nutrient elements. Because modern agroecosystems are entirely dependent on human intervention, they would not persist but for that intervention. It is for this reason that they are sometimes referred to as artificial systems as opposed to natural systems that do not require intervention to persist through space and time.

Definitions of agroecosystems often include the entire support base of energy and material subsidies, seeds, and chemicals, and even a sociopolitico-economic matrix in which management decisions are made. Crossley (1984) stated that while this is logical, he preferred to designate the individual field as the agroecosystem because it is consistent with designating an individual forest catchment or lake as an ecosystem. He envisions the farm system as consisting of a set of agroecosystems — field with similar or different crops — together with support mechanisms and socioeconomic factors contributing to their management.

Agroecosystems retain most if not all the functional properties of natural ecosystems — nutrient conservation mechanisms, energy storage and use patterns, and regulation of biotic diversity

Text 10

FARMING AND NATURAL RESOURCES

Water. When the production of food and fiber degrades the natural resource base, the ability of future generations to produce and flourish decreases. The decline of ancient civilizations in Mesopotamia, the Mediterranean region, Pre-Columbian southwest U.S. and Central America is believed to have been strongly influenced by natural resource degradation from non-sustainable farming and forestry practices. Water is the principal resource that has helped agriculture and society to prosper, and it has been a major limiting factor when mismanaged.

Water quality. The most important issues related to water quality involve salinization and contamination of ground and surface waters by pesticides, nitrates and selenium. Salinity has become a problem wherever water of even relatively low salt content is used on shallow soils in arid regions and/or where the water table is near the root zone of crops. Tile drainage can remove the water and salts, but the disposal of the salts and other contaminants may negatively affect the environment depending upon where they are deposited. Temporary solutions include the use of salttolerant crops, low-volume irrigation, and various management techniques to minimize the effects of salts on crops. In the long-term, some farmland may need to be removed from production or converted to other uses. Other uses include conversion of row crop land to production of drought-tolerant forages, the restoration of wildlife habitat or the use of agroforestry to minimize the impacts of salinity and high water tables. Pesticide and nitrate contamination of water can be reduced using many of the practices

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discussed later in the Plant Production Practices and Animal Production Practices sections.

Energy. Modern agriculture is heavily dependent on non-renewable energy sources, especially petroleum. The continued use of these energy sources cannot be sustained indefinitely, yet to abruptly abandon our reliance on them would be economically catastrophic. However, a sudden cutoff in energy supply would be equally disruptive. In sustainable agricultural systems, there is reduced reliance on non-renewable energy sources and a substitution of renewable sources or labor to the extent that is economically feasible.

Air. Many agricultural activities affect air quality. These include smoke from agricultural burning; dust from tillage, traffic and harvest; pesticide drift from spraying; and nitrous oxide emissions from the use of nitrogen fertilizer. Options to improve air quality include incorporating crop residue into the soil, using appropriate levels of tillage, and planting wind breaks, cover crops or strips of native perennial grasses to reduce dust.

Soil. Soil erosion continues to be a serious threat to our continued ability to produce adequate food. Numerous practices have been developed to keep soil in place, which include reducing or eliminating tillage, managing irrigation to reduce runoff, and keeping the soil covered with plants or mulch.

Sustainable production practices involve a variety of approaches. Specific strategies must take into account topography, soil characteristics, climate, pests, local availability of inputs and the individual grower's goals. Despite the site-specific and individual nature of sustainable agriculture, several general principles can be applied to help growers select appropriate management practices:

*Selection of species and varieties that are well suited to the site and to conditions on the farm;

*Diversification of crops (including livestock) and cultural practices to enhance the biological and economic stability of the farm;

*Management of the soil to enhance and protect soil quality;

*Efficient and humane use of inputs; and

*Consideration of farmers' goals and lifestyle choices.

Selection of site, species and variety. Preventive strategies, adopted early, can reduce inputs and help establish a sustainable production system. When possible, pest-resistant crops should be selected which are tolerant of existing soil or site conditions. When site selection is an option, factors such as soil type and depth, previous crop history, and location (e.g. climate, topography) should be taken into account before planting.

Diversity. Diversified farms are usually more economically and ecologically resilient. While monoculture farming has advantages in terms of efficiency and ease of management, the loss of the crop in any one year could put a farm out of business and/or seriously disrupt the stability of a community dependent on that crop. By growing a variety of crops, farmers

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spread economic risk and are less susceptible to the radical price fluctuations associated with changes in supply and demand.

For example, in annual cropping systems, crop rotation can be used to suppress weeds, pathogens and insect pests. Also, cover crops can have stabilizing effects on the agroecosystem by holding soil and nutrients in place, conserving soil moisture with mowed or standing dead mulches, and by increasing the water infiltration rate and soil water holding capacity. Cover crops in orchards and vineyards can buffer the system against pest infestations by increasing beneficial arthropod populations and can therefore reduce the need for chemical inputs. Using a variety of cover crops is also important in order to protect against the failure of a particular species to grow and to attract and sustain a wide range of beneficial arthropods.

Optimum diversity may be obtained by integrating both crops and livestock in the same farming operation. This was the common practice for centuries until the mid-1900s when technology, government policy and economics compelled farms to become more specialized. Mixed crop and livestock operations have several advantages. First, growing row crops only on more level land and pasture or forages on steeper slopes will reduce soil erosion. Second, pasture and forage crops in rotation enhance soil quality and reduce erosion; livestock manure, in turn, contributes to soil fertility. Third, livestock can buffer the negative impacts of low rainfall periods by consuming crop residue that in "plant only" systems would have been considered crop failures. Finally, feeding and marketing are flexible in animal production systems. This can help cushion farmers against trade and price fluctuations and, in conjunction with cropping operations, make more efficient use of farm labor.

Soil management. A common philosophy among sustainable agriculture practitioners is that a "healthy" soil is a key component of sustainability; that is, a healthy soil will produce healthy crop plants that have optimum vigor and are less susceptible to pests. While many crops have key pests that attack even the healthiest of plants, proper soil, water and nutrient management can help prevent some pest problems brought on by crop stress or nutrient imbalance. Furthermore, crop management systems that impair soil quality often result in greater inputs of water, nutrients, pesticides, and/or energy for tillage to maintain yields.

In sustainable systems, the soil is viewed as a fragile and living medium that must be protected and nurtured to ensure its long-term productivity and stability. Methods to protect and enhance the productivity of the soil include using cover crops, compost and/or manures, reducing tillage, avoiding traffic on wet soils, and maintaining soil cover with plants and/or mulches. Conditions in most California soils (warm, irrigated, and tilled) do not favor the buildup of organic matter. Regular additions of organic matter or the use of cover crops can increase soil aggregate stability, soil tilth, and diversity of soil microbial life.

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Efficient use of inputs. Many inputs and practices used by conventional farmers are also used in sustainable agriculture. Sustainable farmers, however, maximize reliance on natural, renewable, and on-farm inputs. Equally important are the environmental, social, and economic impacts of a particular strategy. Converting to sustainable practices does not mean simple input substitution. Frequently, it substitutes enhanced management and scientific knowledge for conventional inputs, especially chemical inputs that harm the environment on farms and in rural communities. The goal is to develop efficient, biological systems which do not need high levels of material inputs.

Growers frequently ask if synthetic chemicals are appropriate in a sustainable farming system. Sustainable approaches are those that are the least toxic and least energy intensive, and yet maintain productivity and profitability. Preventive strategies and other alternatives should be employed before using chemical inputs from any source. However, there may be situations where the use of synthetic chemicals would be more "sustainable" than a strictly nonchemical approach or an approach using toxic "organic" chemicals. For example, one grape grower switched from tillage to a few applications of a broad spectrum contact herbicide in the vine row. This approach may use less energy and may compact the soil less than numerous passes with a cultivator or mower.

Consideration of farmer goals and lifestyle choices. Management decisions should reflect not only environmental and broad social considerations, but also individual goals and lifestyle choices. For example, adoption of some technologies or practices that promise profitability may also require such intensive management that one's lifestyle actually deteriorates. Management decisions that promote sustainability, nourish the environment, the community and the individual.

Genetic engineering is the the use of various methods to manipulate the deoxyribonucleic acid (DNA)of cells to produce biological products or to change hereditary traits. Techniques used include using needles to insert DNA into an ovum, hybridomas (hybrids of cancer cells and of cells that make a desired antibody), and recombinant DNA, in which the DNA of a desired gene is inserted into the DNA of a bacterium. The bacterium then reproduces itself, yielding more of the desired gene. Another type is the polymerase chain reaction (PCR) which referrs to a lab process in which a particular DNA segment is quickly replicated to create a large, easily analyzable sample. The process makes perfect copies of DNA fragments and is used in DNA fingerprinting.

The Human Genome Project, an ambitious attempt to map each human gene, was completed in 2003. Armed with this information, scientists hope to treat and cure many types of chronic diseases such as cancer, diabetes, Huntington's disease, and neurofibromatosis (Elephant Man's disease.)

Many genetically engineered products are already on the market. These include bacteria designed to digest oil slicks and industrial waste

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products, growth hormones for both humans and cows, drugs such as interferon and insulin, and plants that are resistant to insects and disease.

Genetic engineering techniques have also been used in the alteration of livestock and laboratory animals. The most famous of these animals was Dolly, the first cloned sheep. Genetically engineered products require the approval of at least one U.S. government agency, such as the Food and Drug Administration or the Environmental Protection Agency.

The first genetically engineered pet was marketed in 2003 when scientists inserted a jellyfish gene into the common zebrafish to make them glow yellow-green in the dark. "Frankenfish" was expected to be a big novelty item but sales were flat.

Many people question both the ethics and the safety of genetic engineering. Because the science is so new, there is no way of predicting potential consequences to human health and safety should a genetically engineered animal escape the lab or if genetically altered food should turn out to have unexpected consequences. Several cases of genetically altered wheat infecting normal wheat crops have been reported. The infected crops were destroyed.

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Absence of articles.

Артикль не вживається:

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smoke, smog, pollution, etc.

Particles

chalk, dirt, dust, flour, grass, hair, sand, rice, wheat, corn, etc.

beauty, confidence, courage, education, fun, happiness, health, help, honesty, hospitality, importance, intelligence, knowledge, luck, music,

Abstract nouns patience, peace, progress, politics, recreation, significance, sleep, truth, wealth, advice, slang, information, news, evidence, space, energy, grammar, behaviour, work, chaos etc.

Fields of study

chemistry, history, literature, mathematics, psychology, economics, physics, engineering, etc.

Recreation

baseball, soccer, tennis, chess, bridge, poker, athletics, travel, billiards etc.

General

driving, studying, swimming, travelling, walking, etc.

activities

Natural

weather, heat, humidity, lightning, rain, dew, fog,

phenomena

hail, snow, thunder, wind, darkness, light, sunshine, electricity, fire, etc.

clothing, equipment, furniture, garbage, jewellery, Others luggage, baggage, machinery, mail,

money/cash/change, scenery, traffic, etc.

Перед необчислюваними іменниками можна вживати слова чи словосполучення, що вказують на кількість речовини: a bottle/ jar/ cup/ jug/ glass/ can/ tin/ loaf/ piece/ bar/ kilo/ packet, etc.

Наприклад: two bottles of champagne, a glass of water, a cup of coffee, a quart of milk, a loaf of bread, a spoonful of fat, a grain of rice, a bowl of soup, a bag of flour, a piece of furniture, a piece of paper, a piece of jewellery.

Іменники, які вживаються тільки у формі множини:

The contents of his article have not been Зміст цієї статті не змінився. changed.

.

Деякі особливості вживання іменників у множині та однині.

1. Багато збірних іменників мають лише форму однини, але значення множини: police, people, cattle, etc.

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Cattle are mainly raised in the North of this country.

Велика рогата худоба в основному розводиться на півночі цієї країни. The police have arrested these thieves.

Поліція арештувала цих злодіїв.

Але такі збірні іменники як: government, staff, team, family, audience, committee, etc. можуть вживатися з дієсловом і в формі однини (залежно від контексту). Порівняйте:

The committee is ready to give its recommendations.

Комітет готовий надати свої рекомендації.

The committee are separated from the families for long periods of

time.

Члени комітету давно знаходяться окремо від своїх родин.

2.Слова, які означають назви національностей/мов, що закінчуються на – ese, -ch, -sh можуть бути в однині чи в множині – залежно від значення слова:

Chinese, French, – мови; the French – французи, the Chinese – китайці. English is spoken in many countries.

The English love tea.

3.З іменниками у формі множини, що означають суму грошей, період часу, відстань, та ін., - дієслово вживається у формі однини:

Three years is a long time to be without a job.

4.а) Деякі іменники можуть вживатися як у формі множини, так і у формі однини: fruits (різні сорти фруктів), fishes (різні види риб), people(s) (народ, нація – народи, нації):

Fruit is cheap in summer.

There are apples, plums, pears and other fruits on the table. б) Potatoes, carrots, onions, oats – на відміну від української,

вживаються у множині:

Carrots are widely grown in this region.

Морква широко вирощується в цьому регіоні. Spanish onions are sweet.

Іспанська цибуля – солодка.

Але: а carrot /potato, an onion – одна морквина, одна картоплина/цибулина.

в) Деякі необчислювані іменники (залежно від значення слова) можуть вживатися як обчислювані: hair – волосся, a hair – волосина; experience – досвід, experiences – враження; paper – папір, a paper –

газета та ін.

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Some nouns used only in plural

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NUMERALS IN CONSTRUCTIONS AND WORD-COMBINATIONS

PRONOUNS. PERSONAL AND POSSESIVE PRONOUNS

DEMONSTRATIVE PRONOUNS

1.Вказівні займенники this / these позначають щось наближене в просторі або часі, а that / those – щось віддалене.

2.Вони можуть стояти перед іменником і бути його означенням, також вживатися замість іменника: Who are these people? Give me this.

REFLEXIVE PRONOUNS

Зворотні займенники утворюються від особових або присвійних займенників та неозначеного займенникаone за допомогою суфіксів

self (в однині) та –selves (в множині)

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NOTE!

1.Дієслова behave (поводитися), feel (почуватися), afford (дозволяти собі) вживаються без зворотних займенників: I feel well – Я почуваюся добре. He behaves as usual – Він поводиться як звичайно.

2.У сучасній англійській мові дієсловаdress, wash, shave інколи вживаються без зворотних займенників.

3.Зворотні займенники з прийменникомby мають два значення – «самостійно / без допомоги» та «один /самотньо»: I’m sure I’ll do it by myself. (самостійно); Do you live by yourself? (один)

4.Help yourself / yourselves (to …) – Пригощайтесь / беріть ….

PREPOSITIONS

Прийменники місця і напряму

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