8th Science Guide Lesson 21 Crop Production and Management

8th Std Science Guide Lesson 21  Crop Production and Management | English Medium

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8th Science Guide Lesson 21 Crop Production and Management

I. Choose the best answer.

1. The process of placing seeds in the soil is called a

1. ploughing
2. sowing
3. crop production
4. crop rotation

Ans : sowing

2. The method in which water flows over the soil surface and allow it to infiltrate is

1. irrigation
2. surface irrigation
3. springler irrigation
4. drip irrigation

Ans : springler irrigation

3. Organism that control insects and pests of plant crops is

1. bio-pesticides
2. bio-fertilizers
3. earthworms
4. neem leaves

Ans : bio-pesticides

4. Effective microorganism preparation is not used in

1. seed treatment
2. foliar spray
3. soil treatment
4. bio-predators

Ans : springler irrigation

5. Which of the following is not present in Panchagavya?

1. Cow dung
2. Cow’s urine
3. Curd
4. Sugar

Ans : Sugar

II. Fill in the blanks.

1. The process of actively growing seedling from one place and planting in the main field for further growth is called __________Ans : Transplanting
2. __________ is a plant growing in a place where it is not wanted.Ans : Weed
3. The chemicals used for killing the weeds or inhibiting their growth are called as ______ Ans : Herbicide

4. __________ seeds transfers its unique characteristics to the descents.Ans : Heirloom
5. __________ centers serve as the ultimate link between ICAR and farmers. Ans : KVK (Krishi Vigyon Kendra)

6. Several popular high yielding varieties of major crops have been developed by _______ Ans : IARI (Indian Agricultural Research Institute.

III. Match the following.

1. Bio-pesticide – Neem Leaves
2. Bio-predators – Bacillus thuringiensis
3. Bio-fertilizer – Control white flies
4. Bio-indicators – Improve soil fertility
5. Bio-repellants – Quality of environment

Ans: 1 – b, 2 – c, 3 – d, 4 – e, 5 – a

IV. Answer in brief:

1. Define ploughing.

• Ploughing or tilling is the process of loosening and turning the soil up and down.
• It facilitate the availability of nutrients in the root zone of that cultivating crop.

There are two types of ploughing. They are,

1. Man ploughing
2. Machine ploughing.

2. Name the methods of sowing.

1. Sowing by hand

• This is the most economical method of sowing seed.

1. Seed Drill

• This is a modern method of sowing seeds.

1. Dibbling

• It is the placement of seed material in a furrow, pit or hole

3. What is foliar spray?

• Foliar feeding is a technique of feeding plants by applying liquid fertilizer directly to their leaves.

4. Give a brief account on Krishi Vigyan Kendra.

• Krishi Vigyan Kendra is a farm science centre. These centres serve as the ultimate link between ICAR (Indian council of Agricultural research) and farmers. Their aim is to apply agricultural research findings in practical localized settings.

5. What is bio-indicator ? How does it help human beings?

• A bio-indicator or biological indicator is any species or group of species whose function or status reveals the qualitative status of the environment
• Biological indicators are used to document and understand changes in earth’s living systems especially changes caused by the activities of an expanding human population.

6. What do you mean by weeding?

• Many other undesirable plants may grow naturally along with the main crop. These undesirable plants are called weeds. Te removal of weeds is called weeding. Weeding is an important process because weeds compete with the crop plants for the nutrients, sunlight, water, space and other resources

7. What is crop rotation?

• Crop rotation is planting a series of different crops in the same field following a defined order.

8. What is green manure?

Green undeomposed material used as manure is called green manure. It is obtined in tow metthods

• by growing green manure crops or
• by collecting green leaves from plants grown in wastelands, field bunds and forest

VIII. Answer in detail:

1. Explain the agricultural practices.

Kharif Crops:

The crops which are sown in the rainy season (i.e., from June to September) are called kharif crops. Paddy, maize, soya bean, groundnut, cotton etc., 

are kharif crops.

Rabi Crops:

The crops grown in winter season (i.e., from October to March) are called rabi crops. Examples of rabi crops are wheat, gram, pea, mustard, linseed.

Zaid Crops (Summer Crops):

The crops which are grown in summer season are called zaid crops. Muskmelon, watermelon and cucumber are examples for zaid crops.

According to utility, crops are classifed as below.

Food crops

• Paddy and maize are cultivated for human consumption.

Fodder crops

• These are useful for livestock consumption.
• g. Sorghum, millets

Fabre crops

• These crops are used for cordage and textile.
• g. Cotton, hemp

Oil crops

• Oil crops are useful in a large scale for consumption or industrial uses.
• g. Ground nut, sesame.

Ornamental crops

• These are utilized for landscape gardening.
• g- Croton, Euphorbia.

2. Give a detailed account on irrigation.

• The supply of water to crops at regular intervals is called irrigation. The time and frequency of irrigation varies from crop to crop, soil to soil and season to season. Fertilizers can also be applied through the irrigation. The various sources of irrigation are wells, tube wells, ponds, lakes, rivers, dams and canal. Effective irrigation is the controlled and uniform supply to water to crops in the required amount at the right time with the minimum expenditure.

Irrigation can be carried out by two different methods.

1. Traditional Methods
2. Modern Methods

Traditional Methods

In these methods, irrigation is done manually. Here, a farmer pulls out water from wells or canals by himself or using cattle and carries to farming fields. Pumps are also commonly used for lifting water from various sources. Diesel, biogas, electricity and solar energy are the few important sources of energy needed to run these pumps. Te method of pulling water may vary from one place to other place. Te main advantage of this method is that it is cheaper. But its efficiency is poor because of the uneven distribution of water. It also leads to heavy water loss.

1. Modern Methods

The modern irrigation methods help to overcome the problems exist in the traditional methods. It also facilitates the even distribution of moisture in the field.

The modern methods involve two systems.

• Sprinkler system
• Drip system

Sprinkler System

A sprinkler system, as its name suggests, sprinkles water over the crop and helps in an even distribution of water. This method is much advisable in areas facing water scarcity. Here a pump is connected to pipes which generate pressure and water is sprinkled through the fine nozzles of pipes.

Drip System

In drip system, water is released drop by drop exactly at the root zone using a hose or pipe. This method is considered as the effective one in regions where the availability of water is less.

3. What is weed? Explain the different methods of weed control.

In an agriculture field many other undesirable plants may grow naturally along with the main crop. These undesirable plants are called weeds. The removal of weeds is called weeding. Weeding is an important process because weeds compete with the crop plants for the nutrients, sunlight, water, space and other resources. It results in the undernourishment of crops and leads to low yield. It is mandatory to remove seeds from the field to achieve the expected yield. Farmers adopt many ways to remove weeds and control their growth. Some of them are explained below.

Mechanical methods

This is the most common method in which weeds are destroyed physically. Hand pulling or weeding with the help of weeding hole is the oldest and most efficient method for controlling weeds.

Tillage methods

It is one of the practical methods of destroying weeds of all categories. Weeds are buried in the soil and also exposed to sun heat by deep ploughing.

Crop rotation

In this method, proper rotation of crops is followed for controlling crop associated and parasitic weeds.

Summer tillage

Deep ploughing afer harvest of Rabi crop and exposing underground parts of weeds to strong sunlight during summer months is useful for destroying many annual and perennial weeds.

Biological weed control

In this method, bio agents like insects and pathogens are used to control weeds. The objectives of biological control are not eradication, but reduction and regulation of the weed population.

Chemical methods are very effective in certain cases and have great scope in weed control. The chemicals used for killing the weeds or inhibiting their growth are called herbicides. These chemicals are mixed with water and sprayed over the crops.