TEXT C: СROPPING SYSTEM

Cropping system is a method of growing crops and producing high yields without weakening the soil. It involves the combination of different production techniques to provide for the best possible use of the land. In determining the crops and production methods best suited for their land, farmers must consider the composition of their soil; the slope, drainage, and erosion problems of their land; and the land's past cropping history. Such production techniques as different cultivation methods, rotation of crops, and the proper use of fertilizers and pesticides are used in different combinations to aid the farmer.

One of the oldest and most widely used ways of preserving the soil is through the rotation of crops (alternating the crops grown in a field from one year to the next). A single crop will use up vital minerals and organic matter in the soil if it is grown in the same field year after year. But different kinds of crops planted in the field on a regular schedule will replace lost minerals and organic matter and help break up plant disease and insect cycles. For example, corn takes nitrogen out of the soil, but such crops as alfalfa and clover put nitrogen into the soil. If corn is planted in a field one year, alfalfa or clover may be planted the next year to replace the nitrogen used by the corn crop. The nitrogen-producing crop can also be ploughed into the soil. When it rots, it replaces lost organic matter and enriches the soil. On sloping land, grasses and deep-rooted crops are often alternated with other crops to hold the soil in place and prevent erosion. Crop rotation can also improve soil structure and fertility by alternating deep-rooted and shallow-rooted plants.

The use of fertilizers (substances that are added to soil to help plants grow) is gradually replacing the crop rotation system as a means of producing the most profitable crops year after year while still keeping soil fertile. Farmers use various kinds of fertilizers to help produce abundant crops.

Nitrogen fertilizers and other fertilizers can restore lost minerals to soil. When these fertilizers are added, and the proper cultivation and pest control methods are used, the same crop can be planted year after year without harming the soil.

Other developments that aid the farmer include chemical pesticides that kill harmful insects, weeds, and micro-organisms.

The Environmental Protection Agency (EPA or USEPA) defines a pesticide as "any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest ".

A pesticide may be a chemical substance or biological agent (such as a virus or bacteria) used against pests including insects, plant pathogens, weeds, molluscs, birds, mammals, fish, nematodes (roundworms) and microbes that compete with humans for food, destroy property and spread diseases. Pesticides are usually, but not always, poisonous to humans.

Pest control is a term that identifies various methods used to reduce or eliminate pests. Any living thing that kills plants or stunts their growth, carries disease, or is harmful in other ways may be considered a pest. Pests include insects, weeds, mammals, pathogens (disease-causing micro-organisms), and nematodes (microscopic roundworms). The two major pest control methods are (1) pesticides, chemicals used to kill pests, and (2) natural pest control, which uses various preventive measures instead of chemicals. Many pest control experts favour a diverse approach called integrated pest management, which combines pesticides and natural control methods.

Pesticides are classified according to the pests they control. The four main types of pesticides are (1) herbicides, (2) fungicides, (3) rodenticides, and (4) insecticides.

Herbicides eliminate plants that grow where they are not wanted. Farmers use them to reduce weeds among their crops. Herbicides also control weeds in such public areas as parks and ponds. People use herbicides in their yards to get rid of crab grass, dandelions, and other weeds.

Fungicides. Certain fungi cause disease and may infect both plants and animals, including human beings. Fungicides control plant diseases that infect food crops. Wood used for building houses is often treated with fungicides to prevent dry rot.

Rodenticides are used to control rats and other rodents that destroy stored food. Rats also carry bacteria that cause such diseases as rabies and typhus.

Insecticides. Farmers use insecticides to protect their crops from insect damage. In urban areas, public health officials use them to fight mosquitoes and other insects that carry germs. People use insecticides indoors to control such pests as ants and cockroaches.

Effects of pesticide use. Pests may develop resistance to pesticides so that higher dosages need to be used over time. Eventually pesticides can become ineffective, so there is a constant need to create new pesticides. More than 600 species of plant and animal pests have been found to be resistant to at least one type of pesticide.

Pesticides are poisons that can have unintended effects on people and on the environment. Wind or rain can carry herbicides from weeds to desirable plant species, such as trees and flowers. Insecticides kill beneficial insects, such as honey bees and ladybugs.

People used chemical pesticides for many years without realizing their harmful effects on humans and the environment. In 1962, American marine biologist Rachel Carson wrote the book Silent Spring to call public attention to pesticide dangers. The book helped to reduce pesticide use throughout the world.

Natural pest control helps avoid pest attacks without the use of chemical pesticides. Pest managers often use biological control methods, such as encouraging a pest's natural enemies.

Integrated pest management, also known as IPM, has largely replaced reliance on pesticides as an approach to pest control. IPM combines a limited use of chemical pesticides with natural control methods. Pest managers track levels of pest infestation and apply pesticides only when they will produce the greatest benefits. They use natural control measures until the cost of not controlling a pest exceeds the cost of applying a pesticide.

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• From World Book"Pest control" by Mike Linker, Ph.D., Integrated Pest Management Coordinator, Department of Crop Science and Entomology, North Carolina State University.

1. Підберіть протилежні за значенням вирази:

2. Підберіть визначення до наступних термінів:

3. Доповніть речення артиклями та прийменниками, користуючись текстом:

1. Cropping system is … method … growing crops and producing high yields … weakening … soil.

2. It involves … combination … different production techniques to provide … … best possible use … the land.

3. One of …oldest and most widely used ways … preserving … soil is … the rotation of crops.

4. … single crop will use up vital minerals and organic matter in … soil if it is grown … … same field year …year.

5. … nitrogen-producing crop can also be ploughed … … soil.

6. … use … fertilizersis gradually replacing … crop rotation system as … means … producing … most profitable crops year … year while still keeping soil fertile.

4. Дайте відповіді на запитання:

1. What is a cropping system method concerned with?

2. What must farmers consider before growing crops?

3. What the main cultivation methods do you know?

4. What is the oldest and most widely used way of preserving the soil?

5. Can crop rotation improve soil fertility by alternating deep-rooted and shallow-rooted plants?

6. Is a pesticide a chemical substance or biological agent?

7. Are pesticides very poisonous to humans?

8. What are two main pest control methods?

9. What four main types of pesticides do you know?

10. Which of them reduces weeds?

11. Which kind of pesticides controls fungi diseases?

12. What natural pest control methods do farmers often use?

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