1. Crop Production and Management

Class 8 Science NCERT Solutions Chapter 1: Crop Production and Management (CBSE Guide with Answers & Explanations)

Chapter 1: Crop Production and Management

Extra Internal Question and Answer:

Question: What is a crop? Give an example.

Answer: When plants of the same kind are cultivated at one place on a large scale, it is called a crop. For example, a crop of wheat means that all the plants grown in a field are wheat plants.

Question: What is crop rotation? Why do farmers practice crop rotation?

Answer: Crop rotation is the practice of growing different types of crops in the same field in a fixed order over a period of time.

Farmers practice crop rotation because different crops use different nutrients from the soil. It helps in maintaining soil fertility, preventing loss of nutrients, and reducing the chances of pests and diseases.

Question: How does crop rotation help in improving soil fertility?

Answer: Crop rotation helps in improving soil fertility because different crops have different nutrient needs. Some crops, like legumes, help in fixing nitrogen in the soil. When these crops are grown in rotation with other crops, the nutrients in the soil are not fully used up and get restored naturally. This keeps the soil rich and fertile for future crops.

Question: What is a fertiliser? Why do farmers use fertilisers in fields?

Answer: A fertiliser is a substance which is rich in essential plant nutrients and is added to the soil to improve its fertility.

Farmers use fertilisers in fields because they help in supplying nutrients like nitrogen, phosphorus, and potassium to the soil. These nutrients support healthy plant growth and increase crop yield.

Question: Why is fertiliser important for plant growth?

Answer: Fertilisers are important for plant growth because they provide essential nutrients like nitrogen, phosphorus, and potassium to the soil. These nutrients help plants grow faster, become healthy, and increase crop yield.

Question: What is manure? How is manure prepared ?

Answer: Manure is a natural substance obtained by the decomposition of plant and animal waste.

Manure is prepared by dumping farm waste, animal dung, and other organic waste in pits and allowing it to decompose for a few weeks or months. During decomposition, microorganisms break down the waste and convert it into manure, which is then used to enrich the soil.

Question: Why is manure considered environment-friendly?

Answer: Manure is considered environment-friendly because it is made from natural substances like animal dung and plant waste. It does not cause pollution and helps in improving soil fertility by adding organic matter to the soil.

Question: Why is manure important for soil?

Answer: Manure is important for soil because it adds nutrients and humus to the soil. It improves the soil texture, increases its water-holding capacity, and makes the soil more fertile for better plant growth.

Question: Write the differences between fertiliser and manure.

Answer: The differences between Fertiliser and Manure is :

Fertiliser	Manure
(i) Fertiliser is a man-made inorganic salt.	(i) Manure is a natural substance obtained by the decomposition of cattle dung and plant residues.
(ii) Fertiliser is prepared in factories.	(ii) Manure can be prepared in the fields.
(iii) Fertiliser does not provide any humus to the soil.	(iii) Manure provides a lot of humus to the soil.
(iv) Fertilisers are very rich in plant nutrients like nitrogen, phosphorus and potassium.	(iv) Manure is relatively less rich in plant nutrients.

Exercises

1. Select the correct word from the following list and fill in the blanks.
float, water, crop, nutrients, preparation
(a) The same kind of plants grown and cultivated on a large scale at a place is called _____________.
(b) The first step before growing crops is _____________ of the soil.

(c) Damaged seeds would _____________ on top of water.
(d) For growing a crop, sufficient sunlight and _____________ and _____________ from the soil are essential.

Answer: (a) The same kind of plants grown and cultivated on a large scale at a place is called crop.

(b) The first step before growing crops is preparation of the soil.

(d) For growing a crop, sufficient sunlight and water and nutrients from the soil are essential.

2. Match items in column A with those in column B.
          A                                                           B
(i) Kharif crops                                (a) Food for cattle
(ii) Rabi crops                                 (b) Urea and super phosphate
(iii) Chemical fertilisers                  (c) Animal excreta, cow dung urine and plant waste
(iv) Organic manure                       (d) Wheat, gram, pea
                                                      (e) Paddy and maize

Answer: (i) Kharif crops → (e) Paddy and maize
(ii) Rabi crops → (d) Wheat, gram, pea
(iii) Chemical fertilisers → (b) Urea and super phosphate
(iv) Organic manure → (c) Animal excreta, cow dung urine and plant waste

3. Give two examples of each.
(a) Kharif crop
(b) Rabi crop

Answer: (a) Kharif crops: Paddy and Maize

(b) Rabi crops: Wheat and Gram
4. Write a paragraph in your own words on each of the following.
(a) Preparation of soil (b) Sowing
(c) Weeding (d) Threshing

Answer: (a) Preparation of soil is the first step in growing crops. The soil is ploughed and loosened so that roots can grow deep and spread easily. Loose soil has more air spaces, which helps roots to breathe properly. It also allows earthworms and microbes to grow, which improve soil fertility by adding humus.

(b) Sowing means putting seeds into the soil. Good quality, clean, and healthy seeds are chosen before sowing. Farmers prefer seeds that give high yield. Seeds are sown at proper depth and distance so that plants get enough water, nutrients, and sunlight.

(c) Weeding is the removal of unwanted plants called weeds. Weeds compete with crops for water, nutrients, light, and space. Removing weeds helps crops grow healthy and strong.

(d) Threshing is the process of separating grains from harvested crops. It is done by beating the crop or using machines like threshers.
5. Explain how fertilisers are different from manure.

Answer: Fertilisers are chemical substances made in factories and contain specific nutrients like nitrogen, phosphorus, and potassium. They act quickly and increase crop yield. Manure is a natural substance prepared from animal dung and plant waste. It improves soil structure and adds humus to the soil. Fertilisers provide nutrients fast, while manure improves soil fertility for a longer time.

6. What is irrigation? Describe two methods of irrigation which conserve water.

Answer: Irrigation is the process of supplying water to crops at regular intervals to help them grow properly.

Two methods of irrigation which conserve water are:

(i) Sprinkler system: Water is sprayed through pipes and sprinklers in the form of rain. It distributes water evenly and reduces wastage.

(ii) Drip irrigation: Water is supplied drop by drop directly to the roots of plants. This method saves maximum water and is very efficient.
7. If wheat is sown in the kharif season, what would happen? Discuss.

Answer: Wheat is a rabi crop and needs cool and dry climate to grow properly. If wheat is sown in the kharif season, it will face heavy rainfall and high temperature. Excess water can damage the crop and cause poor growth. As a result, the yield will be low or the crop may fail completely.
8. Explain how soil gets affected by the continuous plantation of crops in a field.

Answer: When crops are grown continuously in the same field, the soil loses its nutrients because plants keep using the same minerals again and again. This reduces soil fertility and affects crop yield. The structure of soil also becomes poor. To avoid this, farmers use manure, fertilisers, and practise crop rotation so that the soil remains healthy.

9. What are weeds? How can we control them?

Answer: Weeds are unwanted plants that grow along with crops in the field. They compete with crops for water, nutrients, sunlight, and space, which reduces crop yield.

Weeds can be controlled by hand weeding, using tools like hoe, and by spraying weedicides. Proper ploughing and timely removal of weeds help crops grow healthy.
10. Arrange the following boxes in proper order to make a flow chart of sugarcane crop production.

Sending crop to sugar factory

Irrigation

Harvesting

Sowing

1 2 3 4

Preparation of Soil

Ploughing the field

Manuring

5 6 7

Answer: : (5) Preparation of soil → (6) Ploughing the field → (4) Sowing → (7) Manuring → (2) Irrigation → (3) Harvesting → (1) Sending crop to sugar factory .

11. Complete the following word puzzle with the help of clues given below.

Down
1. Providing water to the crops.
2. Keeping crop grains for a long time under proper conditions.
5. Certain plants of the same kind grown on a large scale.

Across
3. A machine used for cutting the matured crop.
4. A rabi crop that is also one of the pulses.
6. A process of separating the grain from chaff.

Answer: Down : 1. Providing water to the crops: Irrigation (10 letter).

2. Keeping crop grains for a long time under proper conditions: Storage (7 letter).