروسات وفطريات وطفيليات.



يقوم علم الأحياء الجزيئي بدراسة الأحياء على المستوى الجزيئي، لذلك فهو يتداخل مع كلا من علم الأحياء والكيمياء وبشكل خاص مع علم الكيمياء الحيوية وعلم الوراثة في عدة مناطق وتخصصات. يهتم علم الاحياء الجزيئي بدراسة مختلف العلاقات المتبادلة بين كافة الأنظمة الخلوية وبخاصة العلاقات بين الدنا (DNA) والرنا (RNA) وعملية تصنيع البروتينات إضافة إلى آليات تنظيم هذه العملية وكافة العمليات الحيوية.



علم الوراثة هو أحد فروع علوم الحياة الحديثة الذي يبحث في أسباب التشابه والاختلاف في صفات الأجيال المتعاقبة من الأفراد التي ترتبط فيما بينها بصلة عضوية معينة كما يبحث فيما يؤدي اليه تلك الأسباب من نتائج مع إعطاء تفسير للمسببات ونتائجها. وعلى هذا الأساس فإن دراسة هذا العلم تتطلب الماماً واسعاً وقاعدة راسخة عميقة في شتى مجالات علوم الحياة كعلم الخلية وعلم الهيأة وعلم الأجنة وعلم البيئة والتصنيف والزراعة والطب وعلم البكتريا.




العتبة العباسية تطلق مسابقة فن التصوير الفوتوغرافي الثانية للهواة ضمن فعاليات أسبوع الإمامة الدولي
لجنة البرامج المركزيّة تختتم فعاليّات الأسبوع الرابع من البرنامج المركزي لمنتسبي العتبة العباسيّة
قسم المعارف: عمل مستمر في تحقيق مجموعة من المخطوطات ستسهم بإثراء المكتبة الدينية
متحف الكفيل يشارك في المؤتمر الدولي الثالث لكلية الآثار بجامعة الكوفة