NCERT Exemplar Solutions Class 8 Science Crop Production and Management

Multiple Choice Questions:

Question 1: Which one of the following condition is not essential to grow maize?

(a) High temperature

(c) Low temperature

(b) Humidity

(d) Rainfall 

Solution 1: (c) Low temperature

In a warm and tropical climate, maize is grown. For maize production, the optimum temperature is between 180°C-270°C during the day and 140°C-150°C during the night. In order to grow maize, a cold climate is therefore not necessary.

Question 2: Propagation of ginger is generally done using

(a) Seed

(c) Root

(b) Stem (rhizome)

(d) Leaf 

Solution 2: (b) Stem (rhizome)

Ginger is an underground stem adapted to spread vegetation through its stem. There is no propagation of ginger by its root, stem or leaf.

Question 3: Which of the following statement is not true for organic manure?

(a) It enhances the water holding capacity of the soil.

(b) It has a balance of all plant nutrients.

(c) It provides humus to the soil.

(d) It improves the texture of the soil. 

Solution 3: (b) It has a balance of all plant nutrients. 

Organic manure comes from the decomposition of plants and animal waste that makes the soil rich in nutrients. But this does not mean that organic manure supplies all the nutrients in the quantity needed, so choice b) is incorrect.

Question 4: The term used for the process of separation of grains from the chaff is

(a) Sieving

(b) Threshing

(c) Winnowing

(d) handpicking 

Solution 4: (c) Winnowing 

Winnowing is a technique used for extracting the scaly, inedible chaff covering the grain to separate grains from the chaff. For this method, a machine called Combine is used. The mixture is a blend of a harvester and a thresher.

Question 5: Read the statements given below.

(i) Seeds require moisture for germination.

(ii) Plants can absorb nutrients mostly in dissolved form.

(iii) Irrigation protects crops from both frost and hot air currents.

(iv) Irrigation improves soil texture.

Choose the combination of statements which indicate the need to irrigate crops.

(a) i and ii

(b) i, ii, iii

(c) i, ii, iii, iv

(d) i and iii  

Solution 5: (a) i and ii 

When needed, irrigation supplies the crops with water and this will help the seed germinate by providing the seed with moisture. Plants in a dissolved state readily absorb nutrients along with water.

Question 6: Which of the following tools would a farmer use to remove weeds from the field?

(a) Hoe

(c) Axe

(b) Plough

(d) Cultivator  

Solution 6: (a) Hoe

The hoe is used for weed removal and soil loosening. Like a blade, Hoe works. The axe is used for the cutting of trees. The plough is used for field tilling. For ploughing, the cultivator is used.

Question 7: Which of the following is not true for fertilisers?

(a) They increase the yield.

(b) Their excessive use disturbs the balance of nutrients in the soil.

(c) They are generally used in small quantity.

(d) They are environment-friendly.  

Solution 7: (d) They are environment-friendly. 

The chemical material that is rich in basic nutrients is fertilisers. Fertilizers actually help to increase yields. However, the long-term and unnecessary use of fertilisers can reduce the fertility of soils and pollute the bodies of water.

Question 8: Given below are statements about the harmful effects of weeds on crop plants.

(i) They interfere with harvesting.

(ii) They help crop plants to grow healthily.

(iii) They compete with crop plants for water, nutrients, space and light.

(iv) They affect plant growth. Choose the correct combination of statements.

(a) i, iii, iv

(b) iii only

(c) iii, iv

(d) i, ii, iii, iv  

Solution 8: (a) i, iii, iv 

The unwanted plants that grow along with the grown crops are weeds. They compete with crops for nutrients, water and sunlight, thereby affecting the health of crops and yield.

Question 9:  The process of loosening and turning of soil is called

(a) irrigation and manuring

(c) tilling and ploughing

(b) digging and winnowing

(d) harvesting and storage 

Solution 9:  (c) tilling and ploughing 

The first steps in preparing the land for farming are tilling and ploughing. Ploughing is carried out using a plough made of either wood or iron.

Question 10:  The monsoon season in our country is during the months

(a) April to December

(b) June to September

(c) November to March

(d) January to May 

Solution 10: (b) June to September

The monsoon season in our country is during the months June to September.

Question 11:  The system of irrigation wherein water is supplied drop by drop near the roots of plants, is called

(a) pulley system

(b) drip system

(c) sprinkler system

(d) lever system 

Solution 11: (b) drip system 

The pulley device is a conventional form of irrigation where water is removed and watered from wells or other sources of water and crops. As water flows under pressure with the aid of a pump through the main pipe, it escapes from the revolving nozzles. As if it is raining, it gets sprayed on the crop. The lever system is a conventional form of irrigation where the water is separated from its source by humans or animals. This is a less effective approach for irrigation.

Very Short Answer Questions:

Question 12:  Pick out the odd one from the following words given in the box and give the reason for it.

Plough, Seed Drill, Hoe, Chain Pump, Sickle 

Solution 12:

The Seed Drill is the answer. Modern machinery used for sowing the seeds is the seed drill. Whereas in agriculture, the plough, hoe, chain pump and sickle are old and conventional tools.

Question 13: If you are given a dry piece of land for cultivation what will you do before sowing the seeds? 

Solution 13:

Crop land should be prepared for planting before sowing. The first steps in preparing the field for farming are tilling and ploughing. Ploughing is accomplished with a plough that is either made of wood or iron.

Question 14:  State whether the following statements are True or False. Correct the false statements.

(i) Using good quality seed is the only criterion to get a high yield.

(ii) Growing different crops in different seasons in the same field will deplete the soil of nutrients.

(iii) All crop plants are sown as seeds in the field.

(iv) Cells of root nodules of leguminous plants fix nitrogen.

(v) Freshly harvested grains must be dried before storing. 

Solution 14:

(i) False- Appropriate farming methods, fertiliser, and water, as well as good quality seeds, are important for good yield.

(ii) False- Growing different crops in different seasons will enhance the fertility of soil.

(iii) False - Few crops requires transplantation. Ex: Ginger

(iv) False- Rhizobium bacteria living in the root nodules of leguminous plants fix nitrogen.

(iv) True

Question 15:  During which months do farmers grow mustard in India? 

Solution 15:

Farmers in India grow mustard from October to March.

Question 16:  Which activity of the farmer can promote the growth of earthworms and microbes in the field? 

Solution 16:

Maintaining higher level of moisture in the soil by, loosening the soil can promote the growth of earthworms and microbes in the field.

Short Answer Questions:

Question 17:  Beera wants to practice crop rotation in his field. Suggest a Rabi crop and a Kharif crop which will replenish his field with nitrogen. Which crop replenishes nitrogen and why? 

Solution 17:

Kharif: Rice and Groundnut

Rabi: Mustard and Wheat 

Crops that contribute to nitrogen fixation are soyabeans, peanuts, clovers, etc.                

Question 18:  Match the agricultural implements given in Column A with their use given in Column B.

Solution 18:

Question 19:  What are organic foods?

Solution 19:

Organic food is produced without the use of any chemicals such as fertilisers, weedicides, or pesticides.

Question 20:  From the word puzzle given as Fig. 1.1 find at least eight words which are ‘farmer’s friends.’ Classify them into living and non-living.

Solution 20:

Question 21:

(a) Name the tool used with a tractor for sowing seeds in a field.

(b) What are the advantages of using this tool? 

Solution 21:

a) The seed drill is a tool that is used in combination with a tractor to sow seeds in a field.
b) Advantages of seed drill are given as under:

• Seed drill time and labour efficient.
• After sowing, the seeds are protected by dust, which protects them from the elements.
• Seeds are planted at a consistent distance and width. This prevents the seeds from being overcrowded in one spot.

Question 22:

(a) Name the practice followed for large scale rearing of farm animals.

(b) What facilities are provided to farm animals? 

Solution 22:

a) Animal Husbandry is the practice followed for large scale rearing of farm animals.
b) Shelter, food and care should be provided to animals.

Question 23:  Classify the following crops into Kharif and Rabi crops and write in the tabular column given below: Maize, paddy, mustard, pea, gram, wheat, groundnut, cotton. 

Solution 23:

Long Answer Questions:

Question 24:  Despite favourable climatic conditions, a farmer’s crop failed to give a good yield. Give the possible reasons for this. 

Solution 24:  Possible reasons for failed crop despite favourable climatic conditions are

1. No weeds are eliminated.
2. 2. His land had never been irrigated.
3. It's likely that a farmer didn't use high-quality seeds.
4. The soil was not sufficiently ploughed and tilled.
5. The farmer neglected to apply the proper fertiliser and manure.

Question 25:  As a part of the eco-club activity, students were asked to raise a kitchen garden on the school premises. They were provided with some materials given in the box. List the other materials you would require. How will you plan the garden? Write the steps. 

Solution 25:  Students will need seeds, vegetable seedlings, nursery plants, soil, manure, and water in addition to the materials provided.

Steps to raise the kitchen garden:

• In a pit, kitchen waste is stored and composted.
• The plants are planted in a suitable position to receive sunshine.
• A spade is used to dig the dirt.
• Seeds are planted with ample spacing.
• Water the plants on a daily basis.
• Compost is applied to the plant's foundation.
• Weeds are collected on a regular basis.

Question 26: Paddy is a major cereal crop in our country.

(a) In which season is paddy cultivated?

(b) Discuss the method of sowing.

(c) What measures must be taken to prevent spoilage and insect attack of harvested grains? 

Solution 26:

a) In rainy season paddy is cultivated.

b) The seeds are grown in a nursery before being transplanted into the paddy field.

c) Grain is sundried after harvesting and stored in jute bags or storage silos.

Question 27:  Unscramble the words related to crop production and its management and write in the boxes given beneath them.

Now, using the circled letters, form one word which is an activity carried out in fields, after maturation of crops. 

Solution 27:

i) SILOS
ii) THRESHING
iii) IRRIGATION
iv) RIVER

Question 28:  Given below is a conversation between two farmers Heera and Beera.

Heera: Brother Beera, your maize crops looks beautiful! They have grown pretty fast.

Beera: Yes, I have sprayed urea this time. What about you?

Heera: Well, I am still relying on good old cow dung. I am saving money on buying a tractor.

Beera: That’s good. Tractor saves a lot of time and labour.

Heera: Yes, it’s been very labour intensive for me and now these weeds have come up.

Beera: Try weedicides, they are very effective.

Now answer the following questions.

1. List the practices which are not environment-friendly and why?
2. What is the advantage of modern agriculture implements over traditional ones?
3. Name one weedicide and the precaution farmers must take during its application. 

Solution 28:

1. Using fertilisers, pesticides, weedicides, and other chemicals is not an environmentally sustainable form of agriculture because it depletes soil fertility and poses a health risk to humans.
2. Modern agricultural practises take a lot of time and effort from farmers. Modern agricultural practises demand that farming procedures be precise and effective.
3. Weedicide (2,4-D). 

Before using a weedicide, farmers should take the following precautions:

• Farmer should cover his mouth and nose.
• Don't use weed killers in abundance.